JP2011222599A - Semiconductor light-emitting element, manufacturing method of semiconductor light-emitting element, lamp, electronic equipment and mechanical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light-emitting element that can be driven with low voltage and has a high light extraction efficiency, and to provide a lamp, electronic equipment and a mechanical device equipped with the light-emitting element.SOLUTION: In a semiconductor light-emitting element 1, an n-type semiconductor layer 12, a light-emitting layer 13, a p-type semiconductor layer 14, and a titanium oxide-based conductive film layer 15 having Anatase-type crystal structures are laminated on one surface 11a of a substrate 11 in the mentioned order. An oxide layer containing Zr element with a concentration range of 5 mg/cmto 5 g/cmexists between the p-type semiconductor layer 14 and the titanium oxide-based conductive film layer 15.

Description

  The present invention relates to a semiconductor light-emitting device, a method for manufacturing a semiconductor light-emitting device, a lamp, an electronic device, and a mechanical device, and in particular, includes a titanium oxide-based conductive film layer and can be driven at a low voltage and has excellent light extraction efficiency. The present invention relates to a semiconductor light emitting device that can be obtained.

  In recent years, GaN-based compound semiconductors have attracted attention as semiconductor materials for short wavelength optical semiconductor light emitting devices. As a semiconductor light-emitting device using a GaN-based compound semiconductor, an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer made of a GaN-based compound semiconductor are stacked in this order on a sapphire single crystal substrate. In which the positive electrode is formed and the negative electrode is formed on the n-type semiconductor layer.

In general, external quantum efficiency is used as an index indicating the output of a semiconductor light emitting device. The external quantum efficiency is a product of the internal quantum efficiency and the light extraction efficiency.
As a method for improving the light extraction efficiency, materials having different refractive indexes constituting a semiconductor light emitting element such as an interface between a GaN-based compound semiconductor layer and an electrode constituting an n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer may be used. There is a method of reducing the reflection loss of light generated at the interface.

  As a method for reducing the reflection loss of light and improving the light extraction efficiency, there is a method in which fine unevenness processing is performed on the light extraction surface side. For example, in Patent Document 1, a GaN-based compound semiconductor layer serving as a semiconductor light-emitting element is grown on an off-substrate on the sapphire substrate C-plane (0001), and the uppermost surface of the GaN-based compound semiconductor layer is a non-mirror surface. A gallium nitride compound semiconductor light emitting device is disclosed. By performing fine uneven processing on the light extraction surface side of the GaN-based compound semiconductor layer to make it a non-mirror surface, it is possible to reduce reflection loss of light generated at the interface between materials having different refractive indexes.

  However, in the technique described in Patent Document 1, since the GaN compound semiconductor layer is subjected to fine unevenness processing, the GaN compound semiconductor remains damaged, and the internal quantum efficiency that determines the output of the semiconductor light emitting device is reduced. Therefore, a sufficient output of the semiconductor light emitting device could not be obtained.

Another method for improving the light extraction efficiency is a method for reducing light absorption by an electrode or a protective film formed on the light extraction surface. Examples of a method for reducing light absorption by the electrode formed on the light extraction surface and the protective film include a method of providing a transparent electrode on the p-type semiconductor of the GaN-based compound semiconductor light emitting device.
Examples of the transparent electrode provided on the p-type semiconductor include a light-transmitting conductive film such as ITO. However, the refractive index 1.9 of ITO is smaller than the refractive index 2.6 of GaN compound semiconductor, and the difference in refractive index between ITO and GaN compound semiconductor is large. Total reflection occurred between them, and the light could not be extracted sufficiently.

  As a technique for solving this problem, a technique has been proposed in which a transparent electrode made of a titanium oxide-based conductive film is provided on the p-type semiconductor layer instead of ITO. The refractive index of titanium oxide is 2.6 with respect to light having a wavelength of 450 nm, which is almost the same value as the refractive index of a GaN-based compound semiconductor. Titanium oxide is an insulator, but it has been clarified that it can be made into a conductor by adding Nb or the like to titanium oxide (see Non-Patent Document 1).

Patent Document 2 discloses a light-emitting element in which an n-type semiconductor layer, a light-emitting layer, a p-type semiconductor layer, and a titanium oxide-based conductive film layer are stacked in this order. There is disclosed a light emitting device having a first layer as a layer and a second layer as a current diffusion layer disposed on the p-type semiconductor layer side of the first layer.
Patent Document 3 discloses a semiconductor light-emitting element in which an n-type semiconductor layer, a light-emitting layer, a p-type semiconductor layer, and a titanium oxide-based conductive layer are stacked in this order, and at least one of the titanium oxide-based conductive layers. A semiconductor light-emitting device having a concavo-convex surface formed on the part is disclosed.

Japanese Patent No. 2836687 JP 2007-220971 A JP 2007-220972 A

American Institute of Physics “A Transparent Metal: Nb-Doped Anatase TiO2”, Applied Physic P 252101 (2005)}, (United States), June 20, 2005, p252101-252103.

  However, in the techniques described in Patent Document 2 and Patent Document 3, since the resistivity of the titanium oxide conductive film layer is high, the sheet resistance is increased. As a result, current cannot be diffused, and the drive voltage of the semiconductor light emitting element cannot be sufficiently reduced. As a method of reducing the sheet resistance of the titanium oxide-based conductive film layer, a method of increasing the thickness of the titanium oxide-based conductive film layer can be considered. However, when the thickness of the titanium oxide-based conductive film layer is increased, there is a disadvantage in that the transmittance decreases and the light extraction efficiency decreases.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a semiconductor light-emitting element that can be driven at a low voltage and has an excellent light extraction efficiency, a lamp, an electronic device, and a mechanical device including the semiconductor light-emitting element. To do.
It is another object of the present invention to provide a method for manufacturing a semiconductor light emitting device that can be driven at a low voltage and has excellent light extraction efficiency.

In order to solve the above-mentioned problems, the present inventor has intensively studied paying attention to the crystal structure of the titanium oxide-based conductive film layer. As a result, when the crystal structure of the titanium oxide-based conductive film layer is composed only of anatase type, the present inventor has good conductivity even if the thickness is reduced so that sufficient transmittance can be obtained. The knowledge that it becomes the titanium oxide type electrically conductive film layer with a low resistivity obtained was acquired.
In addition, the present inventor conducted further earnest studies and formed a titanium oxide-based film on the zirconium oxide layer using an oxide layer (hereinafter also referred to as a zirconium oxide layer) in which a Zr element is present as a base layer. , A titanium oxide film having a crystal structure of anatase type and amorphous type can be formed, and a titanium oxide film having a crystal structure of only anatase type can be formed by annealing the obtained titanium oxide film. Obtained knowledge.
That is, the present inventor uses the oxide layer in which the Zr element is present as the base layer, so that the crystal structure of the titanium oxide film formed on the oxide layer is likely to be anatase type. The present inventors have obtained the knowledge that even if there is, it can be transferred to the anatase type by further annealing treatment.

  And this inventor repeated examination further based on the above-mentioned knowledge, and forms a sufficiently thin zirconium oxide layer on the p-type semiconductor layer that does not hinder the resistivity and light extraction efficiency of the electrode layer, By forming a titanium oxide-based conductive film layer containing anatase type crystal structure on the zirconium oxide layer, an electrode layer with low resistivity and excellent light extraction efficiency can be formed on the p-type semiconductor layer, The present invention has been completed by finding that a semiconductor light emitting device that can be driven at a low voltage and has an excellent light extraction efficiency can be realized. That is, the present invention relates to the following.

(1) An n-type semiconductor layer, a light emitting layer, a p-type semiconductor layer, and a titanium oxide-based conductive film layer containing an anatase crystal are laminated in this order on one surface of the substrate, and the p-type semiconductor layer the semiconductor light emitting element, wherein said between the titanium oxide based conductive film layer, the oxide layer containing Zr element in a concentration range of 5mg ^/ cm ³ ~5g / cm 3 is present with.

(2) The semiconductor light-emitting element according to item 1 above, wherein the oxide layer containing the Zr element has a thickness of 5 nm or less.
(3) The above item 1 or item 2, wherein the titanium oxide based conductive film layer contains at least one element selected from the group consisting of Ta, Nb, V, Mo, W, and Sb. Semiconductor light emitting device.

(4) The titanium oxide-based conductive film layer is made of Ti _(1-X) Nb _x O ₂ (where X = 0.03 to 0.09), or 1 or 2 above The semiconductor light-emitting device described in 1.
(5) The semiconductor light-emitting element according to any one of the preceding items 1 to 4, wherein the n-type semiconductor layer, the light-emitting layer, and the p-type semiconductor layer are made of a GaN-based compound semiconductor.
(6) A protective film containing any of Nb ₂ O ₅ , Ta ₂ O ₅ , TiO ₂ , and ZrO ₂ is provided on the titanium oxide-based conductive film layer. The semiconductor light-emitting device according to any one of the above.
(7) The semiconductor light-emitting element according to item 6 above, wherein unevenness is formed on at least a part of the surface of the protective film.

