JP2002237660A - Method for manufacturing semiconductor light emitting device - Google Patents

Abstract

(57) [Problem] In a light-emitting element including a nitride-based semiconductor having a group V element other than N as a constituent element in a light-emitting layer, deterioration of the light-emitting layer during growth of the light-emitting element has been a problem. SOLUTION: The manufacturing method of the semiconductor light emitting device of the present invention comprises:
Forming a first conductive type nitride-based semiconductor layer on a substrate;
A second step of growing a light-emitting layer having a nitride-based semiconductor containing a group V element other than N as a constituent element at a growth temperature including the temperature T1, and a step of Al _a Ga _1-a N (0.05 ≤a
≦ 1), a third step of growing the denaturation preventing layer at a growth temperature including the temperature T2, and a step of growing the second conductivity type nitride-based semiconductor layer at a growth temperature including the temperature T3 (T1 <T3, T2 <T3). And a third step of growing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a nitride semiconductor light emitting device having excellent light emitting characteristics.

[0002]

2. Description of the Related Art Conventionally, nitride semiconductors have been used or studied as light emitting devices or high power semiconductor devices. In the case of nitride semiconductor light-emitting devices, blue and green light-emitting diodes, blue-violet semiconductor lasers, and the like have been developed by utilizing characteristics that can produce light-emitting devices in a wide color range from blue to orange. I have. Further, studies have been made on a nitride-based semiconductor material having an element other than N as a group V constituent element.
Japanese Patent Application Laid-open No. 4 discloses a light emitting device including a light emitting layer composed of a GaNAs well layer / GaN barrier layer.

[0003]

However, the GaNas / GaN described in Japanese Patent Application Laid-Open No. Hei 10-270804 is disclosed.
In the light emitting layer, a crystal containing As as well as N as a group V element is used for the well layer. This is a hexagonal semiconductor II
Group I element nitride semiconductor (GaN) and group III element arsenide semiconductor (GaAs), which is a cubic (zincblende structure) semiconductor
s), but because of different crystal structures, the mixed crystal semiconductor is a mixed crystal semiconductor based on a group III element nitride semiconductor in which most of the N component is a group V element. In some cases, a group III element nitride semiconductor (Ga
N) tends to cause phase separation such that a group III element arsenide semiconductor (GaAs) is deposited.
Therefore, the present inventors have found that there is a property in which a portion which does not contribute to light emission appears when the cladding layer or the contact layer is grown after the light emitting layer is formed. Therefore, there is a problem that it is difficult to obtain a light emitting element with sufficiently high luminous efficiency.

Accordingly, in the present invention, in a nitride-based semiconductor light-emitting device including a light-emitting layer composed of a nitride-based semiconductor containing an element other than N as a group V element, the deterioration of the crystallinity of the light-emitting layer is considered. The main purpose is to improve the luminous efficiency by suppressing.

[0005]

According to the method of manufacturing a semiconductor light emitting device of the present invention, the above problems are solved by the following constitution.

According to the method of manufacturing a semiconductor light emitting device of the present invention, a first step of growing a first conductivity type nitride-based semiconductor layer on a substrate, and a nitride-based semiconductor layer containing a group V element other than N as a constituent element are provided. A second step of growing a light emitting layer having a semiconductor at a growth temperature including the temperature T1, and Al _a Ga _1-a N (0.05 ≦ a ≦
A third step of growing the denaturation preventing layer comprising 1) at a growth temperature including the temperature T2, and growing the second conductivity type nitride-based semiconductor layer at a growth temperature including a temperature T3 (T1 <T3, T2 <T3). And a third step to be performed in this order.

In the method of manufacturing a semiconductor light emitting device according to the present invention, the light emitting layer is formed as a quantum well structure having a well layer having a thickness of 0.4 to 20 nm.

In the method for manufacturing a semiconductor light emitting device according to the present invention, the denaturation preventing layer has a thickness of 1 to 200 nm.

In the method for manufacturing a semiconductor light emitting device according to the present invention, the group V element other than N is P, and
Is 670 to 930 ° C.

In the method for manufacturing a semiconductor light emitting device of the present invention, the V group element other than N is As,
Is 650 to 900 ° C.

In the method for manufacturing a semiconductor light emitting device according to the present invention, the group V element other than N is Sb,
Is 650 to 900 ° C.

In the method of manufacturing a semiconductor light emitting device according to the present invention, the temperature T2 satisfies T2 ≦ T1 + 200 ° C.

In the method of manufacturing a semiconductor light emitting device according to the present invention, the modification preventing layer is formed while increasing a growth temperature.

In the method for manufacturing a semiconductor light emitting device according to the present invention, a growth interruption period is provided at least before or after the second step.

The anti-denaturation layer is made of AlGaN and needs to contain at least Al with a composition of 0.05. Preferably, 0.05 to 0.70 is good, and more preferably, 0.1 to 0.
50 is preferred. If the Al composition is too large, strain is excessively applied to the peripheral layer of the active layer, and atoms are easily diffused into and diffused from the active layer, which is not preferable. In addition,
Even if AlGaN contains trace amounts of other elements such as B, In, P, As, and Sb to such an extent that the property is not changed, it does not depart from the spirit of the present invention.

The thickness of the denaturation preventing layer is preferably from 1 to 200 nm, particularly preferably from 5 to 100 nm. If the film thickness is too small, it is difficult to prevent the active layer from deteriorating. If the film thickness is too large, it becomes a barrier for carriers involved in light emission, and it is not preferable because it gives lattice distortion to the active layer.

The light emitting layer preferably has a quantum well structure, and preferably contains one or more and ten or less well layers. The quantum well layer has a thickness of 20 nm at 0.4 nm or more.
It preferably has a thickness of not more than nm. The barrier layer preferably has a thickness of 1 nm or more and 20 nm or less.

At least one of the well layer and the barrier layer is made of S
i, O, S, Se, C, Ge, Be, Zn, Cd and
At least one dopant selected from Mg is added
It may be. The amount of such dopants added is
1 × 10¹⁶~ 1 × 10²⁰/ Cm ^ThreeWithin the range of
preferable.

In this specification, a nitride-based semiconductor is
It shows that the main element of the group V constituent element is N, and TN _{1 -U} V _U (T is a group III element. B, Al, Ga,
In, Tl. V is a group V element other than N. P, As,
Sb. However, it is a semiconductor represented by 0 ≦ U ≦ 0.3). Even in the case of a semiconductor containing N in the group V element, a material in which an element other than N, for example, As, P, or the like is a main element has a different base material. The properties are different from those of the system-based semiconductor and are not included in the nitride-based semiconductor. As a substrate material of the nitride-based semiconductor light emitting device, GaN can be preferably used. The nitride-based semiconductor light emitting device as described above includes an optical information reading device, an optical information writing device, an optical pickup device, a laser printer device,
It can be preferably used in various optical devices such as a projector device, a display device, and a white light source device.

In this specification, the term “active layer” particularly refers to a light emitting layer of a light emitting device that is a semiconductor laser.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with specific examples. When growing a nitride-based semiconductor crystal layer, GaN, sapphire, 6H
—SiC, 4H—SiC, 3C—SiC, Si, spinel (MgAl ₂ O ₄ ), or the like is used as a substrate material.
Like the GaN substrate, also can also use other substrates made of a nitride-based semiconductor, for example, Al _x Ga _y In _z N
(0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1, x + y + z =
1) A substrate can also be used. In the case of a nitride-based semiconductor laser, a layer having a lower refractive index than the cladding layer needs to be in contact with the outside of the cladding layer in order to make the vertical and transverse modes unimodal, and it is also preferable to use an AlGaN substrate. . Further, Si, O, Cl, S, C, Ge, Zn,
The substrate may be doped with Cd, Mg, or Be. Among these doping materials, Si, Ge, O, and Cl are particularly preferable for the n-type nitride-based semiconductor substrate.

