JPH104246A - Semiconductor light emitting diode and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light emitting diode having semiinsulating current constricting layer made of III-V nitride. SOLUTION: A III-V nitride 105 is grown using an SiNx film as a selective growing mask while doping the nitride 105 so as to contain carbon atoms in the concentration exceeding 10<17> /cm<3> . The formed nitride layer 105 becoming a semiinsulating layer can be used as a clad layer of a current constricting layer and a light guide path. In such a constitution, the semi-insulating layer of a specific shape can be grown thereby enabling a high performance light emitting diode to be formed. Furthermore, the III-V nitride layer is to be grown by gas MBE process using a compound having alkyl radical for either a group III material or a group V material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a structure of a semiconductor light emitting device having a semiconductor layer made of a III-V nitride compound, and a method of manufacturing the same.

[0002]

2. Description of the Related Art A light emitting device having a current confinement structure and using a III-V nitride layer has attracted attention. Referring to FIG. 9, a current confinement structure of a conventional III-V nitride-based light emitting device is described with reference to an InGaN / GaN light emitting diode (L).
ED) will be described as an example.

On a sapphire substrate 21, MOVPE
GaN buffer layer 2 by (organic metal vapor phase epitaxy) method
2, n-GaN cladding layer 23, InGaN active layer 24,
A p-GaN cladding layer 25 and a p-InGaN contact layer 26 are sequentially grown and formed. Since the sapphire substrate 21 has no conductivity, the P-InGaN contact layer 26, the p-GaN cladding layer 25, the InGaN active layer 24, and the n-GaN cladding layer 23 are partially etched to form an n-GaN cladding layer. A part of the layer 23 is exposed. A dielectric thin film 29 is formed on the p-InGaN contact layer 26 and the exposed n-GaN cladding layer 23. An opening for contact is formed in the dielectric thin film 29, and a p-side electrode 28 and an n-side electrode 27 that are in contact with the p-InGaN contact layer 26 and the n-GaN cladding layer 23 through the opening, respectively. 29. An electrode close to the InGaN active layer 24 (in this example, the p-side electrode 28) has a stripe shape for supplying a current to a stripe region to emit light, and is generally called a stripe electrode because of this structure.

[0004]

In order to improve the efficiency of a light emitting device, a structure in which a current confinement layer is provided near an active layer, a light confinement structure in which light is confined in a direction parallel to a substrate surface (light confinement structure), and the like. Layer) is known to be effective. Such a current confinement layer and a light confinement layer have been put into practical use as a buried hetero (BH) structure in a light emitting element in the near infrared region using a GaAs or InP-based compound semiconductor. On the other hand, in III-V nitride, such BH
An element having a structure is not yet known.

The inability to fabricate the BH structure includes the following factors. That is, an etching method necessary for forming a current confinement layer or a light confinement layer is not known. For example, an etching method using plasma is currently in a research stage, and an effective method as a wet etching method is known. It is conceivable to use a semi-insulating semiconductor to produce a current confinement structure or an optical waveguide structure. However, in the case of a III-V nitride, a thermally stable III-V nitride film is used. For example, in a crystal growth method using a chloride VPE method, a semi-insulating Ga is added by adding Zn.
Although it is known that N can grow, this GaN
The film is thermally unstable, and changes to a p-type conductive film by heat treatment.

SUMMARY OF THE INVENTION An object of the present invention is to provide a light emitting device having a III-V nitride layer having a current confinement structure or an optical waveguide structure without etching a III-V nitride, and its manufacture. An object of the present invention is to provide a light emitting device which has excellent luminous efficiency and is coupled to other optical systems with high efficiency.

[0007]

In order to achieve the above object, a semiconductor optical device according to the present invention comprises a III-V nitride containing at least 10 ¹⁷ carbon atoms / cm ^{3 in} a light emitting device. It is characterized by including at least one layer.

[0008] A method of manufacturing a semiconductor optical device of the present invention, III containing a concentration of 10 ¹⁷ / cm ³ or more carbon atoms
Gas source MB to grow the -V nitride layer
The E method is used. Here, the gas source MBE method is referred to as III.
An MBE method in which at least one of the group-based or group-V-based raw materials is not a metal source.

Preferably, a compound containing an alkyl group is used for at least one of the group III and group V raw materials. For example, it is preferable to use triethyl (or trimethyl) gallium as the group III material and dimethyl (or monomethyl) hydrazine as the group V material.