(8) After laminating an n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer in this order on one surface of the substrate, a Zr element of 5 mg / cm ³ to 5 g is formed on the p-type semiconductor layer by sputtering. A step of forming an oxide layer containing a Zr element under conditions existing at a concentration in the range of / cm ³ , a step of forming a titanium oxide-based film by sputtering on the oxide layer containing the Zr element, And a step of forming a titanium oxide-based conductive film layer by annealing the titanium oxide-based film in a range of 300 to 500 ° C.
(9) In the step of forming the titanium oxide-based film, the titanium oxide-based film having a crystal structure of anatase type and amorphous type is formed, and then the titanium oxide-based film is annealed, whereby the crystal structure is 9. The method for producing a semiconductor light-emitting element according to 8 above, wherein a titanium oxide-based conductive film layer made only of anatase type is formed.

(10) A lamp comprising the semiconductor light emitting device according to any one of (1) to (7).
(11) An electronic device in which the lamp according to (10) is incorporated.
(12) A mechanical apparatus in which the electronic device according to (11) is incorporated.

The semiconductor light-emitting device of the present invention, oxide containing a p-type semiconductor layer, between the crystal structure consisting of anatase titanium oxide based conductive film layer, the Zr element in a concentration range of 5mg ^/ cm ³ ~5g / cm 3 Since the physical layer is present, it can be driven at a low voltage and has excellent light extraction efficiency.
More specifically, the semiconductor light-emitting device of the present invention has a thickness of an oxide layer containing a Zr element containing a Zr element in a concentration range of 5 mg / cm ^{3 to} 5 g / cm ^3. Is 5 nm or less, it does not hinder the resistivity and light extraction efficiency of the electrode layer including the titanium oxide-based conductive film layer, and sufficient conductivity is achieved by the titanium oxide-based conductive film layer whose crystal structure includes anatase type. Sex is obtained. As a result, the semiconductor light emitting device of the present invention can be driven at a low voltage and has excellent light extraction efficiency.

In the method for manufacturing a semiconductor light emitting device of the present invention, an n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer are stacked in this order on one surface of a substrate, and then sputtered on the p-type semiconductor layer. A step of forming an oxide layer (zirconium oxide layer) containing Zr element under the condition that the Zr element is present in a concentration range of 5 mg / cm ³ to 5 g / cm ³ , and oxidation by sputtering on the zirconium oxide layer. Since it is a method comprising a step of forming a titanium-based film and a step of forming a titanium oxide-based conductive film layer by annealing the titanium oxide-based film in the range of 300 to 500 ° C., driving at a low voltage And a semiconductor light emitting device having excellent light extraction efficiency can be obtained.

In the method for manufacturing a semiconductor light emitting device of the present invention, a titanium oxide film having a crystal structure of anatase type and amorphous type was obtained in the step of forming the titanium oxide film on the zirconium oxide layer by sputtering. Even if it is a case, the titanium oxide type electrically conductive film layer which a crystal structure has only a structure of an anatase type is obtained by annealing the said titanium oxide type film. As a result, a titanium oxide-based conductive film layer having a low resistivity can be obtained.
In other words, when the Zr element is present in the zirconium oxide layer formed on the p-type semiconductor layer at a concentration in the range of 5 mg / cm ³ to 5 g / cm ³ , annealing is performed on the zirconium oxide layer. The crystal structure of the titanium oxide-based film can be made anatase, and a titanium oxide-based conductive film layer having a low resistivity can be obtained.

Moreover, the zirconium oxide layer formed in the manufacturing method of the semiconductor light-emitting device of this invention is arrange | positioned between a p-type semiconductor layer and a titanium oxide type film | membrane, Zr element is 5 mg / cm < ³ > -5g / It is included in the range of cm ³ . If the Zr element contained in the zirconium oxide layer is less than 5 mg / cm ^3, it may not function sufficiently as an underlayer for forming the titanium oxide-based conductive film layer. When the content of the Zr element contained in the zirconium oxide layer is within the above range, a titanium oxide-based conductive film having a crystal structure consisting only of anatase type is obtained after the annealing treatment.

  Thus, according to the method for manufacturing a semiconductor light emitting device of the present invention, a zirconium oxide layer that does not hinder the resistivity and light extraction efficiency of the electrode layer on the p-type semiconductor layer, and the low resistivity oxidation. A semiconductor light emitting device having an electrode layer including a titanium-based conductive film layer is obtained. That is, according to the method for manufacturing a semiconductor light emitting device of the present invention, an electrode layer having a low resistivity and excellent light extraction efficiency is formed, and a semiconductor light emitting device that can be driven at a low voltage and has excellent light extraction efficiency is obtained. It is done.

  Further, in the method for manufacturing a semiconductor light emitting device of the present invention, since the zirconium oxide layer and the titanium oxide film are formed by sputtering, compared with the case where the zirconium oxide layer and the titanium oxide film are formed by different methods, Can be manufactured efficiently.

  Further, since the lamp, the electronic device, and the mechanical device of the present invention include the semiconductor light emitting element of the present invention, the lamp, the electronic device, and the mechanical apparatus can be driven at a low voltage and have an excellent semiconductor light emitting element having excellent light extraction efficiency. Become.

It is the top view which showed an example of the semiconductor light-emitting device of this invention. It is sectional drawing in the A-A 'line | wire of the semiconductor light-emitting device shown in FIG. FIG. 3 is a manufacturing process diagram for explaining an example of a method for manufacturing the semiconductor light emitting element shown in FIGS. 1 and 2. FIG. 3 is a manufacturing process diagram for explaining an example of a method for manufacturing the semiconductor light emitting element shown in FIGS. 1 and 2. FIG. 3 is a manufacturing process diagram for explaining an example of a method for manufacturing the semiconductor light emitting device shown in FIGS. FIG. 3 is a manufacturing process diagram for explaining an example of a method for manufacturing the semiconductor light emitting element shown in FIGS. 1 and 2. FIG. 3 is a manufacturing process diagram for explaining an example of a method for manufacturing the semiconductor light emitting device shown in FIGS. It is the cross-sectional schematic diagram which showed an example of the lamp | ramp of this invention.

Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the drawings used in the following description may show the characteristic portions for explaining the present invention in an enlarged manner, and the dimensional ratios of the respective constituent elements are not always the same as the actual ones.
"Semiconductor light emitting device"
1 is a plan view showing an example of the semiconductor light emitting device of the present invention, and FIG. 2 is a cross-sectional view taken along the line AA ′ of the semiconductor light emitting device shown in FIG. A semiconductor light emitting device 1 shown in FIGS. 1 and 2 includes an n-type semiconductor layer 12, a light-emitting layer 13, a p-type semiconductor layer 14, on one surface 11a (upper surface in FIG. 2) of a substantially rectangular substrate 11. The electrode layer 19 is laminated in this order.

In the semiconductor light emitting device 1 shown in FIGS. 1 and 2, the electrode layer 19 includes a zirconium oxide layer 39 and a titanium oxide-based conductive film layer 15 formed on the zirconium oxide layer 39.
Further, the semiconductor light emitting element 1 shown in FIGS. 1 and 2 is a face-up type semiconductor light emitting element 1. A circular positive electrode 17 is formed on the electrode layer 19 of the semiconductor light emitting element 1. Further, in the semiconductor light emitting device 1, the light emitting layer 13, the p-type semiconductor layer 14, and the n-type semiconductor layer 12 are partially cut out to expose a part of the n-type semiconductor layer 12, and the n-type semiconductor layer 12 is exposed. A circular negative electrode 18 is formed on the exposed surface 12a.

As shown in FIGS. 1 and 2, the side surface 17 b and upper surface peripheral portion 17 a of the positive electrode 17, the side surface 15 b and one surface 15 a of the titanium oxide based conductive film 15, the side surface 39 b of the zirconium oxide layer 39, and the light emitting layer 13. And the side surface of the p-type semiconductor layer 14, a part of the side surface of the n-type semiconductor layer 12, the exposed surface 12a of the n-type semiconductor layer 12, the side surface of the negative electrode 18 and the periphery of the upper surface are continuously covered. A protective film 16 is formed.
The protective film 16 is preferably provided in order to suppress the deterioration of the semiconductor light emitting element 1, but the protective film 16 may not be provided.

