JP2005203605A - Organic metal vapor phase epitaxy method, and nitride-based iii group compound semiconductor light element formed thereby - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nitride-based III group compound semiconductor light-emitting element for emitting ultraviolet rays without using any GaN layers. <P>SOLUTION: The semiconductor light-emitting element 1000 comprises 25nm thick AlGaN buffer layer 101, an n layer 102 made of Al<SB>0.12</SB>Ga<SB>0.88</SB>N, an n cladding layer 103 made of a multiple layer, an emission layer 104 in a single quantum well structure (SQW) by sandwiching a well layer made of non-doped Al<SB>0.005</SB>In<SB>0.045</SB>Ga<SB>0.95</SB>N having approximately 2 nm film thickness with a barrier layer, a block layer 105 made of Al<SB>0.16</SB>Ga<SB>0.84</SB>N, a p cladding layer 106 made of a multiple layer, a p-type contact layer 107 made of GaN, electrodes 110, 120, 140, a protective film 130, and a reflection film 150 on a sapphire substrate 100. Since the AlGaN buffer layer 101 is used, the crystallizability of the n layer 102 made of Al<SB>0.12</SB>Ga<SB>0.88</SB>N is improved, and the crystallizability of a semiconductor layer on the n layer 102 can also be improved. Since no GaN:Si layers are used for an n-side layer, ultraviolet rays generated at the lower portion of the emission layer 104 cannot be absorbed by each layer, are reflected by the reflection film 150, and can be taken out, thus improving the emission efficiency of the ultraviolet light-emitting element. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a metal organic vapor phase epitaxy method for a group III nitride compound semiconductor and a group III nitride compound semiconductor optical device formed thereby. The present invention is particularly effective for a group III nitride compound semiconductor optical device that emits or receives light in the ultraviolet region.

In a group III nitride compound semiconductor light emitting device emitting in the ultraviolet region, a group III nitride compound semiconductor layer having a high aluminum composition is frequently used. The group III nitride compound semiconductor layer having a high aluminum composition is formed based on the following documents.
JP-A-4-321280 JP 2001-028473 A

By the way, when gallium nitride (GaN) is doped with silicon (Si) to form an n-type layer, it absorbs more light in the ultraviolet region. For example, gallium nitride (GaN: Si) doped with silicon (Si) at a concentration of 3 × 10 ¹⁹ / cm ³ has an intensity of about 1 / e ⁴⁰ when UV light having a wavelength of 354.3 nm passes through a thickness of 1 μm. Depressed to. From this, it can be understood that it is not appropriate to use gallium nitride (GaN) for the n-side layer of the group III nitride compound semiconductor light emitting device whose emission wavelength is in the ultraviolet region. Similarly, it is not appropriate to use gallium nitride (GaN) for the p-side layer.

However, in general, the aluminum composition is difficult to control in the epitaxial growth of group III nitride compound semiconductors. In the metal organic chemical vapor deposition method, the ratio of the supply amount of TMA, which is an aluminum raw material, to the amount of TMG, which is a gallium raw material, does not match the composition ratio of an actually formed semiconductor layer, and the composition of one semiconductor wafer is also the same. The difference is big. For example, even if the supply amount of TMA and TMG is 1: 4, the composition of the actually formed semiconductor layer is not Al _0.2 Ga _0.8 N, but Al _0.1 Ga _0.9 N to Al _0.15 Ga _0.85 on one wafer. The composition often varied up to N. Thus, when the aluminum composition exceeds 0.1, it is difficult to control the composition.

  The present invention has been made to solve the above-described problem, and facilitates control of the aluminum composition in a metal-organic vapor phase epitaxy method of a group III nitride compound semiconductor having a high aluminum composition. Objective. Furthermore, it is possible to provide a group III nitride compound semiconductor light emitting device that does not have a layer that absorbs light in the ultraviolet region emitted by the light emitting layer and another layer that absorbs light in the ultraviolet region that should be received by the light receiving layer. It is.