A III-V nitride containing carbon atoms at a concentration of 10 ¹⁷ atoms / cm ³ or more is a semi-insulating material. This semi-insulating III-V nitride is extremely stable against heat, and does not lose its semi-insulating property even when subjected to a heat treatment in a nitrogen atmosphere at 750 ° C. for about one hour. Therefore, Z
The semi-insulating property of the III-V nitride does not change even in the heat treatment for converting the GaN layer to which n or the like is added to the p-type.

Crystals are grown by gas source MBE using a compound containing an alkyl group in at least one of the group III and group V materials. Thereby, the number of carbon atoms is 10 ¹⁷ / cm
A III-V nitride layer containing at a concentration of ³ or more can be obtained. For example, when an organic metal such as triethyl (or trimethyl) gallium is used as a group III material, selective growth can be particularly easily performed. By employing such a selective growth method, it becomes easy to form a desired III-V nitride layer having a desired function such as current confinement in a desired region.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 (a) to 1 (c) and FIG.
(D) and (e) are perspective views of the semiconductor light emitting device, sequentially showing the steps of actually manufacturing the semiconductor light emitting device of the first embodiment of the present invention. This embodiment example is semi-insulating
This is an example in which the present invention is applied to a light-emitting element having a stripe-electrode structure in which a III-V nitride layer is provided as a current confinement layer. Each of the figures is a perspective view focusing on one element, as in other figures described later. There is.

As a material of the substrate 100, GaP was used. N-GaN serving also as a buffer layer on the semiconductor substrate 100
Clad layer 101, InGaN active layer 102, and p-
The GaN cladding layers 103 were sequentially formed by an epitaxial growth method. Thus, the structure shown in FIG. 1A was obtained. For crystal growth of these layers, a gas source MBE method was used, and Ga, In, and excited nitrogen were used as raw materials. Here, excited ammonia can be used instead of excited nitrogen. As a doping source, Mg is used for p-type,
Si was used for the n-type.

When crystal growth is performed by the gas source MBE method, a semiconductor light emitting device having better characteristics can be obtained without using a compound containing carbon as a raw material, for example, an organic metal such as triethylgallium or dimethylhydrazine. These layers are grown by MOV instead of gas source MBE.
It may be performed by PE (metal organic chemical vapor deposition), chloride VPE, or the like.

Next, a dielectric thin film made of SiN _x was formed on the entire surface of the p-GaN cladding layer 103, followed by patterning by photolithography and chemical etching to form a striped SiN _x film 104.
Thus, the structure shown in FIG. 1B was obtained.

Further, a semi-insulating GaN layer 105 was grown on the P-GaN cladding layer 103 using the striped SiN _x film 104 as a selective growth mask. Semi-insulating GaN
The growth of the layer 105 is performed by using triethyl gallium as a raw material,
Gas source MBE using 1,1-dimethylhydrazine
Performed by the method. Thus, the structure shown in FIG. 1C was obtained. Here, the growth temperature was in the range of 500 to 850 ° C., and a good semi-insulating GaN layer 105 was grown in a region other than the region where the striped SiN _x film 104 was left.

Subsequently, the striped SiN _x film 104 was removed with a hydrofluoric acid solution to obtain a structure shown in FIG. Each epitaxial growth layer shown in FIG.
When the layers are formed by the OVPE method or the chloride VPE method, a heat treatment is subsequently performed to make these layers p-type.

Further, the semiconductor substrate 100 was polished to a thickness of about 100 μm so as to be easily cleaved. Thereafter, a p-side electrode 107 was formed on the front side of the stack, and an n-side electrode 106 was formed on the back side of the substrate. Thus, a final structure shown in FIG. 2E was obtained.

In the first embodiment, the current confinement layer is made of a semi-insulating GaN from the dielectric film 29 in the conventional light emitting device.
Layer 105 has been replaced. Semi-insulating GaN layer 105
Has a thermal expansion coefficient closer to that of the semiconductor material forming the cladding layer and the active layer than the dielectric film 29. Therefore, according to the light emitting device of the present embodiment, the light emission caused by thermal strain It is possible to prevent performance degradation of the element.

FIG. 3 is a perspective view showing the structure of a light emitting device according to a modification of the first embodiment. In this example, a semi-insulating substrate is used as the substrate 200. On a GaAs semi-insulating substrate 200, an n-GaN cladding layer 201, InGaN
An active layer 202 and a p-GaN cladding layer 203 are sequentially grown and formed, a semi-insulating GaN layer 205 serving as a current confinement layer is provided on the p-GaN cladding layer, and the p-side electrode 20 is formed thereon.
7 are formed. On the other hand, the n-side electrode 206 is formed on the exposed n-GaN cladding layer 201 by etching from the surface of the growth layer to the middle of the n-GaN cladding layer 201. The light emitting element of this modification is an example in which a semi-insulating substrate is used as the substrate, and the other configuration except for the electrode structure is the same as that of the first embodiment.