<Board>
As the substrate 11, sapphire single crystal (Al ₂ O ₃ ; A plane, C plane, M plane, R plane), spinel single crystal (MgAl ₂ O ₄ ), ZnO single crystal, LiAlO ₂ single crystal, LiGaO ₂ single crystal. Known substrate materials such as oxide single crystal such as MgO single crystal, Si single crystal, SiC single crystal, GaAs single crystal, AlN single crystal, GaN single crystal and boride single crystal such as ZrB ₂ are used without any limitation. be able to. Among these substrate materials, it is particularly preferable to use a sapphire single crystal and a SiC single crystal as the substrate 11. The plane orientation of the substrate is not particularly limited. Moreover, a just board | substrate may be sufficient and the board | substrate which provided the off angle may be sufficient.

<Nitride compound semiconductor>
As shown in FIG. 2, an n-type semiconductor layer 12, a light emitting layer 13, and a p-type semiconductor layer 14 are stacked on the substrate 11.
The n-type semiconductor layer 12, the light emitting layer 13, and the p-type semiconductor layer 14 are preferably made of a GaN-based compound semiconductor. The refractive index of the GaN compound semiconductor is 2.6. As the GaN-based compound semiconductor, for example, the general formula _{Al X Ga Y In Z N 1} -A M A ( and in 0 ≦ X ≦ 1,0 ≦ Y ≦ 1,0 ≦ Z ≦ 1, X + Y + Z = 1. Symbol M Represents a Group V element different from nitrogen (N), and 0 ≦ A <1).

  The GaN-based compound semiconductor may contain other group III elements in addition to Al, Ga, and In.

<N-type semiconductor layer>
The n-type semiconductor layer 12 is preferably composed of an underlayer, an n-type contact layer, and an n-type cladding layer. The n-type contact layer may also serve as the base layer and / or the n-type cladding layer.
_Underlayer, Al _{X Ga 1-X} N layer (0 ≦ x ≦ 1, preferably 0 ≦ x ≦ 0.5, and more preferably 0 ≦ x ≦ 0.1) preferably being composed. The film thickness of the underlayer is preferably 0.1 μm or more, more preferably 0.5 μm or more, and most preferably 1 μm or more. By setting the thickness of the underlayer to 1 μm or more, an Al _X Ga _1-X N layer having good crystallinity can be easily obtained.

The underlayer is preferably undoped (<1 × 10 ¹⁷ / cm ³ ). When the underlayer is undoped, good crystallinity can be maintained. In addition, when the n-type impurity is doped in the base layer, it is preferably in the range of 1 × 10 ¹⁷ to 1 × 10 ¹⁹ / cm ³ . Although it does not specifically limit as an n-type impurity doped by a base layer, For example, Si, Ge, Sn, etc. can be mentioned, Si and Ge are preferable.

The n-type contact layer is composed of an Al _X Ga _1-X N layer (0 ≦ x ≦ 1, preferably 0 ≦ x ≦ 0.5, more preferably 0 ≦ x ≦ 0.1), similarly to the base layer. It is preferable that The n-type contact layer is preferably doped with n-type impurities. The concentration of the n-type impurity in the n-type contact layer is preferably 1 × 10 ¹⁷ to 1 × 10 ¹⁹ / cm ³ , and more preferably 1 × 10 ¹⁸ to 1 × 10 ¹⁹ / cm ³ . When the concentration of the n-type impurity in the n-type contact layer is 1 × 10 ¹⁷ to 1 × 10 ¹⁹ / cm ^3, it is possible to maintain good ohmic contact with the negative electrode, suppress the generation of cracks, and provide good crystallinity. Can be maintained. Although it does not specifically limit as an n-type impurity of an n-type contact layer, For example, Si, Ge, Sn, etc. can be mentioned, Si and Ge are preferable.

  The n-type contact layer and the underlayer are preferably made of a GaN compound semiconductor having the same composition. The total film thickness of the n-type contact layer and the underlayer is preferably 1 to 20 μm, more preferably 2 to 15 μm, and further preferably 3 to 12 μm. When the total film thickness of the n-type contact layer and the underlayer is 1 to 20 μm, the crystallinity of the GaN-based compound semiconductor can be maintained better.

  An n-type cladding layer is preferably provided between the n-type contact layer and the light emitting layer 13. When the n-type cladding layer is provided, it is possible to fill a portion of the outermost surface of the n-type contact layer that has deteriorated flatness. The n-type cladding layer can be formed of AlGaN, GaN, GaInN, or the like. In the specification, the composition ratio of each element may be omitted and described as AlGaN, GaN, or GaInN. The n-type cladding layer may have a superlattice structure in which two or more compositions selected from these compositions are stacked a plurality of times. The band gap of the n-type cladding layer is larger than the band gap of the light emitting layer 13.

The film thickness of the n-type cladding layer is not particularly limited, but is preferably 0.005 to 0.5 μm, and more preferably 0.005 to 0.1 μm. The n-type cladding layer has an n-type doping concentration of preferably 1 × 10 ¹⁷ to 1 × 10 ²⁰ / cm ³ , and more preferably 1 × 10 ¹⁸ to 1 × 10 ¹⁹ / cm ³ . When the n-type doping concentration of the n-type cladding layer is 1 × 10 ¹⁷ to 1 × 10 ²⁰ / cm ³ , good crystallinity can be maintained and the operating voltage of the semiconductor light emitting device 1 can be reduced.

<Light emitting layer>
Examples of the GaN-based compound semiconductor used for the light emitting layer 13 include Ga _1-s In _s N (0 <s <0.4).

The light emitting layer 13 may have a single quantum well (SQW) structure or a multiple quantum well (MQW) structure. As a multiple quantum well (MQW) structure, for example, a well layer made of Ga _1-s In _s N (hereinafter referred to as GaInN well layer) and Al _c Ga _1-c N (0 having a larger band gap energy than this well layer) And a plurality of barrier layers (hereinafter referred to as Al _c Ga _1-c N barrier layers) made of ≦ c <0.3. The well layer and / or the barrier layer constituting the multiple quantum well (MQW) structure may be doped with impurities. Specifically, a Si-doped GaN barrier layer may be used as a barrier layer constituting a multiple quantum well (MQW) structure.

<P-type semiconductor layer>
The p-type semiconductor layer 14 is preferably composed of a p-cladding layer and a p-contact layer, but the p-contact layer may also serve as the p-cladding layer.
The p-cladding layer has a composition larger than the band gap energy of the light-emitting layer 13 and is not particularly limited as long as it can confine carriers in the light-emitting layer 13. For example, the p-cladding layer may be made of Al _d Ga _1-d N (0 <d ≦ 0.4, preferably 0.1 ≦ d ≦ 0.3). The thickness of the p-cladding layer is not particularly limited, but is preferably 1 to 400 nm, and more preferably 5 to 100 nm. The p-type doping concentration of the p-clad layer is preferably 1 × 10 ¹⁸ to 1 × 10 ²¹ / cm ³ , and more preferably 1 × 10 ¹⁹ to 1 × 10 ²⁰ / cm ³ . By setting the p-type doping concentration of the p-cladding layer to 1 × 10 ¹⁸ to 1 × 10 ²¹ / cm ³ , a good p-type crystal can be obtained without reducing the crystallinity.

As the p contact layer, a GaN-based compound semiconductor containing Al _e Ga _1-e N (0 ≦ e <0.5, preferably 0 ≦ e ≦ 0.2, more preferably 0 ≦ e ≦ 0.1) is used. It is preferable to use it. By making the Al composition in Al _e Ga _1-e N 0 ≦ e <0.5, it is possible to maintain good crystallinity and to make good ohmic contact with the p ohmic electrode. It is preferable that the concentration of the p-type dopant of the p-contact layer is ^{1 × 10 18 ~1 × 10 21} / cm 3, more preferably ^{5 × 10 19 ~5 × 10 20} / cm 3. By setting the concentration of the p-type dopant in the p-contact layer to 1 × 10 ¹⁸ to 1 × 10 ²¹ / cm ³ , it is possible to maintain good ohmic contact, prevent occurrence of cracks, and maintain good crystallinity. . Although it does not specifically limit as a p-type dopant (p-type impurity) of a p contact layer, For example, Mg is mentioned. The thickness of the p-contact layer is not particularly limited, but is preferably 0.01 to 0.5 μm, and more preferably 0.05 to 0.2 μm. The light emission output can be improved by setting the thickness of the p contact layer to 0.01 to 0.5 μm.