According to the measures of claim 1 for solving the above _{problems, Al x Ga y In 1-} xy N (0 by supplying the group III metal organic compounds containing at least a trimethyl aluminum and trimethyl gallium, and ammonia In the metal organic vapor phase epitaxy method in which <x <1, 0 <y <1) is epitaxially grown, the group III metal organic compound is diffused in the first carrier gas and carried to the epitaxial growth step, and ammonia is the second carrier. It is diffused in the gas and transported to the epitaxial growth process. The epitaxial growth surface area is expressed in units of cm ² , the supply amount of Group III metal organic compound is expressed in p, the unit is μmol / min, and the supply amount of ammonia is expressed in SLM ( Standard Litter per minute) as q, respectively when the r ₁ and r ₂ the flow rate of the first carrier gas and the second carrier gas the unit as a SLM, p / r ₁ is 4 or less or q / ₂ is 0.65 or less, p / q is 40 or less, q / S is equal to or is less than 0.06.

The means described in claim 2 is characterized in that p / q is 8 or less and p / r ₁ is 3.5 or less. The means described in claim 3 is characterized in that p / q is 8 or less and q / r ₂ is 0.5 or less. According to a fourth aspect of the present invention, q / S is 0.25 or more.

The means of claim 5 III nitride compound on a substrate a semiconductor _{Al x Ga y In 1-xy} N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) III nitride compound obtained by laminating in the semiconductor optical element, forming a layer composed of _{Al x Ga y in 1-xy} N of at least one layer by metal organic chemical vapor deposition method according to any one of claims 1 to 4 (0 <x <1) It is characterized by that. Further, according to a sixth aspect of the present invention, the substrate is a sapphire substrate, and a buffer layer made of Al _z Ga _1-z N (0 <z ≦ 1) is previously formed on the sapphire substrate and then epitaxially grown. The buffer layer made of Al _z Ga _1-z N (0 <z ≦ 1) is characterized in that the sapphire substrate is formed at 450 to 600 ° C.

A unit according to claim 7, III-group on the substrate a nitride-based compound semiconductor _{Al x Ga y In 1-xy} N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) III nitride obtained by laminating At least one step of forming a layer made of gallium nitride by metal organic vapor phase epitaxy and a step of forming a layer of aluminum gallium nitride by metal organic vapor phase epitaxy And having the first group III metal organic compound dispersed in the step of forming the layer of aluminum gallium nitride rather than the first carrier gas in which the group III metal organic compound of the step of forming the layer of gallium nitride is dispersed. The carrier gas has a higher flow rate and / or is formed of aluminum gallium nitride than the second carrier gas in which ammonia is dispersed in the step of forming a layer of gallium nitride. Towards the second carrier gas flow rate is large to disperse the ammonia in the step of forming the layer, characterized in that.

  The means according to claim 8 is a group III metal in the step of forming a layer made of aluminum gallium nitride rather than the first carrier gas in which the group III metal organic compound is dispersed in the step of forming the layer made of gallium nitride. The first carrier gas in which the organic compound is dispersed is characterized by being 1.5 times or more larger in flow rate. Furthermore, the means according to claim 9 is characterized in that the second carrier for dispersing ammonia in the step of forming the layer made of aluminum gallium nitride rather than the second carrier gas for dispersing ammonia in the step of forming the layer made of gallium nitride. The gas is characterized by a flow rate that is 2.0 times greater.

  As shown below, the inventor does not simply reduce the supply amount of ammonia, but increases the amount of the carrier gas while maintaining the supply amount, and reduces the concentration of the raw material gas, thereby reducing the concentration of the source group III. It has been found that it is possible to easily control the aluminum composition in the metal-organic vapor phase epitaxy of nitride compound semiconductors. At this time, the variation in composition within the wafer could be reduced. Also, by using a buffer layer formed at a relatively low temperature on a sapphire substrate, it is possible to reduce pits when forming a group III nitride compound semiconductor with a high aluminum composition on the layer above it. became.

