JP2005051170A - Group iii nitride compound semiconductor light emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve electrostatic withstand voltage without lowering light emission property of a group III nitride compound semiconductor light emitting element. <P>SOLUTION: An n side multilayer (electrostatic withstand voltage improvement layer) 105 wherein five pairs of a 3 nm-thick layer 1051 consisting of nondoped In<SB>0.03</SB>Ga<SB>0.97</SB>N and a 20 nm-thick layer 1052 consisting of nondoped GaN are laminated is formed in a negative electrode side of a light emitting layer 106 of a multilayer quantum well structure wherein three pairs of a 3 nm-thick well layer 1061 consisting of nondoped In<SB>0.2</SB>Ga<SB>0.8</SB>N and a 20 nm-thick barrier layer 1062 consisting of nondoped GaN are laminated. In a positive electrode side of the light emitting layer 106, a p side multilayer (electrostatic withstand voltage improvement layer) 108 wherein a 3 nm-thick layer 1081 consisting of nondoped In<SB>0.03</SB>Ga<SB>0.97</SB>N and a 20 nm-thick layer 1082 consisting of nondoped GaN are laminated is formed. The n side multilayer 105 and the p side multilayer 108 allow an applied voltage to extend in a wide range of an n electrode side and a p electrode side of a light emitting layer without concentrating on a part of the n electrode side and the p electrode side of the light emitting layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a group III nitride compound semiconductor light emitting device. The present invention provides a group III nitride compound semiconductor light emitting device structure having a high electrostatic withstand voltage.

Although group III nitride compound semiconductor light emitting devices are being widely used as light emitting devices in the green, blue to ultraviolet region, there are still room for improvement in various characteristics of group III nitride compound semiconductor light emitting devices other than the emission intensity. In particular, the electrostatic withstand voltage is much lower than that of gallium / arsenic light emitting elements and indium / phosphorous light emitting elements, and a significant improvement in electrostatic withstand voltage is expected. Here, in order to improve the electrostatic withstand voltage of the group III nitride compound semiconductor light emitting device, the following proposals have been made.
Japanese Patent Laid-Open No. 11-191639 JP 2000-68594 A Japanese Patent Laid-Open No. 2000-244072 JP 2001-203385 A

  Even with these techniques, the electrostatic withstand voltage of the group III nitride compound semiconductor light emitting device is not sufficient, and the electrostatic withstand voltage is in a trade-off relationship with the light emission intensity and the driving voltage.

  Therefore, the present invention has an object to improve the electrostatic withstand voltage without deteriorating the light emission intensity and the driving voltage with respect to the conventional technique.

In order to solve the above-described problem, according to the means of claim 1, in a group III nitride compound semiconductor light emitting device having a light emitting layer having a multiple quantum well structure, a non-doped In region is formed on the n electrode side of the light emitting layer. _x1 Ga _1-x1 N (0 <x1 <1) layer and non-doped GaN layer n-side multiple layers, and non-doped In _x2 Ga _1-x2 N on the p-electrode side of the light emitting layer A III-nitride group having a p-side multiple layer of a layer made of (0 <x2 <1) and a layer made of non-doped GaN, and the well layer of the light emitting layer of the multiple quantum well structure contains at least indium (In) Compound semiconductor Al _y Ga _1-yz In _z N (0 ≦ y <1, 0 <z ≦ 1) and In _x1 Ga _1-x1 N (0 <x1 <1) forming an n-side multilayer The indium (In) composition x1 of the layer and the indium (In) composition _{x2 of} In _x2 Ga _1-x2 N (0 <x2 <1) forming the p-side multilayer are both multiquantum wells. Structure light emitting layer well layer It is a Group III nitride compound semiconductor light-emitting device according to claim less than the composition z of beam (an In).

According to the second aspect of the present invention, the composition x1 of indium (In) in the layer made of non-doped In _x1 Ga _{1 -x1} N (0 <x1 <1) in the n-side multilayer, and the p-side multiple The composition x2 of indium (In) in the layer made of non-doped In _x2 Ga _1-x2 N (0 <x2 <1) in the multilayer is 0.02 or more and 0.07 or less. According to the third aspect of the present invention, the thickness of the n-side multilayer non-doped In _x1 Ga _1-x1 N (0 <x1 <1) and the p-side multilayer non-doped In _x2 The thickness of each layer made of Ga _1-x2 N (0 <x2 <1) is 0.5 nm or more and 6 nm or less.

