JP2003282929A - Method of manufacturing light receiving element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a light receiving element having a large area and a high sensibility. <P>SOLUTION: The method of manufacturing the light receiving element includes a process of forming a device structure having a single or a plurality of group III nitride semiconductor layers, each including a light reception region, on a layer which is a base material, by a metal organic vapor phase growth method. In a process of forming a group III nitride associated with the formation of at least the light reception region, at least one of group III metal compounds which are used as a material for a group III element of the group III nitride is an organic metal compound where one or more hydrocarbon groups are directly bonded to the group III element, with the number of carbons included in at least one hydrocarbon group being 2 or above. <P>COPYRIGHT: (C)2004,JPO

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 light receiving element, and more particularly to a deposition technique used when forming a light receiving element having a multilayer structure.

[0002]

2. Description of the Related Art Conventionally, a light receiving element using a group III nitride semiconductor has been manufactured. Since these group III nitride semiconductors are direct transition type semiconductors and their bandgap energy is wide enough to absorb light in the ultraviolet region, they can also be used as the light receiving region of the ultraviolet light receiving element. However, when a highly sensitive light receiving element is required, it is required that the crystal quality of the group III nitride semiconductor for forming the light receiving region is good.
There is a problem that the lattice constant (lattice interval) is mismatched between the group I nitride semiconductor and the underlying substrate (generally a sapphire substrate). If a lattice constant mismatch exists between the two, dislocations are generated in the group III nitride semiconductor growing on the substrate, and photocarriers are trapped by the levels due to the dislocations, resulting in a decrease in photosensitivity. The problem occurs.

In order to overcome the above problems, that is, to improve the crystal quality of the group III nitride semiconductor for forming the light receiving region, the metal organic chemical vapor deposition (MOCV) method is used.
First, an AlN layer deposited at a low temperature (about 600 ° C.), a GaN layer as a crystal improvement layer, and an AlN layer deposited at a low temperature are sequentially formed on a sapphire substrate by using the D method). A structure is provided, and, for example, an n-type semiconductor layer, an i-type semiconductor layer (light receiving region), a p-type semiconductor layer, and the like are sequentially stacked on the underlying structure by using metal organic vapor phase epitaxy (MOVPE method), A device structure in which a light receiving region is formed by one or a plurality of semiconductor layers among them is provided. When such an element structure including a substrate, a base structure, and a device structure is adopted, the influence of lattice mismatch existing between the group III nitride semiconductor and the substrate for forming the device structure may be adversely affected. The crystal quality of the group III nitride semiconductor, which is relaxed and is related to the formation of the light receiving region included in the device structure, can be made relatively good.

Here, metal organic chemical vapor deposition (MOCVD)
Method and MOVPE method), GaN, AlN, Al
As a raw material used for growing a group III nitride semiconductor such as GaN or InAlGaN, trimethylgallium: TMGa is used as a Ga source, trimethylaluminum: TMAl is used as an Al source, and
It was common to use trimethylindium: TMIn as the n source.

[0005]

Here, when the light receiving element is used as a flame sensor, only the light from the flame is received separately from the room light from the sunlight and various lighting devices. It is required to have wavelength selectivity. Specifically, it is required that the sensitivity in the wavelength range of the light to be detected in the flame light is 10,000 times or more the sensitivity in the wavelength range of the light not to be detected and has a certain level of wavelength selectivity. . In the description in this specification, “sensitivity (unit: A / W)” means how much photocurrent (A) is generated with respect to the light intensity (W) applied to the light receiving element. It can be said that the sensitivity is higher as the photocurrent generated is larger when irradiated with light of the same intensity.

As described above, a high performance light receiving element is required to have high wavelength selectivity.
Impurity levels are formed by incorporating carbon atoms contained in each metal-organic compound used as a raw material in the metal-organic vapor phase epitaxy adopted when manufacturing the light-receiving element into each deposited film. It Then, due to the light absorption by the impurity level, there occurs a problem that the sensitivity appears in the wavelength range not to be detected, and thus the sensitivity in the wavelength range of the light to be detected is in the wavelength range of the light not to be detected. There is a problem that it becomes difficult to increase the sensitivity to 10,000 times or more.

The present invention has been made in view of the above problems, and an object thereof is to provide a method for manufacturing a light receiving element having a large area and high sensitivity.

[0008]

A first characteristic structure of a method of manufacturing a light-receiving element according to the present invention for solving the above-mentioned problems is to provide an underlayer as described in claim 1 of the scope of claims. Or a plurality of layers including a light receiving region on the layer
A step of forming a device structure including a group-nitride semiconductor layer by a metal-organic vapor phase epitaxy method. At least one of the group III metal compounds used as a raw material of the element is an organometallic compound in which one or more hydrocarbon groups are directly bonded to the group III element, and at least one of the hydrocarbon groups is The point is that the number of carbon atoms contained is 2 or more.

A second characteristic configuration of the method for producing a light-receiving element according to the present invention for solving the above-mentioned problems is, as described in claim 2 of the scope of the claims, that the light-receiving element is provided on the underlying layer. II for forming at least the light receiving region, including a step of forming a device structure including one or a plurality of group III nitride semiconductor layers including a region by a vapor deposition method.
In the step of forming the group I nitride, at least one of the group III metal compounds used as a raw material of the group III element of the group III nitride has at least one hydrogen atom directly bonded to the group III element. It is a compound that is.