<Electrode layer>
As shown in FIGS. 1 and 2, the electrode layer 19 is preferably formed so as to cover almost the entire surface of the p-type semiconductor layer 14 in order to diffuse the current over a wide range on the p-type semiconductor layer 14. However, it may be formed in a lattice shape or a tree shape with a gap. The electrode layer 19 is formed of a zirconium oxide layer 39 and a titanium oxide-based conductive film layer 15.
In the present embodiment, the example having the zirconium oxide layer 39 has been described as an example. However, between the p-type semiconductor layer 14 and the titanium oxide-based conductive film layer 15, 5 mg / cm ^{3 to} 5 g / cm. It is sufficient that an oxide layer containing a Zr element having a concentration range of ³ exists, and the zirconium oxide layer 39 may not exist stoichiometrically. Specifically, for example, the zirconium oxide constituting the zirconium oxide layer 39 diffuses into the titanium oxide conductive film layer 15 and the p-type semiconductor layer 14 in the manufacturing process after the zirconium oxide layer 39 is formed, thereby oxidizing the zirconium oxide layer 39. even a case where the zirconium layer 39 is not present stoichiometrically, p-type between the semiconductor layer 14 and titanium oxide-based conductive layer 15, Zr element in the concentration range of ^5mg / cm ^{3 ~5g} / cm 3 It is sufficient that an oxide layer containing is present.

When the zirconium oxide layer 39 is made of zirconium oxide crystals having a stoichiometric composition, the density is 5 g / cm ^{3 due} to its specific gravity (6.5 g / cm ³ ). Therefore, when the Zr element is present as an oxide having a concentration of 5 g / cm ³ , it can be considered that a zirconium oxide crystal having a stoichiometric composition is formed.

Thus, the zirconium oxide layer 39 exists between the p-type semiconductor layer 14 and the titanium oxide-based conductive film layer 15, and the Zr element is in the range of 5 mg / cm ³ to 5 g / cm ³ . It is included. If the Zr element contained in the zirconium oxide layer 39 is less than 5 mg / cm ^3, it may not function sufficiently as a base layer when the titanium oxide conductive film layer 15 is formed in the manufacturing process of the semiconductor light emitting device. That is, if the content of the Zr element contained in the zirconium oxide layer 39 is small, the titanium oxide conductive film layer 15 in which the crystal structure of the titanium oxide conductive film layer 15 is only anatase type cannot be obtained after the annealing treatment. On the other hand, when the content of the Zr element contained in the zirconium oxide layer 39 exceeds 5 g / cm ³ , the conductivity between the p-type semiconductor layer 14 and the titanium oxide-based conductive film layer 15 becomes insufficient, and the semiconductor light emitting device 1 drive voltage Vf cannot be made sufficiently low. Accordingly, Zr element contained in the zirconium oxide layer 39 is in the range of ^{50mg / cm 3 ~5g / cm 3} , preferably in the range of ^{0.5g / cm 3 ~4g / cm 3} .

  The thickness of the zirconium oxide layer 39 is preferably 5 nm or less. When the film thickness of the zirconium oxide layer 39 is 5 nm or less, the Zr element is interposed between the p-type semiconductor layer 14 and the titanium oxide-based conductive film layer 15 in a region having a film thickness of 5 nm or less. . When the film thickness of the zirconium oxide layer 39 is 5 nm or less, the conductivity between the p-type semiconductor layer 14 and the titanium oxide conductive film layer 15 is good, and the drive voltage Vf of the semiconductor light emitting element 1 can be reduced. . The film thickness of the zirconium oxide layer 39 is preferably 0.3 nm or more. When the thickness of the zirconium oxide layer 39 is less than 0.3 nm, the thickness of the zirconium oxide layer 39 is too thin, and the function as a base layer when forming the titanium oxide conductive film layer 15 by the zirconium oxide layer 39 is achieved. It becomes difficult to obtain a titanium oxide conductive film 15 having a crystal structure consisting only of anatase type.

<Titanium oxide conductive film layer>
The titanium oxide based conductive film 15 is formed on the zirconium oxide layer 39 and functions as a transparent electrode for diffusing current. The crystal structure of the titanium oxide based conductive film 15 is composed only of the anatase type. In the present embodiment, since the crystal structure of the titanium oxide-based conductive film layer 15 is composed only of anatase type, it has good conductivity. Therefore, the titanium oxide-based conductive film layer 15 has a low sheet resistance even if it is thinned so that a sufficiently high transmittance can be obtained.

The titanium oxide-based conductive film layer 15 has a photocatalytic action for decomposing water and organic substances. Since the crystal structure of the titanium oxide-based conductive film 15 of the present embodiment is composed only of the anatase type, as compared with the case where the crystal structure includes a rutile type or a brookite type (orthorhombic crystal), The photocatalytic action (photocatalytic reactivity) is strong.
Since the semiconductor light emitting device 1 of the present embodiment includes the titanium oxide-based conductive film layer 15 having a strong photocatalytic action, the semiconductor light emitting device 1 is sealed with a sealing resin that is an organic substance without providing a photocatalytic reaction suppressing means. If the lamp is stopped and the lamp is formed, the sealing resin is decomposed by the photocatalytic action of the titanium oxide conductive film layer 15, which may adversely affect the semiconductor light emitting device 1.

For this reason, it is preferable that the semiconductor light emitting device 1 of the present embodiment includes a photocatalytic reaction suppressing unit that suppresses the photocatalytic reactivity of the titanium oxide-based conductive film 15. The photocatalytic reaction suppression means may be any means as long as it can suppress the photocatalytic reactivity of the titanium oxide-based conductive film 15, and is not particularly limited. However, as the photocatalytic reaction suppression means, for example, the photocatalytic reactivity is suppressed. It is preferable to provide a titanium oxide-based conductive film 15 containing an element and / or to provide a protective film 16 that functions as a photocatalytic reaction preventing layer.
Examples of elements that suppress the photocatalytic reactivity contained in the titanium oxide-based conductive film 15 include iron, aluminum, magnesium, and zirconium. The content of the element that suppresses the photocatalytic reactivity contained in the titanium oxide-based conductive film 15 is not particularly limited, and a range in which the conductivity and permeability of the titanium oxide-based conductive film 15 can be sufficiently obtained. Is done.

The titanium oxide based conductive film layer 15 preferably contains at least one element selected from Ta, Nb, V, Mo, W, and Sb. Further, the titanium oxide-based conductive film layer 15 is made of Ti _1-x A _x O ₂ (A = Ta, Nb, V, Mo, W, Sb, X = 1 to 20 at%, preferably X = 2 to 10 at%). More preferably, it consists of When X in Ti _1-x A _x O ₂ is less than 1 at%, the effect of improving the conductivity by adding element A may not be sufficiently obtained. Moreover, when X in Ti _1-x A _x O ₂ exceeds 20 at%, the transmittance at a wavelength of 300 to 550 nm may be lowered, and the output of the semiconductor light emitting device 1 may be insufficient.
The refractive index of Ti _1-x A _x O ₂ (A = Ta, Nb, V, Mo, W, Sb, X = 1 to 20 at%) is in the range of 2.2 to 2.8, preferably Is 2.6.

Further, the titanium oxide conductive film layer 15 made of Ti _1-x A _x O ₂ (A = Ta, Nb, V, Mo, W, Sb, X = 1 to 20 at%, preferably X = 2 to 10 at%). Is preferably in an oxygen deficient state. The conductivity of the film made of Ti _1-x A _x O ₂ (A = Ta, Nb, V, Mo, W, Sb, X = 1 to 20 at%, preferably X = 2 to 10 at%) depends on the oxygen composition. It changes, and the conductivity can be improved by making the oxygen deficient state.

The titanium oxide-based conductive film layer 15 is more preferably made of Ti _1-x A _x O ₂ (A = Nb, X = 3 to 9 at%). When such a titanium oxide-based conductive film layer 15 is used, it has excellent transmittance at a wavelength in the range of 300 to 550 nm and also has good conductivity.

  The film thickness of the titanium oxide based conductive film layer 15 is preferably 35 nm to 2000 nm, more preferably 50 nm to 1000 nm, and most preferably 100 nm to 500 nm. When the film thickness of the titanium oxide-based conductive film layer 15 is less than 35 nm, the current diffusion efficiency may be insufficient and sufficient conductivity may not be obtained. When the film thickness of the titanium oxide-based conductive film layer 15 exceeds 2000 nm, the transmittance decreases, the light extraction efficiency decreases, and the output of the semiconductor light emitting element 1 may become insufficient. When the film thickness of the titanium oxide-based conductive film layer 15 is in the range of 35 to 2000 nm, the semiconductor light-emitting element 1 having a low driving voltage and excellent light extraction efficiency is obtained because good conductivity is obtained.