According to the fourth aspect of the present invention, the thickness of the layer composed of non-doped In _x1 Ga _{1 -x1} N (0 <x1 <1) in the n-side multilayer is relative to the thickness of the well layer of the light emitting layer. And the ratio of the thickness of the p-side multi-layered non-doped In _x2 Ga _1-x2 N (0 <x2 <1) to the thickness of the well layer of the light emitting layer are both 0.1 or more and 2 or less It is characterized by being. According to the means of claim 5, the ratio of the thickness of the n-side multilayer non-doped GaN layer to the thickness of the light-emitting barrier layer and the p-side multilayer non-doped GaN The ratio of the thickness of the light emitting layer to the thickness of the barrier layer is 0.5 to 4 in all cases. According to the means of claim 6, the number of layers of non-doped In _x1 Ga _1-x1 N (0 <x1 <1) in the n-side multilayer, and the non-doped In _{x2 in the} p-side multilayer. The number of layers made of Ga _1-x2 N (0 <x2 <1) is 1 or more and 7 or less.

  According to a seventh aspect of the present invention, a layer doped with a donor impurity is provided between the light emitting layer and the n-side multilayer. According to the eighth aspect of the present invention, the layer doped with the donor impurity is formed by stacking two or more group III nitride compound semiconductor layers each having a thickness of 5 nm or less and different compositions. It is a superlattice layer.

  According to a ninth aspect of the present invention, a layer doped with an acceptor impurity is provided between the light emitting layer and the p-side multilayer. According to the means of claim 10, the layers doped with acceptor impurities are laminated with two or more types of group III nitride compound semiconductor layers each having a thickness of 5 nm or less and different compositions. It is a superlattice layer.

As shown in the following examples, the group III nitride compound semiconductor Al _y Ga _1-yz In _z N (0 ≦ y <1, 0 <z ≦ 1 containing indium (In) forming the light emitting layer of the present invention. ), A layer made of non-doped In _x1 Ga _1-x1 N (0 <x1 <1) having a smaller indium (In) composition than the indium (In) composition z, and a layer made of non-doped GaN, A non-doped In _x2 Ga _1-x2 N (0 <x2 <1) in which the indium (In) composition z is smaller than the indium (In) composition z. ) And a non-doped GaN layer (p-side multi-layer) on the p-electrode side of the light-emitting layer, the electrostatic withstand voltage is remarkably improved, and the light emission intensity and drive voltage do not deteriorate III A group nitride compound semiconductor light emitting device could be obtained. With respect to the action that produces such an effect, the applied voltage is not concentrated on a part of the light emitting layer on the n electrode side or a part of the p electrode side, and a wide range on each of the n electrode side and the p electrode side of the light emitting layer. It is considered that the multi-layer of the present invention has an effect spreading to the above.

  An n-type layer may be provided between the light emitting layer and the n-side multiple layer, and a p-type layer may be provided between the light-emitting layer and the p-side multiple layer. When these layers are provided, the so-called clad layer and guide layer can each function. These layers may be formed of multiple layers or superlattice layers.

  A preferred embodiment of the present invention will be described. First of all, the term “non-doped” used in the present application does not mean that dopant impurities are not introduced when intentionally forming the layer, and does not exclude the case where “dopant” is mixed for some technical reason. . The technical reason is that contamination is always generated in a very small amount due to contamination from adjacent layers, contamination due to incomplete switching of the raw material introduced at the boundary where different layers are formed, or defective cleaning of the manufacturing equipment. Nation is given. These unintentionally mixed layers containing “dopants” are substantially included in the “non-doped layer” referred to in the present application.