In the following embodiments, the sapphire substrate and the C-plane of the GaN semiconductor ｛0
001} substrate will be described. In addition to the C plane, {11-20},
{1-102} or {1-100} may be used. Further, a substrate having an off angle of about 0.1 to 2 degrees in the plane orientation is preferable because the surface morphology of the semiconductor crystal layer grown thereon becomes good.

As a method of growing a crystal layer, organic gold is used.
Metal vapor phase epitaxy (MOCVD), molecular beam epitaxy (M
BE), hydride vapor phase epitaxy (HVPE), etc.
Commonly used. Among these, nitrides to be produced
Considering the crystallinity and productivity of the base semiconductor layer,
Uses GaN or sapphire as the crystal growth method
Most commonly, the MOCVD method is used.
(Embodiment 1) In this embodiment, the present invention relates to a laser device.
An example in which the present invention is applied will be described. (The denaturation prevention layer is Al
_0.15Ga_0.85N, and the growth temperature of the denaturation preventing layer is active.
Same growth temperature as layer growth, denatured immediately after active layer growth
A prevention layer is formed, and then a heating process is performed. 1) The book
According to the method for manufacturing a nitride semiconductor laser device of the embodiment,
FIG. 3 is a cross-sectional view of the element manufactured. Sapphire as substrate
A substrate (101), and a GaN buffer layer
(102), n-type GaN contact layer (103), n-type
Al_{0. 09}Ga_0.91N cladding layer (104), n-type GaN
A guide layer (105) and an active layer (106) are formed.
On the active layer, Al_0.15Ga_0.85N modification preventing layer (10
7), p-type GaN guide layer (108), p-type Al_0.09G
a_0.91N cladding layer (109), p-type GaN contact
A layer (110) is formed and, after crystal growth, SiO 2 _TwoAbsolute
Edge film (111), p-type electrode (112a), n-type electrode (1
12b) is formed. The substrate may be GaN.

FIG. 2 shows an MO used for crystal growth of a nitride-based semiconductor according to this embodiment and the embodiment described below.
It is the schematic of a CVD apparatus. In the figure, (101) is (00)
This is a sapphire substrate having a (01) plane, which is set on a quartz tray (203) on a carbon susceptor (202). A resistance heating heater also made of carbon is arranged in the susceptor, and the substrate temperature can be controlled by a thermocouple. (204) is a reaction tube made of double quartz, which is water-cooled. The group V raw material uses NH ₃ (209a) as an N supply source, arsine (hereinafter AsH ₃ ) (209b) as an As supply source, and phosphine (hereinafter PH ₃ ) (209c) as a P supply source. As raw materials, trimethylgallium (hereinafter, TMG) (211a), trimethylaluminum (hereinafter, TMA) (211b), and trimethylindium (hereinafter, TMI) (211c) can be N ₂ or H ₂ (21
0) was used by bubbling. Silane (hereinafter, SiH ₄ ) (212) is used as an n-type doping material, and biscyclopentadienyl magnesium (hereinafter, Cp ₂ Mg) (21) is used as a p-type doping material.
1d) was used. As the n-type doping material, disilane (Si ₂ H ₆ ) or germane (G
It is also preferable to use eH ₄ ).

Each raw material is supplied to a mass flow controller (20
In step 8), the flow rate is controlled accurately, mixed with N ₂ or H ₂ (210) as a carrier gas, introduced into the reaction tube (204) from the raw material inlet, and then discharged from the exhaust gas outlet (205) to the pipe (206). ) To the exhaust gas treatment device (207).

Next, a method of manufacturing a laser device according to this embodiment will be described.

First, the substrate (101) is washed and set in a crystal growth apparatus. Substrate is 1100 ° C in H ₂ atmosphere
Heat treatment for about 10 minutes at a temperature of about
Cool down to about 50 ° C. If the temperature is constant, changing the carrier gas N _2, the total flow of N ₂ 10l / min. NH
₃ at 3 l / min. After a few seconds, flow TMG to 20 μmo
1 / min. The GaN buffer layer (102) was grown at a low temperature for one minute. The thickness of the grown film is 30
nm. Thereafter, the supply of TMG was stopped and the temperature was reduced to 1
The temperature was raised to 050 ° C., and TMG was added again at 50 μmol / mi.
n. And SiH ₄ gas at 10 nmol / min. Then, the n-type GaN contact layer (103) is grown by 4 μm.

Next, TMA was added at 10 μmol / min. Additional
0.80μm thick Al _0.09Ga_0.91N of N
A mold cladding layer (104) is grown. Next, the provision of TMA
The supply was stopped, and the n-type GaN guide layer (1
05). After that, lower the substrate temperature to 750 ° C.
6 nm thick In_0.02Ga_0.98With multiple N barrier layers
4 nm thick GaN_1-XAs_X(X = 0.02) of the well layer
An active material having a multiple quantum well structure in which a plurality of layers are alternately stacked
The active layer 106 is formed. In this embodiment, the active layer 106
Is a multiple quantum well structure starting at the barrier layer and ending at the barrier layer
And includes three quantum well layers. These barriers
When growing the layers and well layers, both of them are 1 × 10¹⁸
/ Cm^ThreeSiH so as to have a Si impurity concentration of_FourIs provided
Paid. Between the growth of the barrier layer and the well layer or the well layer
Between 1 second and 180 seconds between the barrier layer growth
An interruption period may be inserted. By doing so, obstacles
The flatness of the wall layer and well layer is improved, and the emission half width is reduced.
Can be After the active layer is grown, TMG is
1 / min. , TMA at 5 μmol / min. , And C
p_TwoMg at 0.10 nmol / min. Supply, 30n
m thickness of Al_0.15Ga_0.85Grow N (107).
That is, the growth temperature of the denaturation preventing layer is the same as the growth temperature of the active layer.
750 ° C. Then, TMG, TMA,
Cp_TwoThe supply of Mg was stopped and NH_ThreeAnd N_TwoIn the atmosphere of
The substrate temperature is raised again to 1050 ° C. Like this
The atmosphere is NH_ThreeAnd N_TwoPreferably included
No. Thereby, a nitride-based material containing a group V element other than N can be used.
The quality of the semiconductor crystal as a light emitting layer is less likely to deteriorate.

After the temperature was raised, TMG was added at 50 μmol / min.
And Cp ₂ Mg at 0.20 nmol / min. Supply, p
A GaN guide layer (108) is grown to a thickness of 0.1 μm. Next, TMA was added at 10 μmol / min. Supply, thickness 0.
5 μm Al _0.09 Ga _0.91 N p-type cladding layer (10
9) grow. Thereafter, the supply of TMA is stopped, and TM
G and Cp ₂ Mg are supplied to form a p-type GaN contact layer (1).
10) is grown 0.05 μm, and after completion, TMG and Cp ₂
The supply of Mg is stopped, and the substrate heating is terminated.

Next, this grown film is etched from the surface to the middle of the p-type cladding layer (109) by photolithography and dry etching techniques to form a ridge stripe of 2.5 μm width, and S is formed outside the ridge stripe.
An iO ₂ insulating film (111) was formed. Also, n from the surface
After forming a groove reaching the p-type GaN contact layer, an n-type electrode (112b) made of Ti / Al is formed on the exposed n-type GaN contact layer, and a p-type made of Pd / Pt / Au bonded to the surface of the p-type GaN contact layer. An electrode (112a) was formed. Examples of the n-electrode material include Ti / Al / M
o / Au or Hf / Au may be used. Further, as the p-type electrode material, Ni / Au, Pd / Mo / Au
May be used.

Next, a laser resonator (Fabry-Perot resonator) having a length of 650 μm was formed by cleaving the wafer. Other than the feedback method of the resonator, DFB
(Distributed Feedback), DB
R (Distributed Bragg Reflect)
tor) may be used.

A dielectric multilayer film of titanium oxide and magnesium fluoride having a reflectance of 70% is formed on one end face of the resonator, and a silicon nitride film having a reflectance of 12% is formed on the front end face. The chip was divided by scribing to produce a laser element.