<Positive electrode>
The positive electrode 17 is formed on one surface 15 a of the titanium oxide conductive film layer 15. The positive electrode 17 is used as a bonding pad. As the positive electrode 17, various structures using known materials such as Au, Al, Ni, and Cu can be used without any limitation. The thickness of the positive electrode 17 is preferably 100 nm to 10 μm, and more preferably 300 nm to 3 μm. By setting the thickness of the positive electrode 17 to 300 nm or more, bondability as a bonding pad can be improved. Moreover, manufacturing cost can be reduced by making the thickness of the positive electrode 17 into 3 micrometers or less.

<Negative electrode>
The negative electrode 18 is in contact with the n-type semiconductor layer 12 by being formed on the exposed surface 12 a of the n-type semiconductor layer 12. The negative electrode 18 is used as a bonding pad. As the negative electrode 18, various known compositions and structures can be used without any limitation.

<Protective film>
The protective film 16 prevents moisture and the like from entering the semiconductor light emitting element 1 and suppresses deterioration of the semiconductor light emitting element 1. Further, the protective film 16 functions as a photocatalytic reaction suppression means for preventing the photocatalytic action of the titanium oxide-based conductive film layer 15 by preventing the entry of moisture or the like into the interface between the protective film 16 and the zirconium oxide layer 39. have.

As the protective film 16, an insulating transparent film having insulating properties is used. The insulating transparent film used for the protective film 16 is a difference between the refractive index and the refractive index of the titanium oxide-based conductive film layer 15 (with a refractive index in the range of 2.2 to 2.8, preferably 2.6). It is preferable that the material is small. Specifically, the protective film 16 is made of Nb ₂ O ₅ (refractive index 2.3), Ta ₂ O ₅ (refractive index 2.2), TiO ₂ (refractive index 2.6), ZrO ₂ (refractive index 2). .1) is preferably made of a material containing any of the above. Since Nb ₂ O ₅ , Ta ₂ O ₅ , TiO ₂ , and ZrO ₂ are materials having a small difference in refractive index from the titanium oxide-based conductive film layer 15, excellent light extraction efficiency can be obtained.

Moreover, it is preferable that the protective film 16 has irregularities formed on at least a part of its surface. By setting it as such a protective film 16, the light extraction efficiency of the semiconductor light-emitting device 1 can be further improved.
The shape of the unevenness formed on the protective film 16 is not particularly limited. For example, a part of or the entire surface of the protective film 16 is provided with a predetermined pitch and a predetermined depth (or height). It can be set as the pattern which consists of the formed line-shaped or dot-shaped recessed part (or convex part).

  Although the film thickness of the protective film 16 is not specifically limited, For example, when the protective film 16 is a uniform film having a flat surface, it is preferably in the range of 10 nm to 10 μm. In the case where the protective film 16 has a uniform thickness and a flat surface, if the film thickness is less than the above range, intrusion of moisture and the like cannot be sufficiently prevented, and the effect of providing the protective film 16 May not be sufficient. In addition, when the protective film 16 has a uniform film thickness with a flat surface, if the film thickness exceeds the above range, productivity may be hindered.

  Further, when the protective film 16 has irregularities formed on at least a part of the surface, the film thickness of the thinnest part is preferably in the range of 10 nm to 100 nm, and the film thickness of the thickest part is The range of 100 nm to 1000 nm is preferable. When the protective film 16 has irregularities formed on at least a part of its surface, if the film thickness is within the above range, the GaN-based compound semiconductor and the electrode layer are exposed to the external environment even at the thinnest film thickness. The effect of protecting against light is sufficiently obtained, and the aspect ratio of the unevenness due to the difference in film thickness between the thin and thick portions can be increased, and excellent light extraction efficiency can be obtained.

"Manufacturing method of semiconductor light emitting device"
Next, as a method for manufacturing the semiconductor light emitting device of the present invention, the method for manufacturing the semiconductor light emitting device 1 shown in FIGS. 1 and 2 will be described as an example.
3 to 7 are manufacturing process diagrams for explaining an example of a method for manufacturing the semiconductor light emitting device shown in FIGS. In order to manufacture the semiconductor light emitting device 1 shown in FIGS. 1 and 2, first, a GaN-based compound semiconductor is formed on the one surface 11a of the substrate 11, and the n-type is formed on the one surface 11a of the substrate 11 as shown in FIG. The semiconductor layer 12, the light emitting layer 13, and the p-type semiconductor layer 14 are laminated in this order.

  The method for forming the GaN-based compound semiconductor that constitutes the n-type semiconductor layer 12, the light emitting layer 13, and the p-type semiconductor layer 14 is not particularly limited, and MOCVD (metal organic chemical vapor deposition), HVPE (hydride vapor phase epitaxy). Method), MBE (molecular beam epitaxy method) and the like can be applied. As a method for forming a GaN-based compound semiconductor, it is preferable to use the MOCVD method from the viewpoints of film thickness controllability and mass productivity.

When MOCVD is used as a method for forming a GaN-based compound semiconductor, hydrogen (H ₂ ), nitrogen (N ₂ ), or the like can be used as a carrier gas, and trimethylgallium (TMG) or triethyl as a Ga source that is a group III material. Gallium (TEG), trimethylaluminum (TMA) or triethylaluminum (TEA) as an Al source, trimethylindium (TMI) or triethylindium (TEI) as an In source, ammonia (NH ₃ ) as an N source as a group V source, hydrazine (N ₂ H ₄ ) or the like can be used.

Further, when the MOCVD method is used, monosilane (SiH ₄ ) or disilane (Si ₂ H ₆ ), which is a Si raw material, germanium gas (GeH ₄ ), which is a Ge raw material, or tetramethyl germanium ((CH _3). ) ₄ Ge) and organic germanium compounds such as tetraethyl germanium ((C ₂ H ₅ ) ₄ Ge) can be used.
When MOCVD is used, biscyclopentadienyl magnesium (Cp ₂ Mg), bisethylcyclopentadienyl magnesium (EtCp ₂ Mg), etc., which are Mg raw materials, can be used as the p-type dopant.

  When MBE is used as a method for forming a GaN-based compound semiconductor, elemental germanium can be used as an n-type dopant.

Here, the case where the n-type semiconductor layer 12, the light-emitting layer 13, and the p-type semiconductor layer 14 are formed by growing a GaN-based compound semiconductor using the MOCVD method will be described in detail.
First, as shown in FIG. 3, the buffer layer 31, the base layer 32, the n-type contact layer 33, and the n-type cladding layer 34 are stacked in this order on the one surface 11 a of the substrate 11 to form the n-type semiconductor layer 12. To do.

When forming the n-type semiconductor layer 12 using the MOCVD method, it is preferable that the pressure in the growth furnace is in the range of 15 to 40 kPa.
Further, the growth temperature when the underlayer 32 is grown is preferably 800 to 1200 ° C, and more preferably 1000 to 1200 ° C. By growing the underlayer 32 within the above temperature range using the MOCVD method, the underlayer 32 with good crystallinity can be obtained.
The growth temperature of the n-type contact layer 33 is preferably 800 to 1200 ° C., more preferably 1000 to 1200 ° C., similarly to the growth temperature of the base layer 32.

Next, as shown in FIG. 3, an AlGaN barrier layer and a GaInN well layer are stacked a plurality of times on the n-type semiconductor layer 12, and finally an AlGaN barrier layer is stacked to form a light emitting layer 13 having a multiple quantum well structure. Form.
The growth temperature of the AlGaN barrier layer is preferably 700 ° C. or higher, and more preferably 800 to 1100 ° C. By setting the growth temperature of the AlGaN barrier layer to 800 to 1100 ° C., an AlGaN barrier layer with good crystallinity can be obtained.
The growth temperature of the GaInN well layer is preferably 600 to 900 ° C, more preferably 700 to 900 ° C. By setting the growth temperature of the GaInN well layer to 600 to 900 ° C., a GaInN well layer with good crystallinity can be obtained.
In order to improve the crystallinity of the light emitting layer 13 having the MQW structure composed of the AlGaN barrier layer and the GaInN well layer, the growth temperature at the time of forming the AlGaN barrier layer, the growth temperature at the time of forming the GaInN well layer, Is preferably changed.

  Next, as shown in FIG. 3, a p-type semiconductor layer 14 is formed by stacking a p-type cladding layer 37 and a p-type contact layer 38 on the light emitting layer 13. As a result, a semiconductor light-emitting element in which the n-type semiconductor layer 12, the light-emitting layer 13, and the p-type semiconductor layer 14 are formed on the substrate 11 is obtained.