The multiple quantum well structure constituting the light emitting layer is a well composed of a group III nitride compound semiconductor Al _y Ga _1-yz In _z N (0 ≦ y <1, 0 <z ≦ 1) containing at least indium (In) Includes layers. The structure of the light emitting layer includes, for example, a well layer made of doped or undoped Ga _1-z In _z N (0 <z ≦ 1), and a group III nitride having an arbitrary composition having a larger band gap than the well layer. Examples thereof include a barrier layer made of a physical compound semiconductor AlGaInN. A preferable example is an undoped Ga _1-z In _z N (0 <z ≦ 1) well layer and a barrier layer made of undoped GaN.

The n-side multiple layer provided on the n-electrode side of the light emitting layer and the p-side multiple layer provided on the p-electrode side, which are the main features of the present invention, are formed as follows. Group III nitride compound semiconductor Al _y Ga _1-yz In _z N (0 ≦ y <1, 0 <z ≦ 1) containing at least indium (In) forming the light emitting layer Indium (In) in the well layer An n-side multiple layer is formed by a layer made of non-doped In _x1 Ga _{1 -x1} N (0 <x1 <1) having a composition x1 of indium (In) smaller than the composition z of and a layer made of non-doped GaN. Similarly, a layer composed of non-doped In _x2 Ga _1-x2 N (0 <x2 <1) having an indium (In) composition x2 smaller than the indium (In) composition z of the well layer forming the light emitting layer, The p-side multilayer is formed by a layer made of non-doped GaN. At this time, the composition x1 of indium (In) of the layer made of non-doped In _x1 Ga _1-x1 N (0 <x1 <1) that forms the n-side multilayer, and the non-doped In _x2 that forms the p-side multilayer. The indium (In) composition x2 of the layer composed of Ga _1-x2 N (0 <x2 <1) is preferably 0.02 or more and 0.07 or less, and more preferably 0.03 or more and 0.05 or less.

Film thickness of non-doped In _x1 Ga _1-x1 N (0 <x1 <1) in the n-side multi-layer provided on the n-electrode side of the light-emitting layer and p-side multi-layer provided on the p-electrode side of the light-emitting layer The thickness of the non-doped In _x2 Ga _1-x2 N (0 <x2 <1) layer is preferably 0.5 nm or more and 6 nm or less, and more preferably 0.5 nm or more and 4 nm or less. . The light emission characteristics are described below. It has been found that the drive voltage Vf significantly increases when the thickness of the layer made of non-doped In _x1 Ga _1-x1 N (0 <x1 <1) exceeds 6 nm. This is considered to be the same for the film thickness of the layer made of non-doped In _x2 Ga _{1 -x2} N (0 <x2 <1). If these film thicknesses are less than 0.5 nm, it is difficult to adjust the film thickness, and should be avoided.

  On the other hand, it has been found that the film thickness of the n-side multi-layered layer made of non-doped GaN does not significantly change the device characteristics in the range of at least 10 to 40 nm. This is considered to be the same for the film thickness of the p-side multi-layered layer made of non-doped GaN.

The ratio of the layer thickness of the non-doped In _x1 Ga _1-x1 N (0 <x1 <1) of the n-side multilayer to the thickness of the well layer of the light-emitting layer and the non-doped In _x2 Ga of the p-side multilayer _The ratio of the thickness of the layer made of _1-x2 N (0 <x2 <1) to the thickness of the well layer of the light emitting layer is preferably 0.1 or more and 2 or less. More preferably, the thickness of the n-side multi-layer non-doped In _x1 Ga _1-x1 N (0 <x1 <1) and the p-side multi-layer non-doped In are less than the thickness of the well layer of the light-emitting layer. adjusting the _x2 Ga _1-x2 N thickness of the layer made of (0 <x2 <1). On the other hand, the ratio of the thickness of the non-doped GaN layer of the n-side multilayer and the p-side multilayer to the thickness of the barrier layer of the light emitting layer is preferably 0.5 or more and 4 or less. More preferably, it is desirable to adjust the thicknesses of the non-doped GaN layers of the n-side multilayer and the p-side multilayer to be greater than the thickness of the barrier layer of the light emitting layer.

The number of layers of non-doped In _x1 Ga _1-x1 N (0 <x1 <1) in the n-side multilayer provided on the n-electrode side of the light emitting layer and the non-doped In of the p-side multilayer provided on the p-electrode side _x2 Ga _1-x2 N number of layers made of (0 <x2 <1) is preferably set to be 1 to 7, more preferably equal to 1 to 5.