The characteristics of the laser device thus manufactured were measured.
A, laser continuous oscillation with a low threshold value and high luminous efficiency, with a differential luminous efficiency of 0.95 W / A, was obtained. The operating current at room temperature with an optical output of 35 mW was 51.4 mA, the operating voltage was 4.5 V (input power: 231.3 mW), and the oscillation wavelength was 410 nm. Using the p-type electrode as a semi-transparent metal thin film electrode and injecting a current of 10 mA and observing the state of light emission of the active layer, uniform and even light emission was confirmed.

As a comparative example, a layer corresponding to the denaturation preventing layer of this embodiment is grown at 1050 ° C., which is the same as that of the p-type guide layer and the p-type cladding layer, and other conditions are the same as in this embodiment. In the case of the grown laser element, the threshold current under pulse conditions was about 1 A, and continuous oscillation at room temperature did not occur. When the state of light emission of the active layer was observed in the same manner as described above, unevenness in intensity occurred in the light emission, and dark spots having a diameter of several 10 μm, which did not emit light at all, were found in some places. FIG. 12 compares the light emission pattern (a) from the active layer of the device of the comparative example with the light emission pattern (b) from the active layer of the device of the present embodiment. In FIG. 12A,
Black portions are non-light emitting portions, shaded portions are light emitting but dark portions, and white portions are bright light emitting portions.
On the other hand, in the light emitting pattern (b) of the present embodiment, no non-light emitting portion and no dark portion were observed. In the case of the laser element in which the layer corresponding to the denaturation preventing layer of the present embodiment was formed of GaN, the threshold current was 1 A or more, and unevenness in light emission was observed as described above. Thus, the occurrence of light emission unevenness in the two comparative examples indicates that the active layer has deteriorated in the subsequent crystal growth process.
The emission unevenness observed in this way indicates that there are portions that do not contribute to oscillation in the semiconductor laser and portions that do not contribute to emission in the LED, which significantly deteriorates the emission characteristics of the element. As in the present embodiment, a nitride-based semiconductor crystal in which As is added as a group V element in addition to N is a group III element nitride semiconductor (GaN) among hexagonal crystals having a high N content. Inside, Ga
It has been clarified that there is a tendency to cause phase separation such that a group III element arsenide semiconductor such as As is deposited. This can be confirmed by visually observing the light emission pattern from the active layer of the device in which the light emission unevenness has occurred at a high magnification, that a bright spot emitting light of a different color (red to yellow) from the surroundings can be seen. Such a luminescent spot is weak light emission from fine particles of a group III element arsenide semiconductor such as GaAs having an emission wavelength different from that of the base material (which is perceived as purple or blue). It does not contribute, and also does not contribute to the emission of the required emission color in the LED.

In the nitride-based semiconductor crystal to which a group V element other than N is added, a group III element nitride semiconductor (GaN), which is a hexagonal semiconductor, and a cubic (zinc blend structure) semiconductor Group III element arsenide semiconductor (G
aAs), but because of different crystal structures, the mixed crystal semiconductor is a group III element nitride semiconductor-based mixed crystal semiconductor in which the majority of N is a Group V element. In some cases, a group III element nitride semiconductor (G
aN), group III element arsenide semiconductor (GaAs)
Therefore, when the cladding layer or the contact layer is grown after the formation of the active layer, the active layer is denatured, and a portion not contributing to light emission appears. In order to prevent such denaturation, a layer containing Al is formed as a denaturation preventing layer at a temperature lower than the subsequent crystal growth temperature, so that, in addition to N, As
Thus, it is possible to prevent the light emitting layer containing the nitride-based semiconductor crystal to which is added, from deteriorating. In addition, as a group V element other than N,
This situation was the same when As was changed to P.

The above-mentioned phase separation is performed by using GNP, GaN
Sb, GNAsPSb, InGaNAs, InGaN
It can also occur in other nitride-based semiconductor well layers containing As, P, or Sb in the same manner as N, such as P, InGaNSb, or InGaNAsPSb. It was made clear by the inventors. As described above, the effective mass of electrons and holes is smaller in a well layer of a nitride-based semiconductor containing As, P, or Sb than in an InGaN well layer currently in practical use as an LED or the like. The threshold can be expected to be lower than the conventional laser oscillation threshold current density. Thus, it is expected that a laser element with low power consumption and high output and a long life of the laser element can be realized. However, actually, such a light-emitting layer (active layer) has a property of being easily modified as described above. In order to prevent such denaturation, the layer containing Al is formed as a denaturation preventing layer at a temperature lower than the subsequent crystal growth temperature. Deterioration of the layer could be prevented. Naturally, the effect of the Al-containing layer formed at a low temperature to prevent the light-emitting layer (active layer) from being modified is that a nitride-based semiconductor crystal in which As is added as a group V element in addition to N is used as a barrier layer. The same effect can be obtained even in the case of a light emitting layer that has been used or a so-called bulk light emitting layer (active layer) that is not a quantum well light emitting layer. However, when a bulk light emitting layer is used, the composition fluctuates in the growth direction, so that the effect of the present invention is reduced.

Hereinafter, modified examples or preferred ranges of the first embodiment will be described, but these descriptions are similarly effective in all the embodiments after the second embodiment.

In the present embodiment, the composition of the well layer has been described with the specific one described above.
The content of P or Sb can be adjusted according to the emission wavelength of the intended light-emitting element. For example, in order to obtain a blue-violet emission wavelength near 410 nm, GaN _1-x
As in the case of _x x = 0.02, in the case of y = 0.03, and GaN _1-z Sb z in the case of GaN _1-y P y z =
It may be set to about 0.01. In addition, blue 470 nm
To obtain an emission wavelength in the vicinity is, GaN _1-x As have for _x is _{x = 0.03, GaN 1-y} P in the case of _y y = 0.0
6, and in the case of GaN _{1- z} Sb _z , z may be set to about 0.02. Furthermore, in order to obtain a green emission wavelength near 520 nm, x = _{x in} the case of GaN _1-x As _x
0.05, in case of y = 0.08, and GaN _1-z Sb z in the case of GaN _1-y P y may be the degree of z = 0.03. Furthermore, in order to obtain a red emission wavelength near 650 nm, in the case of GaN _1-x As _x , x = 0.0
7, in the case of the GaN _1-y P y is y = 0.12 and Ga,
In the case of N _1-z Sb _z , z may be set to about 0.04.

Further, in order to obtain a desired emission wavelength when an InGaNAs-based or InGaNP-based semiconductor is used as the well layer, the following should be taken into consideration in accordance with the In content y.
The numerical values shown in Table 1 or Table 2 may be adopted as the value of the content ratio x of As or P. Note that the numerical values of the composition shown here are merely examples, and may vary depending on the structure, size, measurement method, and the like of the light emitting layer. And optimize it.

[0040]

[Table 1]

[0041]

[Table 2]

As described above, As, P, or Sb
Preferred formation conditions for use as a light-emitting layer of a nitride-based semiconductor crystal containing are as follows.

First, when P is used as a group V element other than N, the crystal growth temperature is preferably 670 to 930 ° C., and more preferably 700 to 850 ° C. V other than N
When using As as a group element, 650 to 900 ° C.
Is preferable, and 700-850 degreeC is more preferable. N
When Sb is used as a group V element other than 650,
900 ° C is preferred, and more preferably 690-810 ° C. When the growth temperature is lower than the preferable range, surface migration is suppressed, and N, As or P, S
When the crystallinity of the light-emitting layer containing both b and b decreases, and when the crystallinity is too high, the light-emitting layer is undesirably phase-separated. When the growth temperature is out of the more preferable range, bright spots having a different emission color from the surroundings appear as described above.

In this embodiment, the well layer made of a nitride-based semiconductor containing N and As or P or Sb simultaneously and the barrier layer made of a nitride semiconductor are formed at the same growth temperature. This need not be the same.
A layer containing a group V element other than N in a larger composition,
Forming at a lower temperature is also preferable. For example,
In the present embodiment, the barrier layer is 50 to 1 times smaller than the well layer.
It may be formed at a temperature as high as about 00 ° C.