A third characteristic constitution of the method for manufacturing a light-receiving element according to the present invention for solving the above-mentioned problems is, in addition to the second characteristic constitution, as described in claim 3 of the scope of claims. At least one of the group III metal compounds used as a raw material for the group III element of the group III nitride has at least one hydrogen atom and at least one hydrocarbon group directly bonded to the group III element. It is a compound consisting of.

A fourth characteristic configuration of the method for manufacturing a light-receiving element according to the present invention for solving the above-mentioned problems is, in addition to the third characteristic configuration, as described in claim 4 of the scope of claims. The carbon number contained in at least one of the hydrocarbon groups directly bonded to the Group III element is 2 or more.

A fifth characteristic construction of the method for producing a light-receiving element according to the present invention for solving the above-mentioned problems is any one of the first to the fourth as described in claim 5 of the scope of claims. II related to the formation of the light receiving region
This is because the carbon content in the Group I nitride is 1 × 10 ¹⁷ cm ⁻³ or less.

A sixth characteristic configuration of the method for producing a light-receiving element according to the present invention for solving the above-mentioned problems is any one of the first to fifth aspects as described in claim 6 of the scope of claims. In addition to the above characteristic configuration, prior to the step of forming the device structure, a lattice mismatch between the device structure and the substrate, which comprises one or more semiconductor layers on the substrate, is mitigated. This is because it includes a step of forming an underlayer structure by a metal organic chemical vapor deposition method.

The seventh characteristic constitution of the method for manufacturing a light-receiving element according to the present invention for solving the above-mentioned problems is any one of the first to sixth aspects as described in claim 7 of the scope of claims. In addition to the above characteristic configuration, a step of forming antireflection means for reducing the reflectance of incident light in the device structure on the light incident surface side of the device structure is included.

The eighth characteristic construction of the method for producing a light-receiving element according to the present invention for solving the above-mentioned problems is any one of the first to the seventh as described in claim 8 of the scope of claims. II related to the formation of the light receiving region
The band gap energy of the group I nitride is 3.6 eV or more.

A ninth characteristic constitution of the method for manufacturing a light receiving element according to the present invention for solving the above-mentioned problems is, in addition to the eighth characteristic constitution, as described in claim 9 of the scope of claims. In addition, the band gap energy of the group III nitride relating to the formation of the light receiving region is 4.0 eV or less.

The tenth characteristic constitution of the method for manufacturing a light receiving element according to the present invention for solving the above-mentioned problems is, in addition to the eighth characteristic constitution, as described in claim 10 of the scope of claims. In addition, the band gap energy of the group III nitride relating to the formation of the light receiving region is 4.1 eV or more.

An eleventh characteristic constitution of the method for manufacturing a light receiving element according to the present invention for solving the above-mentioned problems is the tenth characteristic constitution as described in claim 11 of the scope of claims. In addition, the band gap energy of the group III nitride for forming the light receiving region is 4.4 eV or more.

The characteristic configuration of the flame sensor according to the present invention for solving the above-mentioned problems is set forth in claim 1 of the scope of claims.
As described in item 2, it is produced by using the method for producing the light-receiving element according to any one of items 8 to 11.

The operation and effect will be described below. According to the first characteristic configuration of the method for manufacturing a light-receiving element according to the present invention,
At least one of the group III metal compounds used as a raw material for the group III element of the group III nitride in the group III nitride formation step for forming the light-receiving region contains at least one of the group III elements. It is an organometallic compound in which a hydrocarbon group is directly bonded, and since at least one of the hydrocarbon groups has 2 or more carbon atoms, it absorbs light when incorporated into a group III nitride. It is possible to reduce the content of carbon in the film, which functions to give unnecessary sensitivity to the light receiving element by forming an impurity level that contributes to the. As a result, it is possible to provide a light-receiving element having good wavelength selectivity and capable of detecting with high sensitivity even when weak light is irradiated.

According to the second characteristic configuration of the method for manufacturing a light receiving element according to the present invention, at least I for forming a light receiving region is formed.
In the step of forming a group II nitride, at least one of the group III metal compounds used as a raw material of the group III element of the group III nitride has at least one hydrogen atom directly bonded to the group III element. Film of carbon, the carbon film acts to form an impurity level that contributes to light absorption when incorporated in a group III nitride, and to have unnecessary sensitivity to the light receiving element. The medium content can be reduced. As a result, the wavelength selectivity is good,
It is possible to provide a light receiving element that can detect with high sensitivity even when weak light is irradiated.

According to the third characteristic constitution of the method for producing a light-receiving element according to the present invention, at least one of the group III metal compounds used as the raw material of the group III element of the group III nitride is III Since it is a compound in which at least one hydrogen atom and at least one hydrocarbon group are directly bonded to a group element, it forms an impurity level that contributes to light absorption when incorporated into a group III nitride. As a result, the content of carbon in the film, which functions to give unnecessary sensitivity to the light receiving element, can be reduced.