  Between the light-emitting layer and the n-side multilayer, a layer added with a donor acting as a clad or a layer added with an acceptor may be provided between the light-emitting layer and the p-side multilayer. Both or one of AlGaN: Si as the n-cladding layer and AlGaN: Mg as the p-cladding layer may be provided. Generally, it is difficult to increase the hole concentration of a group III nitride compound semiconductor as compared with the electron concentration. Therefore, it is appropriate to provide a p-cladding layer. The n-side cladding layer may be provided on the side closer to the n-electrode than the light-emitting layer of the n-side multilayer, and the p-side cladding layer is different from the light-emitting layer of the p-side multilayer. It may be provided on the side closer to the p-electrode than on the opposite side.

  The n clad layer provided between the light emitting layer and the n-side multilayer can be a superlattice layer. For example, AlGaN: Si having a thickness of 1 to 5 nm and InGaN: Si having a thickness of 1 to 5 nm can be stacked. Similarly, the p-cladding layer provided between the light-emitting layer and the p-side multilayer can be formed as a superlattice layer by laminating, for example, 1 to 5 nm thick AlGaN: Mg and 1 to 5 nm thick InGaN: Mg. .

  The group III nitride compound semiconductor light-emitting device according to the present invention can have any configuration other than the limitation related to the main configuration of the present invention. The light emitting element may be a light emitting diode (LED), a laser diode (LD), a photocoupler, or any other light emitting element. In particular, any manufacturing method can be used as a method for manufacturing a group III nitride compound semiconductor light emitting 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, molecular beam vapor phase epitaxy (MBE), metalorganic vapor phase epitaxy (MOVPE), hydride vapor phase epitaxy (HVPE), liquid phase epitaxy, etc. Is effective.

Group III nitride semiconductor layer of the electrode forming layer and the like 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.

FIG. 1 is a schematic cross-sectional view of a semiconductor light emitting device 100 according to an embodiment of the present invention. In the semiconductor light emitting device 100, as shown in FIG. 1, a buffer layer 102 made of aluminum nitride (AlN) and having a thickness of about 15 nm is formed on a sapphire substrate 101 having a thickness of about 300 μm. A layer 103 made of GaN having a thickness of about 500 nm is formed, and an n-type contact layer 104 having a thickness of about 5 μm made of GaN doped with silicon (Si) at 1 × 10 ¹⁸ / cm ³ (high carrier concentration n). ⁺ Layer) is formed.

Further, on this n-type contact layer 104, an n-side multiple layer (static structure) in which five pairs of a layer 1051 made of non-doped In _0.03 Ga _0.97 N with a thickness of 3 nm and a layer 1052 made of non-doped GaN with a thickness of 20 nm are stacked. An electric withstand voltage improvement layer) 105 is formed. Further thereon, three pairs of a well layer 1061 made of non-doped In _0.2 Ga _0.8 N with a thickness of 3 nm and a barrier layer 1062 made of non-doped GaN with a thickness of 20 nm are stacked to form a light emitting layer 106 having a multiple quantum well structure. Has been.

Further, a p-type layer 107 made of p-type Al _0.15 Ga _0.85 N having a thickness of 25 nm doped with Mg 2 × 10 ¹⁹ / cm ³ is formed on the light emitting layer 106. On the p-type layer 107, a p-side multiple layer (an electrostatic breakdown voltage improving layer) in which five pairs of a layer 1081 made of non-doped In _0.03 Ga _0.97 N with a thickness of 3 nm and a layer 1082 made of non-doped GaN with a thickness of 20 nm are stacked. ) 108 is formed. A p-type contact layer 109 made of 100-nm-thick p-type GaN doped with 8 × 10 ¹⁹ Mg was formed on the p-side multilayer (electrostatic withstand voltage improving layer) 108.