It is preferable to use a quantum well structure from the viewpoint of stability of composition and improvement of luminous efficiency. In this case, the thickness of the well layer is preferably in the range of 0.4 to 20 nm. If the thickness of the well layer is 20 nm or less, phase separation in the growth direction can be suppressed, and a uniform crystal can be easily obtained. On the other hand, the thickness of the well layer is 0.4 nm.
The reason for this is that if the thickness is smaller than this, the well layer will not function as a light emitting region.

With respect to the addition of impurities in the active layer, in this embodiment, Si was added as an impurity to both the well layer and the barrier layer. However, it may be added to only one of the layers, or both layers may not be added. However, laser oscillation is possible. However, according to the photoluminescence (PL) measurement, when the Si is added to both the well layer and the barrier layer, the PL emission intensity is about 1.2 to 1.4 times stronger than the case where Si is not added. became. Thus, in the light emitting device of the present invention,
It was preferable to add impurities such as Si into the light emitting layer. In this embodiment, Si is added at a concentration of 1 × 10 ¹⁸ / cm ³ , but the same effect can be obtained by adding O, S, C, Ge, etc. in addition to Si. The concentration of these additional atoms is preferably about 1 × 10 ¹⁶ to 1 × 10 ²⁰ / cm ³ . In general, in the case of a laser device, if modulation doping is performed by adding an impurity only to the barrier layer, the threshold current density is reduced because there is no carrier absorption in the well layer. The threshold value of the laser was lower when the impurity was added. This is because each layer promotes crystal growth as a lattice-mismatched system, so there are many crystal defects, and it is better to add impurities to improve crystallinity than to consider carrier absorption by impurities in the well layer. It is considered that this was effective in reducing the laser threshold current density.

As described above, As, P, or Sb
Preferable forming conditions for use as a denaturation preventing layer in a nitride-based semiconductor light emitting layer containing the following are as follows.

The formation temperature of the denaturation preventing layer must be lower than that of the layers formed thereon (p-type light guide layer, p-type clad layer, p-type contact layer). +200 nm depending on the formation temperature of the nitride semiconductor containing As, P, or Sb in the light emitting layer.
It is preferable that the temperature is not higher than ° C. In the present embodiment, the well layer is formed at the same temperature. However, if it is grown at a lower forming temperature than the well layer, the function of preventing the light emitting layer from being denatured becomes stronger. Is particularly effective when a light-emitting layer containing 15% or more of the compound is used, in which composition separation easily occurs. Conversely, it may be formed at a temperature equal to or higher than the formation temperature of the well layer and lower than the layers (p-type light guide layer, p-type clad layer, p-type contact layer) formed thereon. As the absolute value of the formation temperature of the denaturation preventing layer, a temperature of 800 to 950 ° C. can be preferably used. In this case, the crystallinity of the denaturation preventing layer is improved, and the doped M
g is easily activated. Thereby, the carrier concentration of the denaturation preventing layer is improved as compared with this embodiment, and the temperature characteristics of the light emitting element are improved. That is, the change in the characteristic with respect to the temperature change becomes small.

The composition of the modification preventing layer is AlGaN,
It is necessary to contain at least the Al composition 0.05. Al
Is less than 0.05, the same result as in the case where the layer corresponding to the denaturation preventing layer of the present comparative example is GaN is obtained. Preferably, it is 0.05 to 0.70, more preferably 0.1 to 0.50. If the Al composition is too large, strain is excessively applied to the peripheral layer of the active layer, and atoms are easily diffused into and diffused from the active layer, which is not preferable. It is desirable that the denaturation preventing layer is made of AlGaN, but some other elements such as B and so on do not significantly deteriorate the properties of AlGaN as the denaturation preventing layer.
The inclusion of In, P, As, and Sb does not depart from the spirit of the present invention. The degree to which the property is not significantly deteriorated is about １ ／ or less of the Al composition when the contained element is In, and the contained element is P, As,
In the case of Sb, it is about １ ／ or less of the Al composition. The thickness of the denaturation preventing layer is preferably from 1 to 200 nm, particularly preferably from 5 to 1 nm.
00 nm is preferred. If the film thickness is too small, it is difficult to prevent the active layer from deteriorating. If the film thickness is too large, it becomes a barrier for carriers involved in light emission, and it is not preferable because it gives lattice distortion to the active layer.

When the growth is performed from the n-type layer on the growth substrate as in the present embodiment, the denaturation preventing layer is preferably a p-type. In this case, the dopant is Zn or Mg.
The dopant concentration is preferably from 1 × 10 ¹⁶ to 1 × 10 ²² cm ⁻³ , and more preferably from 1 × 10 ¹⁸ to 1 × 10 ²¹ cm ⁻³ . If the dopant concentration is too low, the resistance increases, the operating voltage of the device increases, and the characteristics deteriorate, which is not preferable. If the dopant concentration is too high, the dopant diffuses, and the device characteristics deteriorate, which is not preferable. The dopant is Z
It has been confirmed that it is effective to add n and Mg individually or simultaneously. At the same time, S
It is also preferable to add i and O in a concentration less than the amount of Zn, Mg or the like.

In this embodiment, an example using a sapphire substrate having a (0001) plane has been described. However, sapphire substrates having other planes, such as GaN, SiC, spinel, and mica, can be used. However, it has been confirmed that the same effects as those of the present embodiment appear.

Also, sapphire, GaN, hexagonal SiC
When the c-plane substrate is used, it is more preferable that the vertical direction of the substrate surface (the direction of crystal lamination) and the c-axis of the growth substrate have an off-angle in any direction of 0.1 degree or more and 2 degrees or less. Has an off angle in any direction of 0.1 degrees to 0.3 degrees, the flatness of the denaturation preventing layer is promoted,
It has been confirmed that the characteristics of the element are further improved.

When GaN is used as the substrate, it is not necessary to perform heat treatment in an H ₂ atmosphere and grow the buffer layer at a low temperature, and the temperature is raised by using a carrier gas mainly composed of an inert gas and NH 3. It can be carried out in _three atmospheres and at the same time as the introduction of TMG and / or SiH ₄ from the growth of the underlying GaN film. In this case also, the light emitting device produced has the same effects as the present embodiment.

In this embodiment, the case where a GaN film is grown as a low-temperature buffer layer has been described.
As the low-temperature buffer layer, AlηGa ₁ -ηN (0 ≦ η ≦
Even if 1) is used or ZnO is used, there is no problem in manufacturing a light emitting element, and in each case, the same effect as that of the present embodiment is exhibited.

Further, it has been confirmed that the effect of the denaturation preventing layer of this embodiment has a sufficient effect not only on the nitride semiconductor laser element but also on the characteristics of the light emitting diode. (Embodiment 2) In this embodiment, a result of fabricating a nitride-based semiconductor laser device by changing a growth temperature profile of a denaturation preventing layer will be described.

The cross-sectional view of the film manufactured by the method for manufacturing the nitride-based semiconductor laser device of the present embodiment is the same as FIG. 1 used for describing the first embodiment.

FIGS. 6, 7, 8, 9 and 10 show:
FIG. 3 is a diagram showing a growth temperature profile near the active layer in the method for manufacturing the nitride-based semiconductor laser device according to the first embodiment and the present embodiment.

First, in the case of the growth process of the denaturation preventing layer in the manufacturing method of the nitride-based semiconductor laser device of the first embodiment, the formation of the denaturation preventing layer is completed at the same growth temperature as the active layer growth temperature. After heating, the p-type light guide layer is formed. (FIG. 6) Next, a case of the present embodiment in which a denaturation preventing layer is formed during the temperature rise after the growth of the active layer will be described.

The growth method is the same as that of the first embodiment, except for the modification preventing layer. As shown in FIG. 7, after the active layer was grown, TMG was added at 10 μmol / min. , TM
A at 5 μmol / min. , And Cp ₂ Mg in 0.10
nmol / min. Supply 30 nm thick Al _0.15
A Ga _0.85 N modification preventing layer (107) is grown. afterwards,
The supply of TMA is stopped, and the p-type light guide layer is grown. After that, the growth was continued in the same manner as in Embodiment 1, and after the crystal growth was completed, the grown crystal was processed to produce a laser device.