According to the fourth characteristic construction of the method for producing a light-receiving element of the present invention, the carbon number contained in at least one of the hydrocarbon groups directly bonded to the group III element is 2 carbon atoms.
From the above, in a carbon film that, when incorporated into a group III nitride, forms an impurity level that contributes to light absorption and has an unnecessary sensitivity to the light-receiving element. The content can be reduced.

According to the fifth characteristic configuration of the method for manufacturing a light receiving element according to the present invention, the carbon content in the group III nitride relating to the formation of the light receiving region is 1 × 10 ¹⁷ cm ^-3 or less.
(EN) Provided is a light-receiving element which has a small number of carbon impurity levels capable of forming a light absorption site, and as a result has good wavelength selectivity and can detect with high sensitivity even when weak light is irradiated. be able to.

According to the sixth characteristic construction of the method for manufacturing a light-receiving element according to the present invention, first, on the substrate, one or a plurality of semiconductor layers to be buffer layers for the device structure are formed by the metal organic chemical vapor deposition method. Since the device structure is formed after being formed on the substrate by the method, the lattice mismatch between the device structure and the substrate is relaxed, and as a result, the crystal quality of the device structure can be improved. it can.

According to the seventh characteristic configuration of the method for producing a light receiving element according to the present invention, since the antireflection means is provided on the incident light side on the light receiving region, the antireflection means is not provided. In comparison, the amount of light (energy amount) incident on the light receiving region can be increased. As a result, it is equivalent to an increase in photoelectric conversion efficiency in the light receiving region, so that it is possible to provide a light receiving element that can detect with high sensitivity even if the intensity of light from the flame is weak.

According to the eighth characteristic construction of the method for manufacturing a light-receiving element according to the present invention, the bandgap energy of the light-receiving region is 3.6 eV or more, which results in a wavelength of about 344 nm.
Light with a wavelength of (3.6 eV) or less, that is, a wavelength of about 344 n
It is possible to obtain a light receiving element capable of selectively detecting flame light appearing in a wavelength range of m or less by the light receiving region.

According to the ninth characteristic configuration of the method for manufacturing a light receiving element according to the present invention, light having an energy of 3.6 eV or more and 4.0 eV or less is absorbed in the light receiving region, so that a wavelength of about 310 nm ( 4.0 eV) to 344 nm
It is possible to satisfactorily detect the light having a wavelength in the range of (3.6 eV), that is, the light emission peak due to the light emission of the OH radical, which is observed when the compound containing the hydrocarbon is burned in the light of the flame. It is possible to obtain a light receiving element that can be obtained.
In particular, when the light receiving element is installed in a closed space such as the inside of an engine, when it is installed outdoors, there must be light such as indoor light and sunlight from various lighting devices that are observed at the same time. Therefore, only the light of the flame can be satisfactorily detected.

According to the tenth characteristic configuration of the method for manufacturing a light receiving element according to the present invention, since the bandgap energy of the light receiving region is 4.1 eV or more, the wavelength is about 300 nm.
It is possible to obtain a light receiving element capable of detecting light having a wavelength of (4.1 eV) or less, that is, light of flame, by the light receiving region. Further, since the light receiving region is not sensitive to light having a wavelength of more than about 300 nm, that is, room light from various lighting devices, the light receiving element is selectively sensitive to flame light. Can be obtained.

According to the eleventh characteristic configuration of the method for manufacturing a light receiving element according to the present invention, since the bandgap energy of the light receiving region is 4.4 eV or more, a wavelength of about 280 n is obtained.
It is possible to obtain a light receiving element capable of detecting light having a wavelength of m (4.4 eV) or less, that is, light of flame, by the light receiving region. Further, since the light receiving region is not sensitive to light having a wavelength of more than about 280 nm, that is, indoor light and sunlight (natural light) from various lighting devices, it is selective to flame light. It is possible to obtain a light receiving element having sensitivity to.

According to the characteristic configuration of the flame sensor according to the present invention, the band gap energy of the group III nitride for forming the light receiving region is adjusted to a value having a selective sensitivity to the light of the flame. At the same time, there is provided a flame sensor having a reduced content of carbon in the film, which acts to give unnecessary sensitivity to the light receiving element. Therefore, the sensitivity in the wavelength range to be detected (range in which flame light is included),
A flame sensor with a large sensitivity difference with the sensitivity in the wavelength range that is not the detection target (range that includes ambient light such as sunlight and room light) can be obtained. Even if there is, it can be detected with high sensitivity by distinguishing its presence from ambient light.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION A method of manufacturing a light receiving element according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of a semiconductor growth apparatus (MOCVD apparatus) in which a light receiving element is manufactured, and the semiconductor growth step will be briefly described below.

The carrier gas tank 1 stores a carrier gas for carrying the raw material stored in the raw material tank 3 to the reaction chamber 4. As the carrier gas, nitrogen gas or hydrogen gas may be used. it can. Oxygen contained in the carrier gas discharged from the carrier gas tank 1 is removed by the oxygen removing device 2. A specific example of the oxygen removing device 2 when hydrogen gas is used as the carrier gas is a hydrogen permeable membrane including a palladium membrane, which is a molecule that is used when hydrogen gas is passed through a metal palladium membrane. It utilizes the characteristic that only hydrogen gas having a small size can selectively pass through the palladium membrane. As a result, the oxygen concentration in the gas supply passage after the oxygen removing device 2 can be reduced to an extremely low level.