  Further, a light-transmitting thin film p-electrode 110 formed by metal vapor deposition is formed on the p-type contact layer 108, and an n-electrode 140 is formed on the n-type contact layer 104. 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 109 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 from a first layer 141 made of vanadium (V) having a thickness of about 18 nm and aluminum (Al) having a thickness of about 100 nm from above a part of the n-type contact layer 104 which is partially 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. A reflective metal layer 150 made of aluminum (Al) having a thickness of about 500 nm is formed by metal vapor deposition on the outermost lowermost portion corresponding to the bottom surface of the sapphire substrate 101. The reflective metal layer 150 may be a metal such as Rh, Ti, or W, or a nitride such as TiN or HfN.

Several semiconductor light emitting devices 100 of FIG. 1 having such a structure were prepared, and the electrostatic withstand voltage was measured with a pulse voltage of 0Ω, 200F, 30 ns by a machine model equation, and the electrostatic withstand voltage was 400 to 600V. . The results are shown on the right side of FIG. 3 (shown as “n side and p side”).
[Comparative Example]
For comparison, several semiconductor light emitting devices 900 shown in FIG. 2 were prepared. The semiconductor light emitting device 900 of FIG. 2 is obtained by removing the p-side multi-layer (electrostatic withstand voltage improving layer) 108 between the p-type layer 107 and the p-type contact layer 109 from the configuration of the semiconductor light emitting device 100 of FIG. Yes, the other configurations are the same. The electrostatic withstand voltage of the semiconductor light emitting device 900 was measured with a pulse voltage of 0Ω, 200F, and 30 ns by a machine model equation, and the electrostatic withstand voltage was 130 to 200V. The results are shown on the left side of FIG. 3 (shown as “n side only”). From this, it was found that it is effective to provide the electrostatic withstand voltage improving layer not only on the n side but on both the n side and the p side, and an extremely high electrostatic withstand voltage can be obtained.
[Comparison with other multi-layer configurations for Examples]
The electrostatic withstand voltage, the driving voltage Vf, and the total radiant flux (emission intensity) for the above embodiment will be described below with reference to the drawings in comparison with the case where the multilayer structure is partially changed. The electrostatic withstand voltage was measured with a pulse voltage of 0Ω, 200F, and 30 ns by a machine model equation. The configuration of the semiconductor light emitting device used for the measurement was the same as the configuration of the semiconductor light emitting device 900 of FIG. 2, and the layer configuration of the n-side multi-layer 105 was variously changed as the electrostatic breakdown voltage improving layer.

FIGS. 4A, 4B, and 4C show a layer 1051 made of non-doped In _0.03 Ga _0.97 N having a film thickness of 3 nm for the electrostatic breakdown voltage, drive voltage Vf, and total radiant flux of the device of the above-described embodiment. FIG. 5 is a diagram showing a case where the film thickness is 1.5 nm to 10 nm. The layer 1051 composed of non-doped In _0.03 Ga _0.97 N has a high electrostatic withstand voltage and a low driving voltage Vf in the case of an element having a film thickness of 1.5 to 3 nm, but is static in the case of an element having a film thickness of 10 nm. As a result, the withstand voltage was slightly low and the drive voltage Vf was high. On the other hand, the total radiant flux (luminescence intensity) was not greatly affected by the film thickness.

5A, 5B, and 5C show the electrostatic withstand voltage, drive voltage Vf, and total radiant flux for the element of the above example, respectively, for non-doped In _0.03 Ga _0.97 N (In composition 3 It is the figure which showed the case of 0.01 (1%) to 0.08 (8%) regarding In composition of the layer 1051 which consists of%). The layer 1051 made of non-doped InGaN can reduce the driving voltage Vf in the case of an element having an In composition of 0.03 (3%) to 0.05 (5%), but the In composition is 0.01 (1%) or 0.08 (8%). In the case of the element, the result that the drive voltage Vf was high was obtained. On the other hand, the total radiant flux (luminescence intensity) was not greatly affected by the film thickness. With respect to the electrostatic withstand voltage, the driving voltage Vf was slightly improved within a suitable range.

FIGS. 6A, 6B, and 6C show the electrostatic withstand voltage, drive voltage Vf, and total radiant flux for the device of the above-described embodiment in a silicon layer (Si) (Si) ) Along with the case of a device doped with 1 × 10 ¹⁸ / cm ³ . The GaN layer 1052 can reduce the driving voltage in the case of a non-doped element, but the driving voltage Vf is increased in the case of an element doped with silicon (Si) at 1 × 10 ¹⁸ / cm ^3. It was. On the other hand, the electrostatic withstand voltage and the total radiant flux (emission intensity) were not greatly affected by the difference between doped / non-doped.