FIGS. 4 (a) to 4 (c) and FIGS. 5 (d) to 5 (d)
(F) is a perspective view of a light emitting element which shows a process of actually manufacturing a light emitting element of a second embodiment example of the present invention in order. This embodiment is an example in which a semi-insulating layer is provided between an active layer and a substrate.

As a material of the substrate 300, a GaP semiconductor was used. An n-GaN buffer layer 301 was grown on the GaP semiconductor substrate 300 to obtain the structure shown in FIG. This growth is achieved by gas source MBE, chloride VPE,
Alternatively, any of the MOVPE methods may be used. However, in the case of using the gas source MBE method, it is better to use gallium and excited nitrogen (or excited ammonia) as raw materials and not to use a carbon compound such as an organic metal or dimethylhydrazine, whereby good emission characteristics can be obtained. .

Next, a dielectric thin film made of SiN _x is formed on the entire surface of the n-GaN buffer layer 301, and is patterned by photolithography and chemical etching to form a striped SiN _x film 302. Thus, the structure shown in FIG. 4B was obtained. The striped SiN _x film 302 may alternatively be formed of a SiO ₂ film.

Using the striped SiN _x film 104 as a selective growth mask, a semi-insulating GaN layer 303 was grown on the n-GaN buffer layer 301. As a result, FIG.
The structure shown in (c) was obtained. The growth of the semi-insulating GaN layer 303 was performed by a gas source MBE method using triethylgallium and 1,1-dimethylhydrazine as raw materials. At a growth temperature of range of 500-850 ℃, stripe the SiN _x film 3 good semi-insulating GaN layer 303
02 was formed in a region other than the region in which 02 was left.

Subsequently, the striped SiN _x film 302 was removed with a hydrofluoric acid solution to obtain a structure shown in FIG. Further, n-Ga exposed in a stripe shape from above the semi-insulating GaN layer 303 and between the semi-insulating GaN layers 303.
An n-GaN clad layer 304, an InGaN active layer 305, and a p-GaN
A cladding layer 306 was grown and formed sequentially. This allows
The structure shown in FIG. 5E was obtained. Gas source MBE was used for crystal growth of these layers, and Ga, In, and excited nitrogen were used as raw materials. Excited ammonia may be used instead of excited nitrogen. As a doping source, Mg is used for p-type,
Si was used for the n-type. This step itself is performed by MOVPE or chloride VPE instead of gas source MBE.
Method may be used.

The substrate 300 was polished so as to have a thickness of about 100 μm, which was easily cleaved. Thereafter, a p-side electrode was formed on the front side of the growth layer and an n-side electrode was formed on the back side of the substrate 300, respectively, to obtain a final structure shown in FIG.

In the structure of the second embodiment, the electrodes can be made farther from the active layer than in the structure of the first embodiment. By moving the electrode away from the active layer, penetration of the electrode material into the active layer and light absorption by the electrode layer are reduced, and improvement in characteristics of the light emitting element can be expected. Further, since the active layer and the semi-insulating layer can be brought close to each other, it is effective in confining light.

FIGS. 6 (a) to 6 (c) and FIGS. 7 (d) to 7 (d)
(F), FIGS. 8 (g) and (h) sequentially show the steps of actually manufacturing the light emitting device of the third embodiment of the present invention.
It is a perspective view. In this embodiment, the embedded heterostructure (B
This is an example in which the present invention is applied to a light emitting element having a H) structure.

As a material of the substrate 400, a GaP semiconductor was used. An n-GaN buffer layer 401 was grown and formed on the GaP semiconductor substrate 400 to obtain the structure shown in FIG. This step itself is performed by gas source MBE, chloride VPE
Method or MOVPE method. However, when the gas source MBE method is used, better characteristics can be obtained by using Ga and excited nitrogen or excited ammonia as raw materials and not using an organic metal or a carbon compound such as dimethylhydrazine.

Next, a dielectric thin film made of SiN _x is formed on the entire surface of the n-GaN buffer layer 401 and is etched by photolithography and chemical etching to form a SiN _x film 402 having a stripe-shaped opening. The structure shown in FIG. 6B was obtained.

An SiN _x film 40 having a stripe-shaped opening
2 is used as a mask to perform selective growth, and the n-GaN cladding layer 40 is sequentially formed on the n-GaN buffer layer 401.
3. An InGaN active layer 404 and a p-GaN cladding layer 405 were grown. As a result, as shown in FIG.
A striped semiconductor laminated structure was obtained. A gas source MBE method was used for crystal growth of these laminates. G as raw material
a, In, and excited nitrogen were used. Excited ammonia may be used instead of excited nitrogen. Further, S used as a mask
In order to suppress the deposition on the iN _x film 402, a growth temperature several degrees higher than that of the Ga Knudsen cell was adopted. As a doping source, Mg is used for p-type and Si is used for n-type.
Was used respectively.