The area of the epitaxial growth surface means the total area of one side of the wafer when using the entire surface of one side of one wafer, and the total area of the wafers when using a plurality of wafers. Assuming that the area of the epitaxial growth surface is S and the unit is cm ² , S = 20 for a wafer having a diameter of about 5 cm. When the supply amount of the group III metal organic compound is p with the unit of μmol / min, p can be set to 5 to 200, for example. If the supply amount of ammonia is q with the unit being SLM (Standard Litter per minute), for example, q can be 1-30. If the flow rates of the first carrier gas and the second carrier gas are r ₁ and r ₂ , respectively, where the unit is SLM, r ₁ and r ₂ can each be 1-30.

  At this time, p / q is preferably 40 or less. The amount q of ammonia is preferably large excess. p / q of 40 or less means that the V / III ratio is 1116 or more. p / q of 8 or less means that the V / III ratio is 5580 or more. If p / q is less than 1, a large amount of ammonia is consumed, which is not preferable.

When p / r ₁ is set to 4 or less, further 3.5 or less, or q / r ₂ is set to 0.65 or less and further 0.5 or less, the wafer is sprayed onto the wafer at a low concentration at a high speed, so that variations in composition depending on the position of the wafer can be obtained. In addition to preventing it, the Al composition could be made sufficiently high. This is because unwanted gas phase reactions can be suppressed. Incidentally, when p / r ₁ or q / r ₂ is less than 0.01, the reaction rate becomes very slow, which is not preferable. By setting q / S to 0.06 or more, and further to 0.25 or more, it is possible to grow a group III nitride compound semiconductor having a high aluminum composition while suppressing variation in aluminum composition without impairing the epitaxial growth rate. When q / S exceeds 10, a large amount of ammonia is consumed, which is not preferable.

  The low-temperature buffer layer is preferably formed so that the supply amount of TMA is 1/10 to 1/3 of the supply amount of TMG and the aluminum composition z is 0.05 to 0.2.

If the manufacturing process includes a process for manufacturing GaN and a process for manufacturing AlGaN (which is a pure ternary system in which aluminum and gallium are included in the composition), the Group III raw material in the process of manufacturing GaN The first carrier gas and / or NH ₃ for dispersing the group III raw material in the step of manufacturing AlGaN with respect to the flow rate of the first carrier gas for dispersing NH ₃ and the flow rate of the second carrier gas for dispersing NH ₃ The flow rate of the second carrier gas to be dispersed is increased. This is to manufacture AlGaN under conditions that are partly different from the conditions that are optimal in the process of manufacturing GaN. At this time, the first carrier gas is set to be 1.2 times or more, more preferably 1.5 times or more the flow rate in the process of manufacturing GaN in the process of manufacturing AlGaN. The second carrier gas is set to 1.5 times or more, more preferably 2.0 times or more of the flow rate in the process of manufacturing GaN in the process of manufacturing AlGaN. In any case, it is not preferable to increase it to 5 times or more, because the crystallinity of the AlGaN film is deteriorated regardless of which manufacturing apparatus is used.

  The group III nitride compound semiconductor optical device according to the present invention can have any configuration other than the limitation related to the main configuration of the present invention. The optical element may be a light emitting diode (LED), a laser diode (LD), a photodiode, a photocoupler, or any other optical element. In particular, any manufacturing method can be used as a manufacturing method of the group III nitride compound semiconductor optical device according to the present invention.

  Specifically, sapphire, spinel, Si, SiC, ZnO, MgO, a group III nitride compound single crystal, or the like can be used as a substrate for crystal growth. As a method for crystal growth of the group III nitride compound semiconductor layer, metal organic vapor phase epitaxy (MOVPE) is preferable, but molecular beam vapor phase epitaxy (MBE) and hydride vapor phase epitaxy (HVPE) are used. Also good.