FIGS. 7A, 7B and 7C respectively show the electrostatic withstand voltage, the driving voltage Vf, and the total radiant flux of the element of the above-described embodiment, and a layer 1051 made of non-doped In _0.03 Ga _0.97 N having a thickness of 3 nm. FIG. 5 is a diagram showing the case of an element doped with silicon (Si) at 1 × 10 ¹⁸ / cm ³ . The layer 1051 composed of In _0.03 Ga _0.97 N has a high electrostatic withstand voltage when it is not doped, and can reduce the driving voltage. However, in the case of an element doped with silicon (Si) 1 × 10 ¹⁸ / cm ³ , the electrostatic withstand voltage is low. As a result, the driving voltage Vf was increased. On the other hand, the total radiant flux (luminescence intensity) was not greatly affected by the difference between doped and non-doped.

FIGS. 8A, 8B, and 8C show a layer 1051 made of non-doped In _0.03 Ga _0.97 N having a film thickness of 3 nm for the electrostatic breakdown voltage, drive voltage Vf, and total radiant flux for the device of the above-described embodiment. FIG. 5 is a diagram showing a case where the number of pairs of layers 1052 made of non-doped GaN having a thickness of 20 nm is changed from 3 pairs to 10 pairs. The multi-layer 105 has a high electrostatic withstand voltage and a low drive voltage Vf when the configuration is 3 pairs and 5 pairs, but the electrostatic withstand voltage is low in the case of an element having the configuration of 10 pairs, and the drive voltage Vf. The result that became high was obtained. On the other hand, the total radiant flux (luminescence intensity) was not greatly affected by the difference in the number of pairs.

FIGS. 9A, 9B, and 9C show a layer 1051 made of non-doped In _0.03 Ga _0.97 N with a thickness of 3 nm for the electrostatic breakdown voltage, drive voltage Vf, and total radiant flux for the device of the above-described embodiment. And a layer 1052 composed of non-doped GaN having a thickness of 20 nm and a layer made of non-doped In _0.03 Ga _0.97 N having a thickness of 3 nm and a layer composed of non-doped Al _0.2 Ga _0.8 N having a thickness of 20 nm, and the thickness FIG. 5 is a diagram showing a case where a layer made of 3 nm non-doped GaN and a 20 nm-thick non-doped Al _0.2 Ga _0.8 N element are used. The multi-layer 105 can have a high electrostatic withstand voltage and a low driving voltage when the multi-layer 105 is composed of a layer 1051 made of non-doped In _0.03 Ga _0.97 N with a thickness of 3 nm and a layer 1052 made of non-doped GaN with a thickness of 20 nm. In the case of the other two elements, the electrostatic withstand voltage was low and the drive voltage Vf was high. On the other hand, the total radiant flux (emission intensity) was not greatly affected by the difference in the composition of the two layers constituting the multi-layer 105.

  The results of FIGS. 4 to 9 are for the semiconductor light emitting device 200 having only the n-side multi-layer 105 shown in FIG. 2, but of course the n-side multi-layer 105 of the semiconductor light-emitting device 100 shown in FIG. 1 is considered to have the same effect on the p-side multilayer 108 of the semiconductor light emitting device 100 shown in FIG.

  FIG. 10 is a schematic cross-sectional view of a semiconductor light emitting device 200 according to another embodiment of the present invention. The semiconductor light emitting device 200 of FIG. 2 is a light emitting device having a configuration in which the following two points are changed with respect to the semiconductor light emitting device 100 of FIG. The first point is that an n-cladding layer 107n made of a superlattice layer is provided between the n-side multilayer (electrostatic withstand voltage improving layer) 105 and the light-emitting layer 106 having a multiple quantum well structure. The second point is that the p-type layer 107 between the light emitting layer 106 having a multiple quantum well structure and the p-side multilayer (electrostatic withstand voltage improving layer) 108 is changed to a p-cladding layer 107p made of a superlattice layer. . The semiconductor light emitting device 200 of FIG. 2 has the same configuration as the semiconductor light emitting device 100 of FIG. 1 except for these two points, and the same corresponding components are denoted by the same reference numerals.