When the characteristics of this laser device were measured,
Laser continuous oscillation with high luminous efficiency was obtained at a low threshold. The input power at room temperature with an optical output of 35 mW is 225.6 m.
W, which indicates that the performance of the element is higher than that of the comparative example described in the first embodiment. This is probably because the denaturation preventing layer has a portion grown at a higher temperature than that in the first embodiment, and the crystallinity of this layer is improved.

As shown in FIGS. 8 and 9, the temperature rise is started after the active layer growth is completed, and simultaneously with the temperature rise, the denaturation preventing layer is grown. After the growth is interrupted for a certain time, the light guide layer is grown. It has been confirmed that the same effects as those of the present embodiment can be obtained even in the case where this is done. At this time, the same effect can be obtained regardless of whether the growth is interrupted during the heating or at a constant temperature after the heating to the growth temperature of the p-type optical guide layer.

As shown in FIG. 10, after the active layer was grown, the formation of the denaturation preventing layer was completed at the same temperature as the active layer growth temperature, and after the growth was interrupted at the same temperature for a certain time, the temperature was raised. It has been confirmed that the same effect as in the present embodiment can be obtained even when the light guide layer is grown.

FIGS. 6, 7, 8, 9 and 1
In the process shown in FIG. 5, it has been confirmed that the same effect as in the present embodiment can be obtained even when a growth interruption process is inserted after the active layer is grown. The temperature at the time of this interruption may be the same as the active layer growth temperature, or may be during the temperature increase. Further, when the growth is interrupted during the temperature increase, the temperature at which the growth interruption is terminated and the growth of the denaturation preventing layer is started must be lower than the growth temperature of the p-type optical guide layer.

Further, during the growth of the denaturation preventing layer, the growth may be interrupted, and the denaturation preventing layer may be further grown.

The growth may be interrupted two or more times. In this case, it has been confirmed that the same effect as in the present embodiment is obtained even if the composition and the doping concentration of the first modification preventing layer and the second and subsequent modification preventing layers are different. For example, following Al _0.1 Ga _0.9 N, the second modification prevention layer Al
_0.15 Ga _0.85 N, third modification preventing layer Al _0.20 Ga _0.80 N
May be grown. Also, continuously, Al _0.15 Ga _0.85
It may be changed from N to Al _0.20 Ga _0.80 N. During growth of the denaturation preventing layer, two or more types of processes such as constant temperature, temperature rise, and temperature decrease may be combined.

In the present embodiment, the denaturation preventing layer is grown after the growth of the barrier layer of the active layer. However, the growth of the denaturation preventing layer can be performed after the formation of the well layer, and the same effect as in the present embodiment can be obtained. Make sure there is. It has been confirmed that, by providing a growth interruption time after forming the well layer and the barrier layer at the time of forming the active layer and adjusting the crystallinity of the active layer and then forming the denaturation preventing layer, the device characteristics are further improved. .

In this embodiment, the growth start temperature of the denaturation preventing layer during the temperature rise is the same as the growth temperature of the light emitting layer. However, the nitride based material containing As, P, or Sb in the light emitting layer is used. The temperature does not need to be the same as long as it is equal to or higher than the semiconductor growth temperature.
In order to effectively prevent denaturation of these light emitting layers, it is preferable to start the growth from a growth temperature of + 200 ° C. or lower from the growth temperature of the nitride semiconductor containing As, P, or Sb in the light emitting layers. In this embodiment, the growth is started from the same temperature as the well layer. However, if the growth is started from a lower formation temperature than the well layer, the function of preventing the light emitting layer from being denatured becomes stronger. This is effective particularly when a light-emitting layer containing 15% or more of group element is used, particularly when a light-emitting layer in which composition separation easily occurs.

In the case of a light emitting diode, the p-type cladding layer in the above description is hardly required to be used. Therefore, a structure in which the p-type cladding layer is omitted and the same growth method as that of the present embodiment is used. We confirm that it is effective.

In the present embodiment, the case where the growth is interrupted during the growth of the active layer or the denaturation preventing layer or before or after the growth is more than the case where the growth is not interrupted.
The input power was relatively small. This is because, after the growth of the active layer or the denaturation preventing layer, exposure to heat in an N ₂ and NH ₃ atmosphere and a period of time allow the surface flatness of each layer to be promoted due to migration of surface atoms and the like, and the interface is formed. It is considered that the laser became steep and, as a result, the crystallinity of the entire device was improved, so that a laser having a low threshold value and high luminous efficiency was obtained.

The interruption of the growth is preferably from 1 second to 5 minutes, more preferably from 10 seconds to 1 minute. If the interruption time is too short, the effect of expelling the gas decreases, and if the interruption time is too long, the growth surface becomes rough due to re-evaporation or the like, which is not preferable.

In this embodiment, N ₂ and NH ₃ are used as the atmosphere gas during the interruption of the growth. However, it was confirmed that the same effect as that of this embodiment can be obtained by using only N _2. ing.

The process (temperature profile) for forming a denaturation preventing layer described in the present embodiment may be applied to the semiconductor light emitting devices of other embodiments described below. Similar effects were obtained. (Embodiment 3) In this embodiment, an example in which an n-type impurity is added to a denaturation preventing layer will be described. FIG. 3 is a cross-sectional view of a device manufactured by the method for manufacturing a nitride-based semiconductor laser device of the present embodiment.

As a substrate, a sapphire substrate (101) was used, on which a GaN buffer layer (502) and a p-type Ga
N contact layer (503), p-type cladding layer (50
4), p-type GaN guide layer (505), active layer (50
6) is formed. On the active layer, an AlGaN modification preventing layer (Al composition 0.05 or more) (507), an n-type GaN guide layer (508), an n-type cladding layer (509), and an n-type G
An aN contact layer (510) is formed, and after crystal growth, an SiO ₂ insulating film (511) and an n-type electrode (512) are formed.
a), a p-type electrode (512b) is formed.

Next, a method for manufacturing a laser device will be described.

First, the substrate (101) is washed and set in a crystal growth apparatus. Substrate is 1100 ° C in H ₂ atmosphere
Heat treatment for about 10 minutes at a temperature of about
Cool down to about 50 ° C. If the temperature is constant, changing the carrier gas N _2, the total flow of N ₂ 10l / min. NH
₃ at 3 l / min. After a few seconds, flow TMG to 20 μmo
1 / min. The GaN buffer layer (502) was grown at a low temperature for one minute. The thickness of the grown film is 30
nm. Thereafter, the supply of TMG was stopped and the temperature was reduced to 1
The temperature was raised to 050 ° C., and TMG was added again at 50 μmol / mi.
n. And Cp ₂ Mg at 0.20 nmol / min. Then, the p-type GaN contact layer (503) is grown by 4 μm.

Next, TMA was added at 10 μmol / min. Additional
0.80μm thick Al _0.09Ga_0.91N p
A mold cladding layer (504) is grown. Next, the provision of TMA
The supply was stopped, and the p-type GaN guide layer (5
05). Growth of p-type GaN guide layer (505)
Later, Cp_TwoStop supplying Mg and TMG, and reduce the substrate temperature.
When the temperature is lowered to 730 ° C. and the temperature is stabilized,
The same active layer as in No. 1 was similarly grown. After growing the active layer, T
MG at 10 μmol / min. , TMA at 5 μmol /
min. , And SiH_FourIs 10 nmol / min. Supply
And a 30 nm thick Al_0.15Ga_0.85N modification prevention layer
Grow (507). Then, TMG, TMA, Si
H_FourSupply of NH is stopped._ThreeAnd N_TwoSubstrate temperature in the atmosphere
The temperature is again raised to 1050 ° C.

After the temperature was raised, TMG was added at 50 μmol / min.
And SiH ₄ are supplied to grow an n-type GaN guide layer (508) by 0.1 μm. Next, TMA was added at 10 μmol / m.
in. Al _0.09 Ga _0.91 N with thickness of 0.05 μm supplied
The n-type cladding layer (509) is grown. Then, TM
A supply is stopped, TMG and SiH ₄ are supplied, and n-type G
The aN contact layer (510) is grown to a thickness of 0.5 μm, and after completion, the supply of TMG and SiH ₄ is stopped to end the heating of the substrate.