Electrode forming layer other Group III nitride semiconductor layer is expressed by at least _{Al x Ga y In 1-xy} N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) 2 A group III nitride compound semiconductor made of a ternary, ternary, or quaternary semiconductor can be used. Some of these group III elements may be replaced by boron (B) and thallium (Tl), and part of nitrogen (N) may be phosphorus (P), arsenic (As), antimony (Sb ) Or bismuth (Bi).

  Further, when an n-type group III nitride compound semiconductor layer is formed using these semiconductors, Si, Ge, Se, Te, C, etc. are added as n-type impurities, and p-type impurities are used as p-type impurities. Zn, Mg, Be, Ca, Sr, Ba and the like can be added.

  By the above means of the present invention, the above-mentioned problem can be effectively or rationally solved.

In this example, the conditions of the metal organic chemical vapor deposition method for forming a group III nitride compound semiconductor having a high aluminum composition were examined. First, a 1 μm-thick GaN layer was formed on an approximately 25 nm-thick AlN buffer layer made of aluminum nitride (AlN) on a sapphire substrate having a 5 cm diameter (area S = 20) main surface as a C-plane. At this time, the temperature of the sapphire substrate is set to 1075 ° C., and TMG is dispersed and supplied at 40 μmol / min in the first carrier gas 10 SLM, and NH ₃ is dispersed at 10 SLM in the second carrier gas 10 SLM. Supplied.

Next, while maintaining the temperature of the sapphire substrate at 1075 ° C., TMG is 40 μmol / min, TMA is 10 μmol / min, 50 μmol / min (p = 50), and TMG and TMA are dispersed as shown in FIG. flow rate 1 of the carrier gas (r _1), the flow rate of NH ₃ (q), by changing the flow rate of the second carrier gas to disperse NH ₃ (r _2), to produce nine samples. The thickness of the AlGaN layer was about 3 μm.

  The “Al composition (%) by XRD at the position from the center” in FIG. 1 is the “composition” calculated as the XRD spectrum changes linearly with respect to the Al composition (%), and shows an absolute value. is not.

Samples 1, 2, and 3 in FIG. 1 are obtained by changing only the flow rate (r ₁ ) of the first carrier gas for dispersing TMG and TMA. FIG. 2 shows the relationship between the flow rate r ₁ of the first carrier gas and the Al composition (%) for Samples 1, 2, and 3. As the flow rate r ₁ of the first carrier gas increases to ₁₀ , 12.7, and 15.4 SLM, the Al composition increases at the wafer center and at 15 mm from the center, and the difference between them increases. Therefore, by increasing the flow rate of the carrier gas while keeping the same supply amount p of the group III material, that is, by reducing the concentration of the group III material in the carrier gas, the aluminum composition is increased and the position of the wafer is increased. It was found that the variation in aluminum composition due to was reduced.

Samples 1, 4 and 5 in FIG. 1 are obtained by changing only the flow rate (r ₂ ) of the second carrier gas in which NH ₃ is dispersed. FIG. 3 shows the relationship between the flow rate r ₂ of the second carrier gas and the Al composition (%) for Samples 1, 4, and 5. As the flow rate r ₂ of the second carrier gas is increased to 10, 15.6, and 21.1 SLM, the Al composition increases at the wafer center and 15 mm from the center, and the difference therebetween decreases. Therefore, by increasing the flow rate of the carrier gas while keeping the same NH ₃ supply amount q, that is, by reducing the concentration of NH _{3 in} the carrier gas, the aluminum composition increases, and the aluminum depending on the position of the wafer. It was found that the composition variation was reduced.