After passing through the oxygen removing device 2, the oxygen-free carrier gas flows into the raw material tank 3 after its flow rate is adjusted by the valve V1. In the present embodiment, since a liquid organometallic material is assumed as the raw material, a bubbler is provided in the raw material tank 3 so that the vaporized organometallic raw material reacts with the carrier gas through the valve V2. It can be configured to flow out to the chamber 4 side. Further, when it is desired to dilute the raw material gas, the opening degree of the valve V3 may be adjusted so that only the carrier gas flows into the reaction chamber 4 side. Further, when the raw material is gas, the raw material may be stored in the raw material tank 7 and supplied into the reaction chamber 4 while adjusting the flow rate with the valve V4.

In FIG. 1, the raw material tank 3 is shown for simplification.
Although only one is shown in the figure, when there are a plurality of raw materials, a plurality of raw material tanks 3 may be provided in parallel so that raw material gases whose raw material amounts are adjusted respectively flow into the reaction chamber 4 side. . The amount of the raw material to be flown into the reaction chamber 4 is adjusted by adjusting the opening of the valve V1 provided on the upstream side of each raw material tank 3 to adjust the amount of the gas flowing into the raw material tank 3. This is performed by adjusting the opening degree of the valve V2 provided on the downstream side of the tank 3.

The source gas supplied into the reaction chamber 4 is applied to the crystal growth surface of the substrate 6 placed on the sample holder 5 by the source gas activating means (not shown) provided in the reaction chamber 4. accumulate. Also, the temperature of the substrate 6 is adjusted by heating the sample holder. The inside of the reaction chamber 4 is exhausted and adjusted to a predetermined pressure. Heating means, plasma generating means, etc. are typical means for activating the raw material gas. When the supplied raw material gas contains a plurality of kinds of elements, each activated element forms a compound. Then, it is deposited and grown on the crystal growth surface of the substrate 6. The degree of activation varies depending on the type of raw material gas, and there are organometallic materials that are decomposed near the surface of the substrate 6 and organometallic materials that are decomposed before reaching the surface of the substrate 6. As the substrate material, a material having a good compatibility with the substance to be deposited and grown is used.

By repeating the above semiconductor growth process, a plurality of semiconductor layers are epitaxially grown on the substrate 6, and as a result, a semiconductor laminated structure can be obtained. Further, if necessary, impurities can be implanted to make each semiconductor layer a p-type semiconductor or an n-type semiconductor.

The method for manufacturing the light receiving element according to the present invention will be described in detail below with reference to examples. The light-receiving element 30 shown in FIG. 2 has a base structure provided on the substrate 10 by the metal-organic vapor phase epitaxy method described with reference to FIG. And a device structure provided. The underlying structure is obtained by sequentially depositing the low temperature deposition buffer layer 11, the crystal improvement layer 12, and the low temperature deposition intermediate layer 13 on the substrate 10. Also,
The device structure is such that an n-type semiconductor layer 14 and
The n-type semiconductor layer 14 exposed by sequentially depositing the i-type semiconductor layer 15, which functions as a light receiving region, the p-type semiconductor layer 16, and the p-type contact layer 17, and partially etching these deposited layers. The electrode 18 (negative electrode) is provided on the surface of
It is obtained by providing the electrode 19 (positive electrode) on the surface of the p-type contact layer 17.

As the materials of the substrate, the underlying structure, and the device structure described above, for example, the substrate 10 is sapphire, the low-temperature deposition buffer layer 11 is AlN (thickness 20 nm), and the crystal improvement layer 12 is GaN (thickness). 1 μm), the low temperature deposition intermediate layer 13 is AlN (thickness 20 nm), n
-Type semiconductor layer 14 (thickness 1 μm), i-type semiconductor layer 15 (thickness 100 to 200 nm), and p-type semiconductor layer 16 (thickness 80)
nm) and a single crystal _{In x Al y Ga 1-xy} N (0 ≦ x ≦
1, 0 ≦ y ≦ 1). In addition, the p-type contact layer 17
Is p-GaN or Al having a small aluminum composition ratio y
_y Ga _1-y N (thickness 20 nm). Further, the electrodes 18 and 19 are formed using a metal such as Ti, Ni, Al, Au. In addition, the electrode 18 and the n-type semiconductor layer 14
And the electrical characteristics between the electrode 19 and the p-type contact layer 17 are in an ohmic state. Further, since the light is configured to enter the i-type semiconductor layer 15 from the electrode 19 side, the electrode 19 needs to have a structure capable of transmitting the light. Therefore, the electrode 19 is
It is manufactured in the form of a mesh electrode or a transparent conductive electrode. The above-mentioned film thickness value can be changed to another value according to the application.

The role of the underlying structure is to improve the crystal quality of the device structure. _{In x Al y Ga 1-xy} N (0 ≦ x ≦ 1 constituting the lattice spacing in the crystal growth surface of the sapphire substrate 10, the device structure,
There is a large difference with the lattice constant of 0 ≦ y ≦ 1), but since the lattice mismatch can be relaxed by the underlying structure, the lattice mismatch added when growing InAlGaN forming the device structure. The stress due to matching can be made very small. As a result, the crystal quality of InAlGaN in the device structure can be improved.