Next, this growth film is etched from the surface to the surface of the n-type cladding layer (509) by photolithography and dry etching techniques to form a ridge stripe having a width of 3 μm.
_{2 An} insulating film (511) is formed, and p-type Ga
After forming a groove reaching the N-contact layer, a p-type electrode (512b) made of Pd / Pt / Au is formed in the exposed p-type GaN contact layer, and an n-type electrode made of Ti / Al joined to the surface of the n-type GaN contact layer. (512a) was formed.

Next, a laser resonator having a length of 650 μm was formed by cleaving the GaN-based crystal. A silicon nitride film having a reflectivity of 12% is formed on the end face of the cavity on the side of the laser emission surface, and a dielectric multilayer film of a titanium oxide film and magnesium fluoride having a reflectivity of 70% is formed on the end face of the opposite cavity. Is formed and finally divided into chips by scribing.
A laser device was manufactured.

When the characteristics of this laser device were measured,
Laser continuous oscillation with high luminous efficiency was obtained at a low threshold. The input power at room temperature with an optical output of 35 mW is 279.7.
mW. The light emission pattern of the active layer of the present embodiment was not uneven, and the effect of preventing the active layer from being denatured was observed as in the first embodiment. (Embodiment 4) In the present embodiment, Al
A description will be given of a result of fabricating a nitride-based semiconductor laser device in which the composition is reduced as approaching the active layer and the p-type guide layer. A cross-sectional view of a film manufactured by the method for manufacturing a nitride-based semiconductor laser device of the present embodiment is shown in Embodiment 1.
This is the same as FIG. 1 used for the description.

FIG. 4 is a diagram showing a change over time in the supply amount of each raw material during growth of the denaturation preventing layer in the method for manufacturing a nitride semiconductor laser device of the present embodiment. The growth method other than the time of forming the denaturation preventing layer is the same as that of the first embodiment.

After growing the active layer, the growth temperature is
As shown in FIG. 4, TMG was added at 10 μmol / min. , Cp
₂ Mg at 0.10 nmol / min. , TMA, and a 30 nm thick AlGaN anti-denaturation layer (107)
Grow. The Al composition of the formed AlGaN modification preventing layer was 0.05 at a low position and 0.3 at a high position. Thereafter, the supply of TMA is stopped, and the substrate temperature is raised again to 1050 ° C. in an atmosphere of NH ₃ and N ₂ .

After the temperature was raised, TMG was added at 50 μmol / min.
And Cp ₂ Mg at 0.20 nmol / min. Supply, p
A GaN guide layer (108) is grown to a thickness of 0.1 μm. Thereafter, growth was performed in the same manner as in Embodiment 1, the crystal film was processed, and a laser element was manufactured. After the growth was completed, the grown crystal was processed in the same manner as in Embodiment 1 to produce a laser device.

When the characteristics of this laser device were measured,
Laser continuous oscillation with high luminous efficiency was obtained at a low threshold. Input power at room temperature with an optical output of 35 mW: 211.3 m
It was W, and it was confirmed that the light emission characteristics were improved as compared with a device in which the Al composition of the Al-rich mixed crystal layer of the p-type cladding layer was not changed. Further, the life characteristics were also improved. This is because the Al composition of the denaturation preventing layer is reduced in the range close to the active layer and the light guide layer, and is increased in the middle part to prevent the active layer from deteriorating and to provide the active layer and the light guide layer with a lattice. This is probably because the effect of suppressing the strain and suppressing the diffusion of atoms was exerted, and as a result, the relationship between the input power and the optical output was improved.

Further, in this embodiment, the denaturation preventing layer is grown after the barrier layer of the active layer is grown. However, the growth of the denaturation preventing layer can be performed after the formation of the well layer, and the same effect as in this embodiment can be obtained. Make sure there is. (Embodiment 5) In this embodiment, the cladding layer is formed of In.
_{1-w Ga w N (0} <w <1) incorporating an anti-cracking layer on results of fabricating a nitride-based semiconductor laser device will be described. FIG. 5 is a cross-sectional view of a device manufactured by the method for manufacturing a nitride-based semiconductor laser device of the present embodiment. A sapphire substrate (101) was used as a substrate, and Ga
N buffer layer (102), n-type GaN contact layer (1
03) is formed. An In _0.1 Ga _0.9 N crack preventing layer (713) is formed thereon. An n-type Al _0.09 Ga _0.91 N clad layer (104) is formed on the crack prevention layer, and an n-type GaN guide layer (105), an active layer (106), and an Al _0.15 Ga _0.85 N modification prevention layer are formed thereon. (10
7), p-type GaN guide layer (108), p-type Al _0.09 G
a _0.91 N cladding layer (109) is formed. A p-type GaN contact layer (1) is formed on the p-type cladding layer (109).
10) is formed, and after crystal growth, an SiO ₂ insulating film (111), a p-type electrode (112a), and an n-type electrode (112) are formed.
b) is formed.

The steps up to the formation of the n-type contact layer are the same as in the method of the first embodiment. After the formation of the n-type contact layer, next, the supply of TMA is stopped, and the SiH ₄ is changed to 5.0 nmo.
1 / min. , TMG at 10 μmol / min. , TM
I at 50 μmol / min. Supply In _0.2 Ga _0.8 N
Consisting In _0.1 Ga _0.9 N anti-cracking layer (713) grown to a thickness of 0.1 [mu] m. Then, TM
A at 10 μmol / min. Additional supply, 0.80 thickness
μm Al _0.09 Ga _0.91 N n-type cladding layer (104)
Grow. Subsequent steps are performed in the same manner as in the first embodiment, and the n-type GaN guide layer (105), the active layer (106),
l _0.15 Ga _0.85 N denaturation preventing layer (107), p-type GaN guide layer (108), p-type Al _0.09 Ga _0.91 N cladding layer (109), the growth of the p-type GaN contact layer (110), a crystal film After processing, a laser element was manufactured.

When the characteristics of this laser device were measured,
Laser continuous oscillation with high luminous efficiency was obtained at a low threshold. The input power at an optical output of 35 mW was 203.5 mW, and the life characteristics were also improved. The light emission pattern of the active layer of the present embodiment was not uneven, and the effect of preventing the active layer from being denatured was observed as in the first embodiment.

As in this embodiment, Al _0.15 Ga _0.85
When a crack preventing layer was introduced into a light emitting device provided with an N-denaturation preventing layer, the input power required for a light output of 35 mW was reduced. It is considered that the reason for this is that the crack preventing layer reduces the strain, thereby reducing the factors promoting the diffusion of atoms, improving the crystallinity of the active layer, and increasing the effect of preventing denaturation.

In this embodiment, the crack preventing layer
Is inserted between the n-type contact layer and the n-type cladding layer.
However, in addition, during the n-type contact, the n-type clad
Between the layers or between the n-type cladding layer and the n-type guide layer
Also, the same effects as in the present embodiment can be obtained. Also insert
The location is not limited to one. In addition, the p-type contact layer
When growing from a p-type core,
Between the contact layer and the p-type cladding layer, during the p-type contact,
In the p-type cladding layer, or between the p-type cladding layer and the p-type cladding layer.
The same effect as in the present embodiment can be obtained between the layers. (Embodiment 6) In this embodiment, a growth substrate is used.
Using a GaN substrate and applying the present invention, a nitride semiconductor
The result of manufacturing a laser device will be described. FIG.
Is the manufacture of the nitride semiconductor laser device of the present embodiment.
It is sectional drawing of the element manufactured by the method. As a substrate, n
GaN substrate (801) and an n-type GaN layer
(802), n-type Al_0.09Ga_0.91N clad layer (80
3) is formed. n-type Al _0.09Ga_0.91N cladding layer
On top of (803), an n-type GaN guide layer (804)
Layer (805), Al_0.3Ga_0.7N modification preventing layer (80
6), p-type GaN guide layer (807), p-type Al_0.09G
a_0.91An N cladding layer (808) is formed. p-type Al
_0.09Ga_0.91On the N cladding layer (808), p-type Ga
An N contact layer (809) is formed and after crystal growth
And SiO_TwoInsulating film (810), p-type electrode (811
a), an n-type electrode (811b) is formed.