By the way, this is not the case when the supply amount of NH ₃ itself is reduced. Samples 1, 7, 8, and 9 in FIG. 1 are obtained by changing the NH ₃ supply amount q itself and replenishing the shortage with the flow rate r ₂ of the second carrier gas that disperses NH ₃ . q + r ₂ is constant at 20 (unit is SLM). FIG. 4 shows the relationship between NH ₃ supply amount q and Al composition (%) for Samples 1, 7, 8, and 9. As the NH ₃ supply q decreases to 10, 5, 2.5, and 1.25 SLM, the Al composition increases at both the wafer center and 15 mm from the center, but the difference between them does not decrease. For this reason, if the NH ₃ supply amount q itself is changed, that is, the concentration of NH _{3 in} the carrier gas is reduced, the aluminum composition increases, but the aluminum composition variation due to the wafer position cannot be reduced. I understood.

Figure 5, for example 1 to 6 of FIG. 1, and the flow rate r ₂ of the second carrier gas to disperse the flow r ₁ and NH ₃ of the first carrier gas to disperse the TMG and TMA, "the composition of FIG. 1 It is the graph which showed the relationship with "difference (%)". The composition difference (%) is the difference between the Al composition (%) at 15 mm from the wafer center and the Al composition (%) at the wafer center (0 mm). In FIG. 5, the composition difference (%) is indicated by the size of a circle. As shown in FIG. 5, by changing the flow rate (r ₁ , r ₂ ) of the carrier gas for dispersing them without changing the supply amounts (p and q) of TMG, TMA, and NH ₃ , Variations in the aluminum composition can be suppressed.

In this example, in order to form a group III nitride compound semiconductor having a high aluminum composition, the formation conditions of AlGaN formed as a buffer layer were examined. First, an AlGaN buffer layer having a thickness of about 25 nm was formed on a sapphire substrate having a C-plane main surface with a diameter of 5 cm (area S = 20). At this time, the case where the substrate temperature was 500 ° C. and the case where the substrate temperature was 750 ° C. was examined. When the substrate temperature was 500 ° C., the surface of the AlGaN buffer layer was flat, but when the substrate temperature was 750 ° C., there were many irregularities. On top of this, the temperature of the sapphire substrate is 1075 ° C., TMG is dispersed at 40 μmol / min and TMA is dispersed at 10 μmol / min in the first carrier gas 10 SLM, and NH ₃ is 10 SLM in the second carrier gas 10 SLM. And dispersed and supplied. Thus, an AlGaN layer was formed by epitaxial growth to a thickness of 1 μm, and the pits on the surface were calculated. The AlGaN formed on the AlGaN buffer layer formed at 500 ° C. had a density of about 10 ⁹ / cm ² , but the AlGaN formed on the AlGaN buffer layer formed at 750 ° C. had a density of 10 ¹⁰ / cm ² or more.

FIG. 6 is a cross-sectional view of a group III nitride compound semiconductor optical device (LED) 1000 according to a specific embodiment of the present invention. In the semiconductor optical device (LED) 1000, as shown in FIG. 6, an AlGaN buffer layer 101 having a film thickness of about 25 nm is formed on a sapphire substrate 100 having a thickness of about 100 μm, and silicon (Si) is formed thereon. An n-type AlGaN layer (n-type contact layer) 102 having a thickness of about 1.5 μm made of Al _0.12 Ga _0.88 N having an electron concentration of 5 × 10 ¹⁸ / cm ³ is formed by doping.

On this n-type contact layer 102, a layer 1031 made of Al _0.15 Ga _0.85 N having a thickness of about 1.5 nm and a layer 1032 made of Al _0.04 Ga _0.96 N having a thickness of about 1.5 nm were laminated in 38 cycles. Then, an n-cladding layer 103 composed of multiple layers having a total film thickness of about 100 nm is formed by doping silicon (Si) to an electron concentration of 5 × 10 ¹⁹ / cm ³ .

A light emitting layer 104 having a single quantum well structure (SQW) is formed on the n-clad layer 103. The light emitting layer 104 having a single quantum well structure (SQW) includes a barrier layer 1041 made of non-doped Al _0.13 Ga _0.87 N having a thickness of about 25 nm and a well made of non-doped Al _0.005 In _0.045 Ga _0.95 N having a thickness of about 2 nm. The layer 1042 and a barrier layer 1043 made of non-doped Al _0.13 Ga _0.87 N having a thickness of about 15 nm are stacked.