Next, a zirconium oxide layer 39 is formed on the p-type semiconductor layer 14 by sputtering. In the present embodiment, since the zirconium oxide layer 39 is formed by a sputtering method, or a method of regulating the deposition rate and deposition time, Zr elements included in the range of ^5mg / cm ^{3 ~5g} / cm 3 Thus, a dense zirconium oxide layer 39 having a thickness of 5 nm or less can be easily obtained.
As a target for forming the zirconium oxide layer 39, ZrO ₂ is preferably used. Further, as a sputtering method, it is preferable to perform RF (high frequency) sputtering with argon gas at a power value (electric power) of 500 W applied to the target side. Thereby, as shown in FIG. 4, the semiconductor light emitting element in which each layer up to the zirconium oxide layer 39 is formed is obtained.

Next, the titanium oxide conductive film layer 15 is formed on the zirconium oxide layer 39. As a result, as shown in FIG. 5, a semiconductor light emitting device in which the electrode layer 19 having the zirconium oxide layer 39 and the titanium oxide conductive film layer 15 is formed can be obtained.
In order to form the titanium oxide-based conductive film layer 15, first, a titanium oxide-based film is formed on the zirconium oxide layer 39 by sputtering.

  As a method of forming a titanium oxide-based film using a sputtering method, for example, a target made of a titanium oxide-based material containing a dopant element is used, and the sputtering atmosphere contains at least 0.1 to 10% by volume of oxygen. Further, it is preferable to use a method of forming a sputtering film at a film formation rate of 0.01 to 2 nm / second with the balance being an atmosphere made of an inert gas.

  Examples of the dopant element contained in the target include Ta, Nb, V, Mo, W, and Sb. As for the dopant element contained in a target, it is more preferable that it is a ratio of 20 mass% or less, and it is most preferable that it is a ratio of 15 mass% or less. Moreover, it is preferable that the dopant element contained in the target is contained at a ratio of at least 1% by mass or more so that the effect of improving the conductivity can be sufficiently obtained.

  The sputtering atmosphere preferably contains at least 0.1 to 10% by volume of oxygen with the balance being an inert gas. The oxygen concentration contained in the sputtering atmosphere is more preferably in the range of 0.3 to 5% by volume, and most preferably in the range of 0.3 to 1.6% by volume. When the oxygen concentration contained in the sputtering atmosphere is in the range of 0.1 to 10% by volume, an amorphous titanium oxide film is formed, and an anatase-type titanium oxide conductive film is obtained by annealing this film. It is done. On the other hand, if the oxygen concentration contained in the sputtering atmosphere is less than 0.1% by volume, a rutile type titanium oxide film is formed, and high conductivity cannot be obtained. In addition, when the oxygen concentration contained in the sputtering atmosphere is 10% by volume or more, the dopant is excessively oxidized, which may cause a sharp decrease in the carrier concentration.

Moreover, it is preferable that the film-forming speed | rate at the time of forming into a film by sputtering method is the range of 0.01-2 nm / sec. When the deposition rate of the titanium oxide film is defined as high as in the above range, the amount of oxygen (O ₂ ) taken into the film during deposition is reduced. As a result, the titanium oxide-based conductive film 15 having a low resistivity can be obtained by annealing the titanium oxide-based film after film formation.
The deposition rate of the titanium oxide film is more preferably in the range of 0.05 to 1 nm / second, and most preferably in the range of 0.07 to 0.7 nm / second.

Further, when the titanium oxide film is formed by the sputtering method, the power value (power) applied to the target side is not particularly limited, but is preferably set to 1000 W or more, for example. By applying such high voltage power to the target, the film formation rate can be increased, and the amount of oxygen taken into the film during film formation can be reduced. As a result, the titanium oxide-based conductive film 15 having a lower resistivity can be obtained by annealing the titanium oxide-based film after film formation.
In addition, when the titanium oxide film is formed using the sputtering method, the bias value applied to the substrate 11 side is not particularly limited. For example, the resistivity may be in the range of 0 to 100 W. It is preferable for obtaining a good low titanium oxide-based conductive film layer 15.

Further, as a method of forming a titanium oxide film using a sputtering method, a method of performing reactive sputtering film formation using a target made of a single metal or an alloy metal and introducing oxygen gas may be used. For example, Ti and Ta can be discharged with separate targets, and Ti and Ta can be reacted with oxygen gas in plasma to produce a titanium oxide-based film made of Ti _1-x Ta _x O ₂ .
When a titanium oxide film is formed by sputtering, the substrate 11 may be heated or a bias voltage may be applied to the substrate 11 in order to improve the adhesion and density of the titanium oxide film. Good.

  Next, the titanium oxide film is annealed. By annealing the titanium oxide-based film, the titanium oxide-based conductive film layer 15 having a crystal structure consisting only of the anatase type is formed. The annealing treatment of the titanium oxide film is performed at a temperature of 300 to 500 ° C., and preferably performed at a temperature of 330 to 450 ° C. If the annealing temperature is lower than 300 ° C., the amorphous crystal structure contained in the titanium oxide film cannot be made anatase type, and the titanium oxide conductive film layer 15 whose crystal structure is composed only of anatase type is not possible. May not be obtained. Further, when the annealing temperature exceeds 500 ° C., the crystal structure is changed from the anatase type to the rutile type.

  The annealing treatment of the titanium oxide film may be performed at any stage after the titanium oxide film is formed, and is not particularly limited. Specifically, for example, the titanium oxide film may be annealed immediately after the titanium oxide film is formed, or before or after the step of exposing a part of the n-type semiconductor layer 12 described later. May be.

Next, as a region for forming the negative electrode 18, the n-type contact layer 33 that is a part of the n-type semiconductor layer 12 is exposed by the method described below.
First, a resist is uniformly applied on the entire surface of the titanium oxide-based conductive film layer 15, and the resist in a region where the negative electrode 18 is formed is removed using a known lithography technique, and a known method such as wet etching is used. The titanium oxide conductive film layer 15 and the oxide layer 39 containing a Zr element are etched.

Next, the p-type semiconductor layer 14, the light emitting layer 13, and the n-type semiconductor layer 12 are etched by reactive ion etching using Cl ₂ as an etching gas to expose the n-type contact layer 33. Thereafter, the etching mask is removed by a known method. Thereby, as shown in FIG. 6, the exposed surface 12a from which a part of the n-type semiconductor layer 12 is exposed is exposed.

Next, as shown in FIG. 7, the positive electrode 17 is formed on the one surface 15 a of the titanium oxide conductive film layer 15, and the negative electrode 18 is formed on the exposed surface 12 a of the n-type semiconductor layer 12.
The positive electrode 17 and the negative electrode 18 are formed on the one surface 15a of the titanium oxide-based conductive film layer 15 and the exposed surface 12a of the n-type semiconductor layer 12 using, for example, a well-known procedure such as lift-off and a well-known lamination method. The first layer, the second layer made of Ti, and the third layer made of Au are sequentially laminated to form a positive electrode 17 and a negative electrode 18 having a three-layer structure.

Next, the protective film 16 is formed. The protective film 16 is formed using a known photolithography technique and lift-off technique using a film forming method that can form a dense film such as a sputtering method or a CVD method in a region other than the central portions of the positive electrode 17 and the negative electrode 18. It is preferable. In particular, as a method for forming the protective film 16, it is preferable to use a CVD method capable of obtaining a dense film.
In addition, when forming what has unevenness | corrugation in at least one part of the surface as the protective film 16, the film | membrane used as the protective film 16 is formed, for example using a sputtering method, CVD method, etc., and predetermined on it It can be formed by a method of forming a resist pattern having the following shape and performing dry etching.

  Thereafter, the substrate on which the protective film 16 is formed is divided (chiped), whereby the semiconductor light emitting device 1 shown in FIGS. 1 and 2 is obtained.

The semiconductor light emitting device 1 of the present embodiment is formed on the p-type semiconductor layer 14 as the electrode layer 19 and includes a zirconium oxide layer 39 containing Zr element in the range of 5 mg / cm ³ to 5 g / cm ³ , and zirconium oxide. Since there is provided the titanium oxide-based conductive film layer 15 formed on the layer 39 and having a crystal structure made of only anatase type, the resistivity and light extraction efficiency of the electrode layer 19 are not hindered. An electrode having a sufficiently thin zirconium oxide layer 39 and a titanium oxide-based conductive film layer 15 having a low resistivity capable of obtaining a sufficient current diffusion performance even when the thickness is reduced, and having a low sheet resistance and an excellent light extraction efficiency It will have the layer 19. Therefore, the semiconductor light emitting device 1 of the present embodiment can be driven at a low voltage and has excellent light extraction efficiency.