The schematic diagram of the MOCVD apparatus used in the present embodiment is the same as that shown in FIG. 2 used for describing the first embodiment. N-type Ga having (0001) plane as substrate
Using an N substrate, a nitride-based semiconductor layer is grown.

First, the n-type GaN substrate (801) is washed and set in a crystal growth apparatus. The substrate was heated to 1050 ° C. in an NH ₃ atmosphere, and TMG was added at 50 μmol / mi.
n. And SiH ₄ gas at 10 nmol / min. Then, the n-type GaN layer (802) is grown by 4 μm.

Next, TMA was added at 10 μmol / min. Additional supply, n-type n-type Al _0.09 Ga 0.80 μm thick
_{A 0.91} N cladding layer (803) is grown. Next, TMA
Is stopped and an n-type GaN guide layer having a thickness of 0.1 μm is manufactured (804). n-type GaN guide layer (80
4) After the growth, the supply of SiH ₄ and TMG was stopped, the temperature of the substrate was lowered to 730 ° C., and an active layer was grown in the same manner as in the first embodiment. After growing the active layer, TMG was added at 10 μmol / min. , TMA at 9 μmol / mi
n. , And Cp ₂ Mg at 0.10 nmol / min. Then, a 30 nm thick Al _0.3 Ga _0.7 N anti-denaturation layer (806) is grown.

Thereafter, the supply of TMG, TMA and Cp ₂ Mg is stopped, and the substrate temperature is raised to 1050 ° C. again. After the temperature was raised, TMG was added at 50 μmol / min. And Cp ₂ Mg at 0.20 nmol / min. Then, a p-type GaN guide layer (807) is grown by 0.1 μm. Next, TMA is set to 1
0 μmol / min. An additional supply is performed to grow a p-type Al _0.09 Ga _0.91 N cladding layer (808) having a thickness of 0.80 μm. After the growth is completed, supply of TMA is stopped, and TMG and Cp are stopped.
₂ Mg is supplied, the p-type GaN contact layer (809) is grown to 0.1 μm, and after completion, the supply of TMG and Cp ₂ Mg is stopped to end the substrate heating.

Next, this grown film is subjected to photolithography and dry etching techniques to make the GaN-based crystal <1--1.
100> in parallel with the p-type cladding layer (80
8) Etching up to the surface to form a ridge stripe type having a width of 1.6 μm and TiO ₂ outside the ridge stripe
An insulating film (810) is formed, and an n-type electrode (811b) made of Ti / Al and a p-type Ga
A p-type electrode (811a) made of Pd / Au was formed on the surface of the N-contact layer.

Next, a laser resonator having a length of 500 μm was formed by cleaving the GaN-based crystal on the (1-100) plane. A silicon nitride film having a reflectance of 12% is formed on the end face of the resonator on the light emission side, and 70 nm is formed on the end face of the opposite resonator.
%, A dielectric multilayer film of a titanium oxide film and a magnesium fluoride film having a reflectivity of 5% was formed, and finally a chip was divided by scribing to produce a laser device.

When the characteristics of the laser device thus manufactured were measured, the applied power at room temperature with an optical output of 35 mW was 191.3 mW. The light emission pattern of the active layer of the present embodiment was not uneven, and the effect of preventing the active layer from being denatured was observed as in the first embodiment.

In this embodiment, the use of a GaN substrate eliminates the need for an etching step for producing an n-electrode.
Further, since the cleavage directions of the substrate and the element are the same, chip cutting becomes easy, and the yield is greatly improved. (Embodiment 7) A cross-sectional view of a laser device manufactured by a method for manufacturing a nitride semiconductor laser device of this embodiment is shown in FIG.
It is the same as FIG. 1 used in the description of the first embodiment,
This will be described using this. MO used in this embodiment
The schematic diagram of the CVD apparatus is the same as FIG. 2 used for describing the first embodiment. FIG. 6 is a diagram showing a change with time in the supply amount of each raw material during the growth of the denaturation preventing layer in the method for manufacturing a nitride semiconductor laser device of the present embodiment, which is the same as that of the first embodiment shown in FIG. The difference from the first embodiment is that the material of the active layer is different.

Before the growth of the active layer, the method of the first embodiment is used.
Is the same as After growing the n-type GaN guide layer (105),
SiH_FourAnd supply of TMG are stopped, and the temperature of the substrate is reduced to 730.
° C, and when the temperature stabilizes, TMG
ol / min. , TMI of 10 μmol / min. With
Pay, In_0.05Ga_0.95The barrier layer of the active layer made of N is 5
It was grown to a thickness of nm. When growing the active layer,
SiH_FourIs 10 nmol / min. It may flow to the extent.
Thereafter, TMG was added at 10 μmol / min. , TMI to 5
0 μmol / min. , AsH_ThreeTo 10 nmol / mi
n. Supply, In_0.1Ga_0.9N_0.95As_0.05Activity consisting of
The well layer of the active layer was grown to a thickness of 3 nm. So
After that, TMI was added at 10 μmol / min. To In
_0.05Ga _0.95The barrier layer of the active layer made of N is 5 nm thick.
Grew to be. Barrier layer and well to be active layer
Layer growth was repeated, and three multiple quantum well layers were grown.
Later, a barrier layer is finally grown to grow the active layer (106).
finish. After growing the active layer, TMG was added at 10 μmol / m
in. , TMA at 5 μmol / min. , And Cp _TwoM
g of 0.10 nmol / min. Supply, 15nm thickness
Al of SA_0.4Ga_0.6Growing N-denaturation preventing layer (107)
You. Then, TMG, TMA, AsH_Three, Cp_TwoOffer of Mg
Stop feeding, NH_ThreeAnd N_TwoSubstrate temperature again in the atmosphere of
Raise the temperature to 1050 ° C. After that, the same as in the first embodiment
The growth is continued by the method of
The device was manufactured.