On the light emitting layer 104 having a single quantum well structure (SQW), a block layer having a thickness of about 40 nm made of Al _0.16 Ga _0.84 N doped with magnesium (Mg) to have a hole concentration of 5 × 10 ¹⁷ / cm ³ 105 is formed. On the block layer 105, a layer 1061 made of Al _0.12 Ga _0.88 N with a film thickness of about 1.5 nm and a layer 1062 made of Al _0.03 Ga _0.97 N with a film thickness of about 1.5 nm were laminated for 30 periods, and magnesium (Mg) A p-cladding layer 106 composed of multiple layers having a total film thickness of about 90 nm is formed to have a hole concentration of 5 × 10 ¹⁷ / cm ³ . On the p-cladding layer 106, a p-type contact layer 107 made of AlGaN having a hole concentration of 1 × 10 ¹⁸ / cm ³ by doping magnesium (Mg) was formed.

  Further, a light-transmitting thin film p-electrode 110 formed by metal vapor deposition is formed on the p-type contact layer 107, and an n-electrode 140 is formed on the n-type contact layer 102. The translucent thin film p-electrode 110 includes a first layer 111 made of cobalt (Co) having a thickness of about 1.5 nm directly bonded to the p-type contact layer 107, and a gold (Au) having a thickness of about 6 nm bonded to the cobalt film. ) And the second layer 112.

  The thick p-electrode 120 includes a first layer 121 made of vanadium (V) having a thickness of about 18 nm, a second layer 122 made of gold (Au) having a thickness of about 15 μm, and aluminum (Al) having a thickness of about 10 nm. The third layer 123 is formed by sequentially laminating the translucent thin film p-electrode 110 from above.

  The n-electrode 140 having a multilayer structure is formed of a first layer 141 made of vanadium (V) having a thickness of about 18 nm and an aluminum (Al) having a thickness of about 100 nm from above a part of the n-type contact layer 102 exposed. It is comprised by laminating | stacking the 2nd layer 142 which consists.

A protective film 130 made of a SiO ₂ film is formed on the top. On the other hand, a reflective metal layer 150 made of aluminum (Al) having a film thickness of about 500 nm is formed by metal vapor deposition on the outermost lower part corresponding to the bottom surface of the sapphire substrate 100. The reflective metal layer 150 may be a metal such as Rh, Ti, or W, or a nitride such as TiN or HfN.

The optical element (LED) 1000 having the above-described configuration was manufactured as follows. The optical element (LED) 1000 was manufactured by metal organic vapor phase epitaxy (hereinafter abbreviated as “MOVPE”). The gases used were ammonia (NH ₃ ), carrier gas (H ₂ and N ₂ ), trimethylgallium (Ga (CH ₃ ) ₃ ) (hereinafter referred to as “TMG”), trimethylaluminum (Al (CH ₃ ) ₃ ) (Hereinafter referred to as “TMA”), trimethylindium (In (CH ₃ ) ₃ ) (hereinafter referred to as “TMI”), silane (SiH ₄ ) and cyclopentadienyl magnesium (Mg (C ₅ H ₅ ) ₂ ) (Hereinafter referred to as “CP ₂ Mg”). The carrier gas used was divided into two systems, group III and NH ₃ , each using 15 SLM. This is an amount larger than 10 SLM for each of the two systems used in the manufacture of elements mainly composed of GaN.

First, a single crystal substrate 100 having a C-plane main surface cleaned by organic cleaning and heat treatment is mounted on a susceptor mounted in a reaction chamber of a MOVPE apparatus. Next, the substrate 100 was baked at a temperature of 1100 ° C. while flowing H ₂ into the reaction chamber at normal pressure.
Next, the temperature of the substrate 100 was kept at 1075 ° C., and H ₂ , NH ₃ , TMG and TMA were supplied to form the AlGaN buffer layer 101 with a film thickness of about 25 nm.