By configuring the light receiving element as described above,
The light emitted from the electrode 19 side is incident on the i-type semiconductor layer 15 which functions as a light receiving region, absorbs the light having the energy corresponding to the bandgap energy of the i-type semiconductor layer 15, and generates photocarriers. Then, the electrode 18 and the electrode 1
The photocarrier is extracted as a photocurrent by the reverse bias voltage applied during 9, and the intensity of the received light is derived from the magnitude of the current.

When a light-receiving element composed of a group III nitride is produced as described above, metalorganic vapor phase epitaxy is used for producing each layer, but triethylgallium (TEGa) is used as a gallium source, Triethylaluminum (TEAl) is used as an aluminum source, triethylindium (TEIn) is used as an indium source, and ammonia is used as a nitrogen source. Therefore, referring to FIG. 1, liquids TEGa, TEAl, and TEIn are stored in separate raw material tanks 3, transported to a carrier gas, and supplied to the reaction chamber 4. Further, ammonia is stored in the raw material tank 7 and supplied to the reaction chamber 4. The substrate temperature was set to about 1000 ° C. to form the film.

When an n-type or p-type impurity semiconductor is manufactured using a dopant, disilane or silane is used as a dopant in the case of Si doping, and MeCp ₂ Mg (bismethylcyclo) is used as a dopant in the case of Mg doping. Magnesium pentane) or EtCp ₂ M
g (bisethylcyclopentane magnesium) is used, and Cp ₂ Be is used as a dopant in the case of Be doping.
(Cyclopentane beryllium) or MeCp ₂ Be
(Bismethylcyclopentane beryllium) can be used.

Generally, the group III metal compound used as a raw material for the group III element of the group III nitride is an organic metal compound such as trimethylgallium (TMGa), trimethylaluminum (TMAl), or trimethylindium (TMIn). The number of carbon atoms of one hydrocarbon group of the organometallic compound was 1 (that is, a methyl group). However, in the present embodiment, as described above, the number of carbon atoms contained in one hydrocarbon group is 2 (that is, ethyl group).
By using the organometallic compound of No. 3, as shown in Table 1, it was possible to reduce the carbon content in the obtained group III nitride (AlGaN). This is also the case when InAlGaN is used as the group III nitride.

[0045]

[Table 1]

The results shown in Table 1 are TMGa and TM.
Since Al molecules are relatively stable and decomposed near the substrate, carbon is easily incorporated into the film,
It can be considered that the molecules of TEGa and TEAl are decomposed before reaching the vicinity of the substrate, and the number of carbon radicals reaching the vicinity of the substrate is reduced.

As described above, since the amount of carbon contained in the group III nitride obtained in this embodiment can be reduced, the impurity level of the carbon contributes to light absorption, so that the light-receiving element is not affected. It is possible to prevent the required sensitivity from appearing. As a result, the wavelength selectivity is good,
It is possible to provide a light receiving element that can detect with high sensitivity even when weak light is irradiated. In particular,
When using this light receiving element as a flame sensor used in a situation where the light intensity in the wavelength range to be detected is weak, the sensitivity in the wavelength range of the light to be detected and the wavelength of the light not to be detected Since it is required that the difference between the range and the sensitivity is large, the significance of the present embodiment is large.

[0048] _{Here, In x Al y Ga 1-} xy N (0 ≦ x ≦ 1 constituting the i-type semiconductor layer 15 and n-type semiconductor layer 14 and the p-type semiconductor layer 16, which acts as a light receiving region,
The band gap energy of 0 ≦ y ≦ 1) is adjusted by changing the indium composition ratio x and the aluminum composition ratio y, and the indium composition ratio x and the aluminum composition ratio y are adjusted.
And the band gap energy of InAlGaN are expressed by the relationship shown in FIG. As seen from FIG. 3, by changing the indium composition ratio x and the aluminum composition ratio y, it is possible to adjust the band gap energy of _{In x Al y Ga 1-xy} N from 1.9eV down to 6.2 eV. In other words, the wavelength range of light that can be absorbed in the light receiving region is adjustable between approximately 200 nm and approximately 650 nm. Further, when the light of the flame is detected by the light receiving element, it is sufficient to form the light receiving region having the band gap energy that can absorb the light emission of the flame as shown in the emission spectrum of FIG. The emission spectrum of the flame shown in FIG. 4 is the spectrum of the flame generated when gas (hydrocarbon) is burned. Further, the spectrum of sunlight and the spectrum of room light due to light from various lighting devices are also shown at the same time.

The band gap energy of a preferable light receiving region when used as an ultraviolet light receiving element will be described below. Therefore, in order to increase the band gap energy, description will be made assuming that indium is not included (indium composition ratio x = 0).

[0050] In order to provide wavelength selectivity to the light-receiving element, by adjusting the composition ratio of Al in the light receiving area _{(Al y Ga 1-y N} ), to set the band gap energy to a desired value Done. For example, when it is desired to manufacture a flame sensor capable of selectively receiving flame light that appears with a relatively large intensity in a wavelength range of about 344 nm or less, the bandgap energy of the light receiving region is 3.6 eV.
The aluminum composition ratio y may be set to y = 0.05 or more so as to be the above. Alternatively, light from various lighting devices (room light) included in the wavelength range of about 300 nm or more.
When it is desired to manufacture a flame sensor that receives the light of the flame within the detection target wavelength range without receiving the light, the aluminum composition ratio y = 0 so that the bandgap energy of the light receiving region is 4.1 eV or more. 0.25 or more. Alternatively, when it is desired to manufacture a flame sensor that receives only the light of the flame within the detection target wavelength range without receiving the light from sunlight included in the wavelength range of about 280 nm or more, the light receiving region Of aluminum composition ratio y such that the band gap energy of
= 0.35, or higher.