In this embodiment, when the film thickness of the zirconium oxide layer 39 constituting the semiconductor light emitting element 1 is 5 nm or less, the conductivity between the p-type semiconductor layer 14 and the titanium oxide-based conductive film layer 15 is good. Thus, the driving voltage Vf of the semiconductor light emitting element 1 can be reduced.
In the present embodiment, when the titanium oxide-based conductive film layer 15 includes at least one element selected from Ta, Nb, V, Mo, W, and Sb, the titanium oxide-based conductive film layer 15 is more Since it becomes more excellent in conductivity, it can be driven at a much lower voltage.

  In the present embodiment, when the n-type semiconductor layer 12, the light-emitting layer 13, and the p-type semiconductor layer 14 constituting the semiconductor light-emitting device 1 are made of a GaN-based compound semiconductor, in the wavelength range of 380 to 480 nm. In addition, it is possible to obtain a high optical conversion efficiency of current.

In the present embodiment, when the protective film 16 including any of Nb ₂ O ₅ , Ta ₂ O ₅ , TiO ₂ , and ZrO ₂ is provided on the titanium oxide-based conductive film layer 15, the titanium oxide-based Since the protective layer 16 having a small difference in refractive index from the titanium oxide-based conductive film layer 16 is provided on the conductive film layer 15, the deterioration of the semiconductor light emitting element 1 can be suppressed and the light extraction efficiency can be further improved. Can be improved.
Further, in this embodiment, when the protective film 16 is provided with an uneven surface on at least a part of the surface, the light is incident at an incident angle such that total reflection of light occurs due to a difference in refractive index. However, since the transmittance increases, the light extraction efficiency can be further improved.

  Further, in the method for manufacturing the semiconductor light emitting device 1 of the present embodiment, the n-type semiconductor layer 12, the light emitting layer 13, and the p-type semiconductor layer 14 are stacked in this order on the one surface 11 a of the substrate 11, and then the p-type semiconductor layer 14. A step of forming a zirconium oxide layer 39 by sputtering on the condition of film thickness of 5 nm or less, a step of forming a titanium oxide film by sputtering on the zirconium oxide layer 39, and annealing the titanium oxide film The method includes a step of forming a titanium oxide-based conductive film layer 15 by processing and forming an electrode layer 19 having the zirconium oxide layer 39 and the titanium oxide-based conductive layer 15. As a titanium oxide film, a titanium oxide film having a crystal structure of anatase type and amorphous type is obtained. Those crystal structure low resistivity comprising only anatase type are obtained.

Therefore, according to the method for manufacturing the semiconductor light emitting device 1 of the present embodiment, the zirconium oxide layer 39 that does not hinder the resistivity and light extraction efficiency of the electrode layer 19 and sufficient conductivity even when the thickness is reduced. The electrode layer 19 having a low sheet resistance and an excellent light extraction efficiency is formed, and can be driven at a low voltage and has a high light extraction efficiency. Element 1 is obtained.
Further, in the method for manufacturing the semiconductor light emitting device 1 of the present embodiment, the zirconium oxide layer 39 and the titanium oxide film 15 are formed by the sputtering method, and therefore the zirconium oxide layer 39 and the titanium oxide film 15 are formed by different methods. Compared with the case, it can manufacture efficiently.

"lamp"
Next, as a lamp of the present invention, a lamp provided with the semiconductor light emitting element 1 shown in FIGS. 1 and 2 will be described as an example.
FIG. 8 is a schematic cross-sectional view showing an example of the lamp of the present invention. In the lamp 5 (LED lamp) shown in FIG. 8, the semiconductor light emitting device 1 shown in FIGS. 1 and 2 is bonded to the frames 51 and 52 with wires 53 and 54, and sealed in a shell shape with a mold 55 made of a transparent resin. It has been stopped.

  The lamp 5 of the present embodiment can be manufactured by a conventionally known method using the semiconductor light emitting device 1 shown in FIGS. 1 and 2, for example, by the method shown below. First, the semiconductor light emitting element 1 is bonded to one of the two frames 51 and 52 (the frame 51 in FIG. 8) using a resin or the like, and the positive electrode 17 and the negative electrode 18 of the semiconductor light emitting element 1 are made of gold or the like. The semiconductor light-emitting element 1 is mounted by bonding to the frames 51 and 52 with wires 53 and 54 made of material, respectively. Thereafter, the periphery of the semiconductor light emitting element 1 is sealed with a mold 55 to obtain the lamp 5 or the like.

The lamp of the present invention is not limited to the lamp 5 shown in FIG. For example, the lamp of the present invention may be a lamp that emits white light by mixing the light emission color of the semiconductor light emitting element 1 and the light emission color of the phosphor. In such a lamp, it is preferable to use a mold 55 in which the phosphor is dispersed, or to provide a cover having the phosphor on the lamp so that the emission color of the phosphor can be obtained.
The lamp of the present invention may be a bullet type for general use, a side view type for portable backlight use, a top view type used for a display, or the like.

  Since the lamp 5 of the present embodiment includes the semiconductor light emitting device 1 shown in FIGS. 1 and 2, the lamp 5 can be driven at a low voltage and has an excellent semiconductor light emitting device having excellent light extraction efficiency. .

  In addition, electronic devices such as a backlight, a mobile phone, a display, various panels, a computer, a game machine, and a lighting incorporating the lamp 5 of this embodiment, and a mechanical device such as an automobile incorporating such an electronic device are low. The semiconductor light emitting device 1 that can be driven by voltage and has excellent light extraction efficiency is provided. In particular, in an electronic device driven by a battery such as a backlight, a mobile phone, a display, a game machine, and an illumination, an excellent product including the semiconductor light emitting element 1 that can be driven at a low voltage can be provided.

"Example"
Hereinafter, the method for producing a semiconductor light emitting device of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.
Example 1
The semiconductor light emitting device 1 shown in FIG. 1 was manufactured by the following method.
In the semiconductor light emitting device 1 of the first embodiment, on the substrate 11 made of sapphire, as the n-type semiconductor layer 12, a buffer layer 31 made of AlN, a base layer 32 made of undoped GaN having a thickness of 4 μm, and Si doped by 2 μm in thickness. An n-contact layer 33 made of n-type GaN and an n-cladding layer 34 made of Si-doped n-type Ga _0.97 In _0.03 N having a thickness of 50 nm were formed.

Next, a 5 nm thick Si-doped GaN barrier layer and a 3.5 nm thick Ga _0.85 In _0.15 N well layer are alternately stacked five times on the n-type semiconductor layer 12, and finally the barrier layer The light emitting layer 13 having a multiple quantum well structure provided with the above was formed.
Thereafter, a p-cladding layer 37 made of Mg-doped single layer Al _0.07 Ga _0.93 N having a thickness of 20 nm and a p-contact layer 38 made of Mg-doped p-type GaN having a thickness of 150 nm are formed on the light-emitting layer 13. The p-type semiconductor layer 14 was formed by sequentially stacking.

Subsequently, an oxide layer (zirconium oxide layer) 39 containing a Zr element was formed on the p-type semiconductor layer 14 by sputtering using a ZrO ₂ target under the condition that the Zr element concentration was 4 g / cm ³ . At this time, the power value (power) applied to the target side was 500 W, and RF (high frequency) sputtering with argon gas was performed. The thickness of the oxide layer containing the Zr element was 5 nm.

Next, a 1% by volume target is formed on the zirconium oxide layer 39 by sputtering using a target made of a titanium oxide-based material (Ti _0.95 Nb _0.05 O ₂ ) containing 5.6% by mass of Nb element. A film was formed under an inert gas atmosphere containing oxygen to form a titanium oxide film. The crystal structure of the titanium oxide film formed by sputtering was anatase type and amorphous type.

  Next, the compound semiconductor substrate having this titanium oxide-based film was annealed at 370 ° C. to obtain a titanium oxide-based conductive film layer 15. The crystal structure of the titanium oxide-based conductive film layer 15 obtained here was only anatase type.

Next, in order to form the negative electrode 18, a resist is uniformly applied on the entire surface of the titanium oxide-based conductive film layer 15, and the region where the negative electrode 18 is formed is formed using a known etching technique or lithography technique, and then Cl _2. The titanium oxide conductive film layer 15, the zirconium oxide layer 39, the p-type semiconductor layer 14, the light emitting layer 13, and the n-type semiconductor layer 12 are etched by the reactive ion etching using, and a part of the n-type contact layer 33 is exposed. I let you.

  Next, a positive electrode 17 was formed on one surface 15 a of the titanium oxide conductive film layer 15 and a negative electrode 18 was formed on the exposed surface 12 a of the n-type semiconductor layer 12 using a known lithography technique. At this time, the positive electrode 17 and the negative electrode 18 are formed of a first layer made of Al, a second layer made of Ti, and Au on one surface 15a of the titanium oxide conductive film layer 15 and the exposed surface 12a of the n-type semiconductor layer 12. A positive electrode 17 and a negative electrode 18 made of a laminated film having a three-layer structure in which the third layer was laminated in this order were formed.