Next, H ₂ , NH ₃ , TMG, TMA, and silane were supplied, and an n-type contact layer 102 made of Al _0.12 Ga _0.88 N having an electron concentration of 5 × 10 ¹⁸ / cm ³ was formed thereon. Thereafter, while controlling the supply amount of H ₂ , NH ₃ , TMG, TMA, and silane, from the layer 1031 made of Al _0.15 Ga _0.85 N having a thickness of about 1.5 nm and the Al _0.04 Ga _0.96 N having a thickness of about 1.5 nm. The n clad layer 103 composed of multiple layers having a total film thickness of about 100 nm was formed by laminating 38 layers of the layer 1032 and doping silicon (Si) to an electron concentration of 5 × 10 ¹⁹ / cm ³ .

Next, the temperature of the substrate 100 is lowered to 825 ° C., and N ₂ or H ₂ , NH ₃ , TMG and TMI are supplied, and the barrier layer 1041 made of non-doped Al _0.13 Ga _0.87 N having a thickness of about 25 nm. And a well layer 1042 made of non-doped Al _0.005 In _0.045 Ga _0.95 N having a thickness of about 2 nm and a barrier layer 1063 made of non-doped Al _0.13 Ga _0.87 N having a thickness of about 15 nm are sequentially stacked to obtain a single quantum well. A light emitting layer 104 having a structure was formed.

Next, the temperature of the substrate 100 is maintained at 1025 ° C., and N ₂ or H ₂ , NH ₃ , TMG, TMA, and CP ₂ Mg are supplied while being controlled, and Al _0.16 Ga _0.84 N doped with magnesium (Mg). Magnesium in which a block layer 105 having a thickness of about 40 nm, a layer 1061 made of Al _0.12 Ga _0.88 N having a thickness of about 1.5 nm, and a layer 1062 made of Al _0.03 Ga _0.97 N having a thickness of about 1.5 nm are laminated 30 times. A p-cladding layer 106 made of a multilayer having a total thickness of about 90 nm doped with (Mg) and a p-type contact layer 107 having a thickness of about 30 nm made of AlGaN doped with magnesium (Mg) were sequentially formed.

Thereafter, the block layer 105, the p-cladding layer 106 and the p-type contact layer 107 which are p-side layers are made p-type, and the hole concentrations are 5 × 10 ¹⁷ / cm ³ , 5 × 10 ¹⁷ / cm ³ and 5 ×, respectively. After forming a p-type layer of 10 ¹⁸ / cm ³ , each electrode (110, 120, 140), protective film 130, and reflective metal layer 150 were formed.

  With the above configuration, light having a wavelength of 350 nm downward from the light emitting layer is not absorbed by the n-type GaN layer, and the light emission intensity is 2 as compared with the case where n-type GaN is used as the n contact layer. Doubled.

  The present invention is suitable for an optical element having a short wavelength in which an emission wavelength exists in the ultraviolet region. Applications of short-wavelength optical elements include photochemistry using a photoexcitation catalyst, illumination used to excite phosphors, bio-related fields such as kidnapping lights, and black lights used in fluorescent lamps. it can.

2 is a table showing the results of Example 1. FIG. The graph which shows the flow rate r1 of _1st carrier gas, and the relationship of Al composition of a semiconductor layer. The graph which shows the relationship between flow volume r2 of _2nd carrier gas, and Al composition of a semiconductor layer. Graph showing the relationship between the Al composition of the flow q and the semiconductor layer of the NH _3. The graph which shows the flow rate r1 of _1st carrier gas, the flow rate r2 of _2nd carrier gas, and the dispersion | variation in Al composition of a semiconductor layer. Sectional drawing of the semiconductor optical element (LED) 1000 which concerns on the Example of this invention.