Alternatively, if ambient light such as sunlight may be absorbed in the light-receiving region as long as the light intensity is weak, the bandgap energy in the light-receiving region is 4.3 eV or more (wavelength of about 290 nm or less). Thus, the aluminum composition ratio y should be 0.31 or more. When the wavelength is about 290 nm or less, the light intensity of the ambient light becomes very small as shown in FIG. 4, and the light of the flame is large on the other hand, and as a result, the presence of the light of the flame can be detected.

Further, when the light receiving element is installed in a closed space such as the inside of an engine and it is desired to detect the light emission of the fuel burned therein, the above-mentioned room light and sunlight are not present, so that they are excluded. It is not necessary to set a large bandgap energy. Therefore, among the light of the flame in the detection target wavelength range, a light emission peak (wavelength of approximately 310 nm (wavelength of about 310 nm ( 310 nm ± 10 nm): 4.0 eV)
Light (light of flame with wavelength of 310nm to 344nm)
When a light receiving element capable of selectively receiving light is produced, the bandgap energy of the light receiving region is 3.6e.
The aluminum composition ratio y may be set to 0.05 or more and 0.23 or less so as to be V or more and 4.0 eV or less.

The relationship between the indium composition ratio x and the aluminum composition ratio y and the bandgap energy of InAlGaN described above is based on the theoretical values, and the indium composition ratio x and the aluminum composition ratio y are the same as the theoretical values. Even if the film is formed as described above, the band gap energy of the InAlGaN layer actually obtained may be different. For example, AlGaN which is a ternary mixed crystal compound
In the case of, the binary compound GaN is easily generated,
As a result, the band gap energy tends to shift to the low energy side (long wavelength side). Therefore, when it is desired to obtain the bandgap energy according to the theoretical value, the aluminum composition ratio may be set to a large value before the film formation.

As described above, the band gap of the light receiving region in the device structure is adjusted to receive light of a desired wavelength. However, a portion other than the light receiving region (for example, the p-type shown in FIG. 2) has been described. When the band gap energy of the semiconductor layer and the n-type semiconductor layer) is designed to be equal to or larger than the band gap energy of the light receiving region, another effect can be obtained. In other words, the portion other than the light receiving region can be used as a window for the light receiving region, which has good light transmission characteristics, so that the intensity of light incident on the light receiving region can be secured to be large. Therefore, even if the light applied to the light receiving element from the outside is weak, it is possible to reach the light receiving region without attenuating the light intensity.

Further, since the content of carbon in the film forming the impurity level which can be a light absorption site is required to be reduced at least in the i-type semiconductor layer 15 which functions as a light receiving region, it is necessary to form the light receiving region. The method for forming a light receiving element according to the present invention can be applied only when forming such a group III nitride semiconductor. However, the formation of the light receiving element according to the present invention is also performed when forming a semiconductor layer (a semiconductor layer located within the diffusion distance of the photocarriers from the light receiving region), which is arranged so as to sandwich the group III nitride semiconductor in the formation of the light receiving region. It is preferable to apply the method, and in that case, the difference between the sensitivity in the wavelength range of light to be detected by the light receiving element obtained and the sensitivity in the wavelength range of light not to be detected can be increased.

<Other Embodiments><1> The configuration of the light receiving element has been described above. However, there is a problem that the light is reflected on the surface of the element and the intensity of the light incident on the light receiving region becomes small. The provision of the antireflection function for preventing the light receiving element will be described with reference to FIG.

FIG. 5A is a configuration diagram of the light receiving element 31 having an antireflection function, and FIG. 5B is an explanatory diagram of the antireflection function portion shown in FIG. 5A. 5C is an explanatory diagram of a comparative example in the case where the antireflection function is not provided.

First, the light receiving element 31 shown in FIG.
It is similar to the element structure illustrated in FIG. The difference is that
Structure of pole 19 and p-type capacitor without electrode 19
Acts as an antireflection means on the portion on the tact layer 17.
The point is that the light transmitting layer 20 is provided. Used here
The light transmission layer 20 is made of Al_yGa_1-yN (0 ≦ y ≦ 1)
The refractive index can be adjusted by changing the atomic composition.
You can In addition, magnesium fluoride (MgF₂),
Calcium fluoride (CaF₂), Silicon dioxide (SiO ₂)etc
Can be used. In addition, Al_yGa_1-yWhen using N
In the case of
There is an advantage that you can.

FIG. 5B is a diagram for explaining an antireflection function portion provided on the semiconductor structure in the light receiving element 31 shown in FIG. 5A. In the figure, the refractive index in air is n ₀ , the refractive index of the light transmitting layer is n ₁ (n ₁ > n ₀ ), and the refractive index of the p-type contact layer 17 is n ₂ (n ₂ > n ₁ ). . Further, as a comparative example, FIG. 5C illustrates reflection when the antireflection function is not provided.