The n-cladding layer 107n made of a superlattice layer has a thickness of 1 nm, Si doped with 1 × 10 ¹⁸ / cm ^3, and a thickness of 1 nm and Si doped with 1 × 10 ¹⁸ / cm ³ In _0.15 Ga _0.85 N. Six pairs are stacked. P-cladding layer 107p made of super lattice layer has a film thickness 1 nm, and Al _0.2 Ga _0.8 N was 1 × 10 ¹⁹ / cm ³ doped with Mg, thickness 1 nm, an In _0.05 was 1 × 10 ¹⁹ / cm ³ doped with Mg Seven pairs of Ga _0.95 N are laminated.

  The electrostatic withstand voltage and the like of the semiconductor light emitting device 200 of FIG. 10 having such a structure is equivalent to the electrostatic withstand voltage and the like of the semiconductor light emitting device 200 of FIG. Among other device characteristics, the emission intensity increased by 10%.

The present invention is not limited to the above embodiments, and various other modifications are possible. For example, each group III nitride compound semiconductor layer may be a binary to quaternary AlGaInN having an arbitrary mixed crystal ratio. More specifically, _{"Al x Ga y In 1-xy} N (0 ≦ x ≦ 1,0 ≦ y ≦ 1,0 ≦ x + y ≦ 1) " made general formula binary represented, ternary (GaInN , AlInN, AlGaN) or a quaternary (AlGaInN) group III nitride compound semiconductor can also be used. Further, a part of N of the compound may be substituted with a group V element such as P or As. In the above embodiment, the protective film 130 is formed, but the protective film 130 may be omitted. In this example, a reflective metal layer is formed on the back surface of the sapphire substrate and a light-transmitting thin film p-electrode is provided on the p-electrode side. However, in order to obtain a flip chip type, the light is extracted from the back surface of the sapphire substrate. Therefore, the reflective metal layer on the back surface of the sapphire substrate may not be formed, and an electrode layer that doubles as the light reflecting layer may be provided on the p electrode side.

1 is a cross-sectional view of a semiconductor light emitting device 100 according to Example 1 of the present invention. Sectional drawing of the semiconductor light-emitting device 900 which concerns on a comparative example. The characteristic view which shows the result of the electrostatic withstand voltage characteristic of the semiconductor light-emitting devices 100 and 900. (A), (b), (c) is a characteristic diagram showing the relationship between the film thickness of the layer 1051 made of non-doped In _0.03 Ga _0.97 N, electrostatic withstand voltage, drive voltage Vf, and total radiant flux, respectively. (A), (b), (c) is a characteristic diagram showing the relationship between the In composition of the layer 1051 made of non-doped InGaN, electrostatic withstand voltage, drive voltage Vf, and total radiant flux, respectively. (A), (b), (c) is a characteristic diagram showing the relationship between electrostatic withstand voltage, drive voltage Vf, and total radiant flux when the GaN layer 1052 is doped with silicon and when it is not doped. (A), (b), and (c) show the relationship between electrostatic withstand voltage, drive voltage Vf, and total radiant flux when the layer 1051 made of In _0.03 Ga _0.97 N is doped with silicon or not. Characteristic diagram. (A), (b), (c) is a characteristic diagram showing the relationship between the number of pairs of the multilayer 105, electrostatic withstand voltage, drive voltage Vf, and total radiant flux, respectively. (A), (b), (c) is a characteristic diagram showing the relationship between the composition of the two layers constituting the multi-layer 105, the electrostatic withstand voltage, the driving voltage Vf, and the total radiant flux, respectively. Sectional drawing of the semiconductor light-emitting device 200 which concerns on Example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100: Semiconductor light-emitting device 101: Sapphire substrate 102: Buffer layer 103: Non-doped GaN layer 104: High carrier concentration n ⁺ layer 105: n side multiple layer (electrostatic withstand voltage improvement layer)
106: Light-emitting layer 107: p-type semiconductor layer 108: p-side multilayer (electrostatic withstand voltage improvement layer)
109: p-type contact layer 110: translucent thin film p-electrode 120: p-electrode 130: protective film 140: n-electrode 150: reflective metal layer