Explanation of symbols

1000: Semiconductor optical device (LED)
100: Sapphire substrate 101: AlGaN buffer layer 102: n-type AlGaN layer 103: n clad layer (multilayer)
104: Single quantum well light emitting layer (SQW)
105: Block layer 106: p-clad layer (multilayer)
107: p-type contact layer 110: translucent thin film p-electrode 120: p-electrode 130: protective film 140: n-electrode 150: reflective metal layer

Claims (9)

A group III metal organic compounds containing at least a trimethyl aluminum and trimethyl _{gallium, Al x Ga y In 1-} xy N by supplying ammonia (0 <x <1, 0 <y <1) and the organic metal vapor phase epitaxial growth In the growth method,
The Group III metal organic compound is diffused in the first carrier gas and carried to the epitaxial growth process,
Ammonia is diffused into the second carrier gas and carried to the epitaxial growth process,
The area of the epitaxial growth surface is S with the unit of cm ² , the supply amount of the group III metal organic compound is p with the unit of μmol / min, the supply amount of ammonia is q with the unit of SLM (Standard Litter per minute) as q, the first When the flow rates of the carrier gas and the second carrier gas are S ₁ and r ₁ and r ₂ respectively,
p / r ₁ is 4 or less or q / r ₂ is 0.65 or less,
p / q is 40 or less,
An organometallic vapor phase growth method characterized in that q / S is 0.06 or more. p / q is 8 or less,
metal organic chemical vapor deposition method according to claim 1, wherein the p / r ₁ is 3.5 or less. p / q is 8 or less,
_{2. The} metal organic chemical vapor deposition method according to claim 1, wherein q / r ₂ is 0.5 or less. The metalorganic vapor phase epitaxy according to any one of claims 1 to 3, wherein q / S is 0.25 or more. Group III nitride compound on a substrate in a semiconductor _{Al x Ga y In 1-xy} N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) was laminated III nitride compound semiconductor optical device,
5. A layer comprising at least one layer of Al _x Ga _y In _1-xy N (0 <x <1) is formed by metal organic vapor phase epitaxy according to claim 1. Group III nitride compound semiconductor optical device. The substrate is a sapphire substrate;
The sapphire substrate is epitaxially grown after a buffer layer made of Al _z Ga _1-z N (0 <z ≦ 1) is formed in advance,
6. The group III nitride compound semiconductor light according to claim 5, wherein the buffer layer made of Al _z Ga _1-z N (0 <z ≦ 1) is formed at a sapphire substrate of 450 to 600 ° C. element. In the manufacturing method of a group III nitride compound semiconductor _{Al x Ga y In 1-xy} N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) was laminated III nitride compound semiconductor optical device on a substrate,
At least one step of forming a layer made of gallium nitride by metal organic vapor phase epitaxy and a step of forming a layer of aluminum gallium nitride by metal organic vapor phase epitaxy,
The first carrier gas for dispersing the group III metal organic compound in the step of forming the layer made of aluminum gallium nitride rather than the first carrier gas for dispersing the group III metal organic compound in the step of forming the layer made of gallium nitride. The flow rate is larger,
And / or the second carrier gas for dispersing ammonia in the step of forming the layer made of aluminum gallium nitride has a larger flow rate than the second carrier gas for dispersing the ammonia in the step of forming the layer made of gallium nitride. ,
A method for producing a group III nitride compound semiconductor optical device. The first carrier gas for dispersing the group III metal organic compound in the step of forming the layer made of aluminum gallium nitride rather than the first carrier gas for dispersing the group III metal organic compound in the step of forming the layer made of gallium nitride. 8. The method for producing a group III nitride compound semiconductor optical device according to claim 7, wherein the flow rate is 1.5 times or more larger. The flow rate of the second carrier gas for dispersing ammonia in the step of forming the layer made of aluminum gallium nitride is 2.0 times or more larger than the second carrier gas for dispersing ammonia in the step of forming the layer made of gallium nitride. The method for producing a group III nitride compound semiconductor optical device according to claim 7.

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