First, FIG. 5A and FIG. 5B are shown.
As described above, the p-type contact layer 17 and the light transmission layer 20 are provided.
When the light transmission layer 20 is exposed to the air,
The light transmission layer 20 is not provided, and the p-type contact layer 1
For two cases where 7 is exposed to the air, p-type
Reflectance for incident light perpendicularly incident on the contact layer 17
R₁And R₂Are shown in Equations 1 and 2 below. here,
Thickness d of the light transmission layer 20 ₂₀Measures the quarter wavelength of the incident light.
Value divided by the refractive index of the body: d₂₀= Λ (incident light) / 4n₁To
Is set. The wavelength of the incident light is the
The wavelength is, for example, 260 nm corresponding to the light of a flame.
The wavelength is 280 nm.

[0061]

[Formula 1] R ₁ = (n ₀ · n ₂ −n ₁ ) ² / (n ₀ · n ₂ + n ₁ ) ²

[0062]

## EQU2 ## R ₂ = (n ₀ −n ₂ ) ² / (n ₀ + n ₂ ) ²

Here, the refractive index n of the p-type contact layer 17 is
₂Is the refractive index n of the light transmitting layer 20.₁Is greater than
n₀If = 1, by comparing equation 1 and equation 2, R₂
> R ₁It turns out that Therefore, the light transmission layer 20 is provided.
Intensity of light incident on the p-type contact layer 17 in the case of
Is incident on the p-type contact layer 17 when not provided.
The light conversion efficiency of the light receiving element is
The rate can be increased. As a result, Teru
The emitted light can be efficiently introduced into the light receiving area.
A light receiving element is provided.

<2> In the above embodiment, the electrode 1
8 and electrodes 19 are made of Ti, Ni, Al, Au
Although it has been described that a metal such as the above can be used, other materials may be used. For example, ZrB ₂ can be used as an electrode. ZrB _{2 which} is the material of the electrode is
Ion beam sputtering, laser ablation, CVD
Can be prepared by a vapor deposition method such as Zr [N (C ₂ H ₅ ) ₂ ] ₄ or Zr (BH ₄ ) ₄ as a Zr source.
1 to produce ZrB ₂ using the MOCVD method using trimethylboron as the B source.
There is an advantage that the film forming apparatus described with reference to can be used to form the film in a process similar to that of the group III nitride.
Incidentally, Al on the ZrB ₂ electrode prepared, Au, Ni, T
A metal such as i may be further formed to form a multi-layer electrode that protects the ZrB ₂ electrode.

Furthermore, ZrB is used as the electrode material.₂When using
The ohmic characteristics of the underlying semiconductor layer.
It has the advantage that it can be example
For example, use Al, Au, Ni, Ti, etc. as the electrode material.
In these materials, In _xAl_yGa_1-xyN layer
The electrical characteristics between (0 ≦ x ≦ 1, 0 ≦ y ≦ 1)
In order to obtain a strong one, the aluminum composition ratio y
Was required to be small. However, the material of the electrode
ZrB as a fee₂If you use
The composition ratio is not limited, and the aluminum composition ratio y is large.
In this case also, the electrical properties of the interface between the electrode and the InAlGaN layer
The characteristics can be ohmic.

<3> In the above-described embodiment, one hydrocarbon group contained in all the group III metal compounds used as the raw material for the group III nitride semiconductor has 2 carbon atoms.
Although the case has been described above, the present invention is not limited to this. For example, instead of using TEGa as a gallium source, TEAl as an aluminum source and TEIn as an indium source for forming a film, a modification such as using TMGa only for the gallium source, or for the gallium source, Modifications such as using TMGa, using TMAl for the aluminum source and using TEIn for the indium source, or other combinations are possible.

In the above-mentioned embodiment, one hydrocarbon group of the group III metal compound used as a raw material for the group III element (Al, Ga, In, etc.) of the group III nitride has 3 carbon atoms. Even if it is above, the same effect can be acquired. Furthermore, instead of increasing the number of carbon atoms contained in the hydrocarbon group, the number of carbon atoms contained in the obtained film can be reduced by substituting hydrogen for the hydrocarbon group.

From the above, when the raw material that can be used as the raw material of the group III element of the group III nitride in the method for manufacturing the light receiving element according to the present invention is exemplified, it is
Examples of the above-mentioned organic compound in which the hydrocarbon groups are directly bonded and the number of carbon atoms contained in at least one of the hydrocarbon groups is 2 or more are 2 to III group elements.
Compound ((CH ₃ ) ₂ (C ₂ H ₅ ) in which one methyl group and one ethyl group (or propyl group) are directly bonded
Al) or a compound in which three ethyl groups (or propyl groups) are directly bonded to a group III element ((C ₂ H ₅ )
₃ Al etc.) Besides, one hydrogen atom and two hydrocarbon groups (methyl group, ethyl group,
Compounds (H (CH
3) ₂ Al, etc.) or a compound (H (CH ₃ ) (C ₂ H ₅ ) in which one hydrogen atom, one methyl group and one ethyl group (or propyl group) are directly bonded to a group III element.
Al) and a compound (AlH ₃ ) in which three hydrogen atoms are directly bonded to a group III element.