The characteristics of the laser device thus manufactured are
As a result of measurement, the input power at room temperature with an optical output of 35 mW is
178.8 mW. The light emission pattern from the active layer
Observation revealed that the mud looks like a case without a denaturation prevention layer.
La could not be seen. (Embodiment 8) In this embodiment, the embodiment
Impurities in the well layer and barrier layer in the active layer in 1 to 7
1 × 10 instead of Si²⁰/ Cm^ThreeOf C was added.
As described above, the well layer and the barrier layer substitute for the impurity Si.
In the case where C is used instead of the active layer, as in each embodiment, the active layer is changed.
The same effect was obtained as in the case of the prevention of the property. (Embodiment 9) In this embodiment, the embodiment 9
The well layer and the barrier layer included in the active layer in 1 to 7 are
Five-period GaN_0.98P_0.02Well layer (2 nm thick) / Al
_0.01In _0.06Ga_0.93Changed to N barrier layer (4nm thickness)
However, as in the respective embodiments, the active layer is prevented from being denatured.
Similar effects were obtained. (Embodiment 10) In this embodiment,
Well layer and barrier included in active layer according to modes 1 to 9
GaN with 10 layers_0.95Sb_0.05Well layer (thickness 0.4
nm) / GaN barrier layer (thickness 1 nm, Al concentration 5 × 10
¹⁸/ Cm^Three), But each of the embodiments
Similarly, the same effect as the prevention of denaturation of the active layer was obtained. (Embodiment 11) In this embodiment,
Well layer and barrier included in active layer according to modes 1 to 9
GaN with two layers_0.97As_0.03Well layer (6 nm thick)
/ In_0.04Al_0.02Ga_0.94N_0.99P_0.01Barrier layer (thickness
6 nm), but the same in each embodiment.
As a result, the same effect as that of the modification of the active layer was obtained. (Embodiment 12) In the present embodiment,
Well layer and barrier included in active layer according to modes 1 to 9
GaN with 4 layers_0.98As_0.02Well layer (4 nm thick)
/ Al_0.01Ga_0.99N_0.99As_0.01Barrier layer (thickness 10n)
m), but the same effect as in each embodiment is obtained.
Obtained. (Embodiment 13) In the present embodiment,
Well layer and barrier included in active layer according to modes 1 to 9
GaN with three layers_0.97P_0.03Well layer (18 nm thick)
/ Al_0.01Ga_0.99N_0.98P_0.02Barrier layer (thickness 20n)
m), but the same effect as in each embodiment is obtained.
Obtained. (Embodiment 14) In the present embodiment,
Well layer and barrier included in active layer according to modes 1 to 9
GaN with three layers_0.97P_0.03Well layer (5 nm thick) /
Al_0.1Ga_{0 .9}N_0.94P_0.06Change to barrier layer (5nm thickness)
I got it. The denaturation preventing layer is made of Al_0.4Ga_0.55In_0.05N
(That is, the composition of In is changed to 1/8 of the Al composition).
However, effects similar to those of the respective examples were obtained. (Embodiment 15) In the present embodiment,
Well layer and barrier included in active layer according to modes 1 to 9
The layer has three periods of In._0.05Ga_0.95N_0.98P_0.02Well layer (thick
4 nm) / Al_0.01In_0.06Ga_0.93N barrier layer (8n
m), but the same effect as in each embodiment is obtained.
Obtained. (Embodiment 16) In the present embodiment,
Well layer and barrier included in active layer according to modes 1 to 9
The layer has five periods of In._0.1Ga_0.9N_0.94As_0.06Well layer (2
nm) / Al _0.01In_0.06Ga_0.93N barrier layer (4 nm)
However, the same effects as in the respective embodiments can be obtained.
Was. (Embodiment 17) In the present embodiment,
Well layer and barrier included in active layer according to modes 1 to 9
5 layers of Al_0.01In_0.1Ga_0.89N_0.94As_0.06
Well layer (2 nm) / Al_0.01In_0.06Ga_0.93N barrier layer
(4 nm), but the same as in each example
The effect was obtained. (Embodiment 18) In the present embodiment,
Well layer and barrier included in active layer according to modes 1 to 9
5 layers of Al_0.01In_0.05Ga_0.94N_0.96P_0.04well
Door layer (4 nm) / Al_0.01In_0.06Ga_0.93N barrier layer
(8 nm), but the same as in each example
The effect was obtained.

[0100]

As described above, by applying the present invention, it is possible to manufacture a nitride-based semiconductor light-emitting device having high luminous efficiency without deterioration of the light-emitting layer.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a device manufactured by a method of manufacturing a nitride-based semiconductor laser device according to a first embodiment.

FIG. 2 is a schematic view of an MOCVD apparatus used for manufacturing a nitride semiconductor laser device of the present invention.

FIG. 3 is a cross-sectional view of a device manufactured by a method of manufacturing a nitride-based semiconductor laser device according to a third embodiment;

FIG. 4 is a diagram showing a change over time in the supply amount of each raw material during growth of a denaturation preventing layer in the method for manufacturing a nitride-based semiconductor laser device according to the fourth embodiment.

FIG. 5 is a cross-sectional view of a device manufactured by a method of manufacturing a nitride-based semiconductor laser device according to a fifth embodiment;

FIG. 6 is a diagram showing a growth temperature profile near an active layer in the method for manufacturing a nitride semiconductor laser device of the first embodiment.

FIG. 7 is a diagram showing a growth temperature profile near an active layer in the method for manufacturing a nitride semiconductor laser device of the second embodiment.

FIG. 8 is a diagram showing a growth temperature profile near an active layer in the method for manufacturing a nitride-based semiconductor laser device of the second embodiment.

FIG. 9 is a diagram showing a growth temperature profile near an active layer in the method for manufacturing a nitride-based semiconductor laser device of the second embodiment.

FIG. 10 is a diagram showing a growth temperature profile near an active layer in the method for manufacturing a nitride semiconductor laser device of the second embodiment.

FIG. 11 is a cross-sectional view of an element manufactured by the method for manufacturing a nitride-based semiconductor laser element according to the sixth embodiment.

FIG. 12 is a diagram showing a light emitting pattern from an active layer of a device manufactured by the method for manufacturing a nitride-based semiconductor laser device of the first embodiment and a comparative example device. (A) is a light emitting pattern of the comparative example device, and (b) is a light emitting pattern of the device of the first embodiment.

[Explanation of symbols]

Reference Signs List 101 sapphire substrate 102 GaN buffer layer 103 n-type GaN contact layer 104 n-type Al _0.09 Ga _0.91 N cladding layer 105 n-type GaN guide layer 106 active layer 107 Al _0.15 Ga _0.85 N degeneration preventing layer 108 p-type GaN guide layer 109 ... p-type Al _0.09 Ga _0.91 n cladding layer 110 ... p-type GaN contact layer 111 ... SiO ₂ insulating film 112a ... p-type electrode 112b ... n-type electrode 502 ... GaN buffer layer 503 ... p-type GaN contact Layer 504: p-type Al _0.09 Ga _0.91 N cladding layer 505: p-type GaN guide layer 506: active layer 507: Al _0.15 Ga _0.85 N modification preventing layer 508: n-type GaN guide layer 509: n-type Al _0.09 Ga _0.91 N cladding Layer 510: n-type GaN contact layer 511: SiO ₂ insulating film 512a: n-type electrode 512b ... p-type electrode 713 ... In _0.1 Ga _0.9 N crack prevention layer 801 ... GaN substrate 802 ... n-type GaN layer 803 ... n-type Al _0.09 Ga _0.91N clad layer 804 ... n-type GaN guide layer 805 ... Active layer 806 ... Al _0.3 Ga _0.7 N anti-denaturation layer 807 p-type GaN guide layer 808 p-type Al _0.09 Ga _0.91 N clad layer 809 p-type GaN contact layer 810 TiO ₂ insulating film 811 a p-type electrode 811 _b n-type electrode

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yuzo Tsuda 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term (reference) 5F045 AA02 AA04 AA05 AB17 AC08 AC19 AD10 AD11 AD12 AD13 AF03 AF04 AF09 CA11 CA12 DA53 DA54 DA55 5F073 AA42 AA45 AA74 BA04 CA07 CB02 DA05 DA24 DA31 EA23 EA28

Claims (9)

[Claims] 1. A first step of growing a nitride semiconductor layer of a first conductivity type on a substrate, and a step of growing a light emitting layer having a nitride semiconductor containing a group V element other than N as a constituent element at a temperature T1. A second step of growing at a growth temperature including Al _a Ga _1-a N
A third step of growing a denaturation preventing layer made of (0.05 ≦ a ≦ 1) at a growth temperature including the temperature T2; and forming a second conductivity type nitride-based semiconductor layer at a temperature T3 (T1 <T3, T2 <T3). A) a third step of growing at a growth temperature including: 2. The light emitting layer according to claim 1, wherein said well layer has a thickness of 0.4 to 2
2. The method according to claim 1, wherein the semiconductor light emitting device is formed as a quantum well structure within a range of 0 nm. 3. The anti-denaturation layer has a thickness of 1 to 200 n.
3. The method according to claim 1, wherein m is m. 4. The group V element other than N is P,
3. The method according to claim 1, wherein the T1 is 670 to 930 ° C. 4. 5. The method according to claim 1, wherein the group V element other than N is As, and the T1 is 650 to 900 ° C. Method. 6. The semiconductor light emitting device according to claim 1, wherein the group V element other than N is Sb, and the T1 is 650 to 900 ° C. Method. 7. The method according to claim 1, wherein T2 satisfies T2 ≦ T1 + 200 ° C. 8. The method according to claim 1, wherein the denaturation preventing layer is formed while increasing a growth temperature. 9. The method for manufacturing a semiconductor light emitting device according to claim 1, wherein a growth interruption period is provided at least before or after said second step.