Next, a protective film 16 made of Ta ₂ O ₅ is formed to 600 nm in a region excluding the central portions of the positive electrode 17 and the negative electrode 18 by a sputtering method, and then a diameter of 2 μm, a pitch width of 2 μm, and a height by a mask process and a dry etching method. A protective film 16 having a thickness of 100 nm and having a cylindrical convex portion of 500 nm was formed. The plurality of columnar convex portions constituting the protective film 16 were arranged such that at least three convex midpoints formed an equilateral triangle.

  The substrate back surface of the substrate wafer provided with the semiconductor light emitting device thus manufactured is polished by a general method and divided into chips of a predetermined size to obtain the semiconductor light emitting device 1 shown in FIGS. Manufactured.

(Example 2)
The semiconductor of Example 2 is the same as Example 1 except that the thickness of the oxide layer containing Zr element is 2 nm and the concentration of Zr element contained in this oxide layer is 0.5 g / cm ^3. The light emitting device 1 was manufactured.
(Example 3)
A semiconductor light emitting device 1 of Example 3 was manufactured in the same manner as Example 1 except that the concentration of Zr element in the oxide layer containing Zr element was 5 g / cm ³ .

Example 4
The semiconductor light emitting device 1 of Example 4 was manufactured in the same manner as in Example 1 except that the annealing temperature described in Example 1 was set to 450 ° C. and the protective film 16 was changed to Nb ₂ O ₅ .
(Example 5)
The protective film 16 described in Example 4 except that the TiO _2, was manufactured semiconductor light emitting element 1 of Example 5 in the same manner as in Example 4.
(Example 6)
The semiconductor light-emitting element of Example 6 is the same as Example 1 except that the thickness of the oxide layer containing Zr element is 10 nm and the concentration of Zr element contained in this oxide layer is 5 g / cm ^3. 1 was produced.

(Comparative Example 1)
The semiconductor light-emitting element 1 of Comparative Example 1 is the same as Example 1 except that the concentration of Zr element in the oxide layer containing Zr element is 0 g / cm ³ (the oxide layer containing Zr element is not formed). Manufactured.
(Comparative Example 2)
A semiconductor light emitting device 1 of Comparative Example 2 was manufactured in the same manner as in Example 1 except that the annealing temperature described in Example 1 was changed to 600 ° C.

“Zr element concentration of oxide layer containing Zr element” “film of oxide layer containing Zr element” of semiconductor light emitting devices 1 of Examples 1 to 6 and Comparative Examples 1 and 2 manufactured in this way “Thickness” “Crystal structure of titanium oxide (TiO ₂ ) -based film” “Annealing temperature” “Crystal structure of titanium oxide (TiO ₂ ) -based conductive film layer” “Material and refraction of titanium oxide (TiO ₂ ) -based conductive film layer Table 1 summarizes the “rate”, “material and refractive index of the protective film”, and “existence / absence of irregularities in the protective film”.

  The Zr element concentration of the oxide layer containing the Zr element, the crystal structure of the titanium oxide-based film and the titanium oxide-based conductive film layer, and the refractive index of the titanium oxide-based conductive film layer and the protective film were measured by the following methods. .

(Zr element concentration of oxide layer containing Zr element)
Using a secondary ion mass spectrometer (SIMS), the concentration of Zr, Ga, Ti between the p-type semiconductor layer and the titanium oxide conductive film layer is measured, and the average of the oxide layer containing the Zr element is measured. The Zr element concentration (g / cm ³ ) was calculated.

(Crystal structure of titanium oxide film and titanium oxide film)
The crystal structures of the titanium oxide film and the titanium oxide conductive film layer were measured using an X-ray diffraction (XRD) method. Anatase and amorphous TiO ₂ film (thickness: 250 nm as a standard) is formed on a GaN epitaxial wafer, annealed in the temperature range of 300 ° C. to 700 ° C., and then crystal structure using X-ray diffraction (XRD) method It was determined.

(Refractive index of titanium oxide conductive film layer and protective film)
The measurement was performed at a wavelength of 450 nm according to a prism coupling method or a bulk method.

  Further, the semiconductor light emitting element 1 of Examples 1 to 6, Comparative Example 1 and Comparative Example 2 was energized with a probe needle, and the forward voltage (driving voltage: V) at a current application value of 20 mA was measured. Moreover, the light emission output (Po) of the semiconductor light emitting element 1 of Examples 1 to 6, Comparative Example 1 and Comparative Example 2 was measured using a general integrating sphere. The results are shown in Table 1.

As shown in Table 1, in Examples 1 to 6, the driving voltage is lower and the light emission output is higher than in Comparative Example 1 and Comparative Example 2.
Further, in Example 1, the driving voltage is low and the light emission output is high compared to Comparative Example 2 which is different only in that the annealing temperature is set to 600 ° C. It can be presumed that this is because the crystal structure of the titanium oxide-based conductive film layer is only anatase in Example 1 but only rutile in Comparative Example 1 because the annealing temperature is different. .

  The present invention relates to a semiconductor light-emitting device that can be driven at a low voltage and has an excellent light extraction efficiency, a method for manufacturing the semiconductor light-emitting device, a lamp, an electronic device, and a mechanical device. There is a possibility that the semiconductor light-emitting device having efficiency will be used in industries that manufacture and use it.

DESCRIPTION OF SYMBOLS 1 ... Semiconductor light-emitting device, 5 ... Lamp, 11 ... Board | substrate, 11a ... One side, 12 ... N-type semiconductor layer, 13 ... Light emitting layer, 14 ... P-type semiconductor layer, 15 ... Titanium oxide type electrically conductive layer, 15b ... Side surface DESCRIPTION OF SYMBOLS 16 ... Protective film, 17 ... Positive electrode, 17a ... Upper surface peripheral part, 17b ... Side surface, 18 ... Negative electrode, 19 ... Electrode layer, 31 ... Buffer layer, 32 ... Underlayer, 33 ... N-type contact layer, 34 ... N-type clad Layer 37... P-type cladding layer 38... P-type contact layer 39 39 zirconium oxide layer 51 and 52 frame 53 and 54 wire 55 mold.

Claims (12)

On one surface of the substrate, an n-type semiconductor layer, a light emitting layer, a p-type semiconductor layer, and a titanium oxide-based conductive film layer containing anatase-type crystals are laminated in this order,
Between the p-type semiconductor layer and the titanium oxide-based conductive layer, a semiconductor light-emitting, characterized in that the oxide layer containing Zr element in a concentration range of 5mg ^/ cm ³ ~5g / cm 3 is present element.   2. The semiconductor light emitting element according to claim 1, wherein a thickness of the oxide layer containing the Zr element is 5 nm or less.   The said titanium oxide type electrically conductive film layer contains at least 1 or more types of element selected from the group of Ta, Nb, V, Mo, W, Sb, The Claim 1 or Claim 2 characterized by the above-mentioned. Semiconductor light emitting device. The titanium oxide-based conductive film layer is made of Ti _(1-X) Nb _x O ₂ (where X = 0.03 to 0.09). The semiconductor light emitting element as described.   5. The semiconductor light-emitting element according to claim 1, wherein the n-type semiconductor layer, the light-emitting layer, and the p-type semiconductor layer are made of a GaN-based compound semiconductor. The titanium oxide-based conductive film _layer, the _{Nb 2 O 5, Ta 2 O} 5, TiO 2, claims 1 to 5, wherein a protective film containing any of ZrO ₂ is provided The semiconductor light emitting element in any one.   The semiconductor light emitting element according to claim 6, wherein unevenness is formed on at least a part of the surface of the protective film. After laminating an n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer in this order on one surface of the substrate, the Zr element is deposited on the p-type semiconductor layer by a sputtering method in an amount of 5 mg / cm ³ to 5 g / cm ^3. Forming an oxide layer containing a Zr element under conditions existing at a concentration in the range of
Forming a titanium oxide film on the oxide layer containing the Zr element by sputtering;
And a step of forming a titanium oxide-based conductive film layer by annealing the titanium oxide-based film in a range of 300 to 500 ° C. In the step of forming the titanium oxide-based film, the titanium oxide-based film having a crystal structure of anatase type and amorphous type is formed,
9. The method of manufacturing a semiconductor light-emitting element according to claim 8, wherein the titanium oxide-based film is annealed to form a titanium oxide-based conductive film layer having a crystal structure composed only of anatase type.   A lamp comprising the semiconductor light-emitting device according to claim 1.   An electronic device comprising the lamp according to claim 10 incorporated therein.   12. An electronic device according to claim 11, wherein the electronic device is incorporated.

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