Claims (10)

In a group III nitride compound semiconductor light emitting device having a light emitting layer having a multiple quantum well structure,
On the n-electrode side of the light emitting layer, there is an n-side multiple layer of a layer made of non _- doped In _x1 Ga _1-x1 N (0 <x1 <1) and a layer made of non-doped GaN,
On the p-electrode side of the light emitting layer, there is a p-side multiple layer of a layer made of non _- doped In _x2 Ga _1-x2 N (0 <x2 <1) and a layer made of non-doped GaN,
The well layer of the light emitting layer having the multiple quantum well structure is composed of a group III nitride compound semiconductor Al _y Ga _1-yz In _z N (0 ≦ y <1, 0 <z ≦ 1) containing at least indium (In). ,
In _x1 Ga _1-x1 N (0 <x1 <1) forming the n-side multilayer, the composition x1 of indium (In) and In _x2 Ga _1-x2 N (forming the p-side multilayer) The indium (In) composition x2 of the layer consisting of 0 <x2 <1) is smaller than the indium (In) composition z of the well layer of the light emitting layer of the multiple quantum well structure. Group nitride compound semiconductor light emitting device. Non-doped In _x1 Ga _1-x1 N (0 <x1 <1) composition x1 of the n-side multilayer and non-doped In _x2 Ga _1-x2 N of the p-side multilayer 2. The group III nitride compound semiconductor light-emitting device according to claim 1, wherein the composition x2 of indium (In) in the layer composed of (0 <x2 <1) is 0.02 or more and 0.07 or less. The thickness of the n-side multilayer non-doped In _x1 Ga _1-x1 N (0 <x1 <1) and the p-side multilayer non-doped In _x2 Ga _1-x2 N (0 <x2 <1 3. The group III nitride compound semiconductor light-emitting element according to claim 1, wherein a thickness of each of the layers is 0.5 nm or more and 6 nm or less. The ratio of the thickness of the non-doped In _x1 Ga _1-x1 N (0 <x1 <1) of the n-side multilayer to the thickness of the well layer of the light-emitting layer, and the non-doped of the p-side multilayer The ratio of the thickness of the layer made of In _x2 Ga _1-x2 N (0 <x2 <1) to the thickness of the well layer of the light emitting layer is 0.1 or more and 2 or less, respectively. The group III nitride compound semiconductor light-emitting device according to any one of claims 1 to 3. The ratio of the thickness of the non-doped GaN layer of the n-side multilayer to the thickness of the barrier layer of the light-emitting layer, and the barrier of the light-emitting layer of the thickness of the non-doped GaN layer of the p-side multilayer 5. The group III nitride compound semiconductor light-emitting element according to claim 1, wherein the ratio of the thickness to the layer is 0.5 or more and 4 or less. The number of layers of the non-doped In _x1 Ga _1-x1 N (0 <x1 <1) in the n-side multilayer and the non-doped In _x2 Ga _1-x2 N (0 <x2 <in the p-side multilayer) The group III nitride compound semiconductor light-emitting device according to any one of claims 1 to 5, wherein the number of layers comprising 1) is 1 or more and 7 or less. The group III nitride compound semiconductor light emitting device according to any one of claims 1 to 6, further comprising a layer doped with a donor impurity between the light emitting layer and the n-side multilayer. element. The layer doped with the donor impurity is a superlattice layer in which two or more types of group III nitride compound semiconductor layers each having a thickness of 5 nm or less and different compositions are stacked. Item 8. The group III nitride compound semiconductor light-emitting device according to item 7. 9. The group III nitride compound semiconductor light-emitting device according to claim 1, further comprising a layer doped with an acceptor impurity between the light emitting layer and the p-side multilayer. 10. element. The layer doped with the acceptor impurity is a superlattice layer in which two or more group III nitride compound semiconductor layers each having a thickness of 5 nm or less and different compositions are stacked. Item 13. A group III nitride compound semiconductor light-emitting device according to Item 9.

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