Next, the SiN _x film 402 was removed with a hydrofluoric acid solution to obtain a structure shown in FIG. Then, n-
A dielectric thin film made of SiN _x is formed on the entire surface including the stacked structure of the GaN buffer layer 401 and the stripe structure, and this is patterned by photolithography and chemical etching, and a stripe-shaped SiN _{x is} formed only on the p-GaN clad layer 405. The structure shown in FIG. 7E was obtained except for the film 406.

Further, a semi-insulating GaN layer 407 for burying the stripe structure was grown on the n-GaN buffer layer 401 and on the entire surface including the side surfaces of the stripe structure, using the stripe-shaped SiN _x film 406 as a selective growth mask. Thus, the structure shown in FIG. 7F was obtained. Semi-insulating Ga
The growth of the N layer 407 is performed by using triethyl gallium as a raw material,
Gas source MBE using 1,1-dimethylhydrazine
Performed by the method. With the growth temperature in the range of 500-850 ° C., a good semi-insulating GaN layer 407 was formed in a region other than the region where the striped SiN _x film 406 was left.

A striped SiN _x film 4 made of a hydrofluoric acid solution
06 was removed to obtain a structure shown in FIG. Subsequently, the substrate 400 is polished so as to have a thickness of about 100 μm, which is easily cleaved.
The n-side electrodes 106 were formed on the back surface of the substrate 400, respectively, to finally obtain the structure shown in FIG.

In the third embodiment, since the semi-insulating GaN layer 407 functions not only as a current confinement layer but also as a cladding layer of an optical waveguide, light is emitted with a smaller current than in the first and second embodiments. It becomes possible to do. In addition, since the field distribution of the emitted light is easily controlled, the light emitting element can be optically coupled to another optical element with high coupling efficiency.

In each of the above embodiments, an example in which GaP is used as a base (substrate) for growing a semi-insulating film has been described. However, another III-V compound semiconductor can be used as a base. is there. Also, SiC, Si, or G
Almost the same characteristics can be obtained by using a group IV semiconductor such as e or an oxide crystal such as sapphire or spinel as a substrate. Among them, when a crystal having a diamond structure or a zinc blend structure is used as a base, and a III-V nitride semi-insulating film is grown on a surface on which the zinc blend structure is easily grown, for example, a (100) plane, A high-quality semi-insulating film can be obtained.

In each of the first to third embodiments, an example is shown in which a substrate having n-type conductivity is used. However, instead of this, a p-type substrate or a modification of the first embodiment is used. Similar characteristics can be obtained by using a semi-insulating substrate. That is, the conductivity of the III-V nitride in the layer in contact with the semi-insulating GaN layer may be p-type or n-type.

Here, when a substrate other than the n-type is used, the order of lamination of the cladding layers and the electrode configuration are changed from those of the above embodiment. Taking the case of Embodiment 1 as an example, when a p-type substrate is used as the substrate 100, the n-GaN cladding layer 101 is a p-GaN cladding layer, and the p-GaN cladding layer 103 is an n-GaN cladding layer. In addition, a p-side electrode is formed on the back surface of the substrate, and an n-side electrode is formed on the upper surface of the growth layer.

When a semi-insulating substrate is used,
Since no electrode can be formed on the back side of the semi-insulating substrate, FIG.
The structure is as shown in FIG. In this case, contrary to FIG.
The side closer to the substrate may be p-type conductive and the side farther from the substrate may be n-type conductive.

[0040] In the above respective embodiments, an example employing the GaN as the material of the semi-insulating layer, In addition, an In _{x
Ga y Al z N (x +} y + z = 1) may be employed quaternary compounds such as, further, V group elements constituting the quaternary compound, there in place of the N B, As, P-like You may.

The semiconductor layer in contact with the semi-insulating layer also
Not only _{GaN, In x Ga y Al z} N (x + y + z = 1) may be employed quaternary compounds such as, furthermore, V group elements constituting the quaternary compound, in place of N B, As, P or the like may be used.

In the above-described embodiment, an example in which triethylgallium and 1,1-dimethylhydrazine are used as raw materials in the gas source MBE method for obtaining a semi-insulating layer has been described. However, when the gas source MBE method is adopted, a good semi-insulating layer can be obtained even if at least one of the group III and group V materials is a material containing a carbon compound.