<4> In the above-described embodiment, the description has been given by taking the light receiving element having the PIN diode type device structure as an example. However, in the case of forming another light receiving element such as a PN type, a Schottky type, or a photoconductor. By applying the present invention to the steps of forming the semiconductor layer related to the formation of the respective light receiving regions, the same effect as described above can be obtained.
For example, in the case of a PN diode type, a p-type semiconductor layer and n
Since the depletion region formed at the interface with the type semiconductor layer acts as a light receiving region, both the p-type semiconductor layer and the n-type semiconductor layer are semiconductor layers related to the formation of the light receiving region. It may be formed according to the manufacturing method of the light receiving element according to the present invention. Further, although the case where the contact layer is provided between the semiconductor and the electrode has been described in the present embodiment, the contact layer is not necessarily provided.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a semiconductor growth apparatus.

FIG. 2 is a sectional view of a light receiving element.

FIG. 3 is a graph showing band gap energy of InAlGaN.

FIG. 4 is a graph showing spectra of flame light, sunlight, and room light.

5A is a sectional view of another light receiving element, and FIG.
And (c) are diagrams for explaining the function of the antireflection means.

[Explanation of symbols]

1 Carrier gas tank 2 Oxygen removal device 3 raw material tank 4 Reaction chamber 5 sample holder 6 substrate 7 Raw material tank 10 substrates 11 Low temperature deposition buffer layer 12 Crystal improvement layer 13 Low-temperature deposited intermediate layer 14 n-type semiconductor layer 15 i-type semiconductor layer 16 p-type semiconductor layer 17 p-type contact layer 18 electrodes 19 electrodes 20 Light transmission layer (antireflection means)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Satoshi Ueyama             1-501 Shiogamaguchi, Tenpaku-ku, Nagoya-shi, Aichi             Faculty of Science and Engineering, Jojo University (72) Inventor Hiroshi Amano             1-501 Shiogamaguchi, Tenpaku-ku, Nagoya-shi, Aichi             Faculty of Science and Engineering, Jojo University (72) Inventor Isamu Akasaki             1-501 Shiogamaguchi, Tenpaku-ku, Nagoya-shi, Aichi             Faculty of Science and Engineering, Jojo University F-term (reference) 5F045 AA04 AB09 AB14 AB17 AB18                       AC01 AC07 AC08 AC09 BB12                       CA13                 5F049 MA04 MB07 NA01 NA10 PA04                       PA18 SS01 SZ03

Claims (12)

[Claims] 1. A step of forming a device structure comprising one or a plurality of group III nitride semiconductor layers including a light receiving region on an underlying layer by a metal organic chemical vapor deposition method, at least the light receiving region. In the step of forming a Group III nitride according to the above, at least one of the Group III metal compounds used as a raw material of the Group III element of the Group III nitride is one or more hydrocarbon groups in the Group III element. Is a directly bonded organometallic compound, and the method for producing a light-receiving element, wherein at least one of the hydrocarbon groups has 2 or more carbon atoms. 2. A step of forming a device structure, which comprises one or a plurality of group III nitride semiconductor layers including a light receiving region, on the underlying layer by a vapor phase epitaxy method, and at least forming the light receiving region. In the step of forming a Group III nitride according to the present invention, at least one of the Group III metal compounds used as a raw material for the Group III element of the Group III nitride has one or more hydrogen atoms directly bonded to the Group III element. A method of manufacturing a light receiving element which is a compound obtained by the method. 3. At least one of the group III metal compounds used as a raw material for the group III element of the group III nitride has at least one hydrogen atom and at least one hydrocarbon group in the group III element. The method for producing a light-receiving element according to claim 2, wherein the compound is a compound directly bonded. 4. The method for manufacturing a light-receiving element according to claim 3, wherein at least one of the hydrocarbon groups directly bonded to the group III element has two or more carbon atoms. 5. The light-receiving element according to claim 1, wherein the content of carbon in the group III nitride relating to the formation of the light-receiving region is 1 × 10 ¹⁷ cm ⁻³ or less. Manufacturing method. 6. A method for mitigating lattice mismatch between the device structure and the substrate, comprising one or more semiconductor layers on the substrate, prior to the step of forming the device structure. 6. The method according to claim 1, further comprising a step of forming a base structure by a metal organic chemical vapor deposition method.
A method for manufacturing a light-receiving element according to the item. 7. The method according to claim 1, including a step of forming antireflection means for reducing a reflectance of incident light in the device structure on a light incident surface side of the device structure. Of manufacturing the light receiving element of. 8. The method for manufacturing a light-receiving element according to claim 1, wherein the bandgap energy of the group III nitride for forming the light-receiving region is 3.6 eV or more. 9. The method for producing a light-receiving element according to claim 8, wherein the bandgap energy of the group III nitride for forming the light-receiving region is 4.0 eV or less. 10. The method for producing a light-receiving element according to claim 8, wherein the bandgap energy of the group III nitride for forming the light-receiving region is 4.1 eV or more. 11. The method for manufacturing a light-receiving element according to claim 10, wherein the bandgap energy of the group III nitride for forming the light-receiving region is 4.4 eV or more. 12. A flame sensor manufactured by using the method for manufacturing a light receiving element according to claim 8.