Group III raw materials for obtaining the semi-insulating layer are aluminum, trimethylaluminum, triethylaluminum, dimethylaluminum hydride, indium, trimethylindium, triethylindium, ethyldimethylindium gallium, triethylgallium, and trimethylgallium.

The nitrogen raw materials are 1,1-dimethylhydrazine, 1,2-dimethylhydrazine, monomethylhydrazine, excited nitrogen and excited ammonia.

When aluminum or indium is used as the group III raw material, it was effective to raise the growth temperature in order to suppress the deposition of a semi-insulating film on the SiN _x film. The standard of the growth temperature is several degrees higher than the temperature of the raw material Knudsen cell.

[0046]

According to the semiconductor light emitting device of the present invention, the III-V nitride layer containing carbon atoms at a concentration of 10 ¹⁷ / cm ³ or more becomes semi-insulating, and has a semi-insulating property stable to heat. Since it is a film, a semi-insulating film having a desired shape can be formed without requiring an etching step by photolithography or the like. Therefore, the present invention has a remarkable effect of facilitating the manufacture of a semiconductor light emitting device having a III-V nitride layer having a current confinement structure or a III-V nitride layer having an optical waveguide structure based on a difference in refractive index. To play.

[Brief description of the drawings]

FIGS. 1A to 1C are perspective views of a light emitting device in each process step of manufacturing a light emitting device according to a first embodiment of the present invention.

FIGS. 2D and 2E are FIGS. 1A to 1C, respectively.
FIG. 3 is a perspective view of a light emitting element for each process step following FIG.

FIG. 3 is a sectional view of a modification of the light emitting device of the first embodiment.

FIGS. 4A to 4C are perspective views of a light emitting device in each process step of manufacturing a light emitting device according to a second embodiment of the present invention.

FIGS. 5 (d) to 5 (f) are perspective views of the light emitting element in each process step following FIGS. 4 (a) to 4 (c), respectively.

FIGS. 6A to 6C are perspective views of a light emitting element in each process step of manufacturing a light emitting element according to a third embodiment of the present invention.

FIGS. 7 (d) to (f) are perspective views of the light emitting element in each process step following FIGS. 6 (a) to (c), respectively.

8 (g) to 8 (h) are perspective views of the light emitting element in each process step following FIGS. 7 (d) to 7 (f).

FIG. 9 is a sectional view of a conventional semiconductor light emitting device.

[Explanation of symbols]

Reference Signs List 100 GaP semiconductor substrate 101 n-GaN cladding layer 102 InGaN active layer 103 p-GaN cladding layer 104 SiN _x film 105 semi-insulating GaN layer 106 n-side electrode 107 p-side electrode 200 GaP semi-insulating substrate 201 n-GaN cladding layer 202 InGaN active layer 203 p-GaN cladding layer 205 semi-insulating GaN layer 206 n-side electrode 207 p-side electrode 300 GaP semiconductor substrate 301 n-GaN buffer layer 302 SiN _x film 303 semi-insulating GaN layer 304 n-GaN cladding layer 305 InGaN active layer 306 p-GaN cladding layer 307 n-side electrode 308 p-side electrode 400 GaP semiconductor substrate 401 n-GaN buffer layer 402 SiN _x film 403 n-GaN cladding layer 404 InGaN active layer 405 p-GaN cladding layer 406 stripe Jo the SiN _x film 4 7 Semi-insulating GaN layer 408 n-side electrode 409 p-side electrode 21 sapphire substrate 22 GaN buffer layer 23 n-GaN cladding layer 24 InGaN active layer 25 p-GaN cladding layer 26 p-InGaN contact layer 27 n-side electrode 28 p side Electrode 29 Dielectric film

Claims (5)

[Claims] 1. A semiconductor light emitting device comprising a semi-insulating layer constituted as a III-V nitride compound and containing carbon atoms at a concentration of 10 ¹⁷ cm ⁻³ or more. 2. The method according to claim 2, wherein the III-V nitride compound is Ga
N, InGaAlN, InGaAlB, InGaAlAs, and
2. The semiconductor light emitting device according to claim 1, wherein the compound is one kind of compound selected from the group consisting of InGaAlP. 3. The semiconductor light emitting device according to claim 1, wherein said semi-insulating layer is provided as a current confinement layer. 4. The semiconductor light emitting device according to claim 1, wherein said semi-insulating layer is provided as a cladding layer of an optical waveguide. 5. The method for manufacturing a semiconductor light emitting device according to claim 1, wherein the semi-insulating layer includes an alkyl group in at least one of the group III and group V raw materials. An element manufacturing method characterized by being grown by a gas source MBE method using a raw material.