Semiconductor light-emitting element

Abstract

This disclosure involves: a substrate; and a semiconductor structure layer including an n-type semiconductor layer formed from AlGaN formed on the substrate, an active layer formed on the n-type semiconductor layer, and a p-type semiconductor layer formed on the active layer and formed from AlGaN co-doped with Mg and Si. In the p-type semiconductor layer, the concentration ratio that is the ratio of the concentration of Si to the concentration of Mg is 0.055 or more.

Description

Semiconductor light emitting device

[0001] The present invention relates to a semiconductor light emitting device.

[0002] Semiconductor light-emitting devices made of nitride semiconductors have been disclosed. For example, Non-Patent Document 1 discloses a light-emitting device including an n-type semiconductor layer, an active layer, and a p-type semiconductor layer, each of which is made of aluminum gallium nitride (AlGaN).

[0003] Furthermore, for example, Patent Document 1 discloses a light-emitting device including an n-side nitride semiconductor layer, an active layer, and a p-side nitride semiconductor layer, in which the p-side nitride semiconductor layer includes a p-side cladding layer, an aluminum nitride (AlN) layer, and an undoped gallium nitride (GaN) layer.

[0004] XACao et al., IEEE Electron Device Letters, Vol.27, No.5 (2006)

[0005] Japanese Patent Application Laid-Open No. 2013-197512

[0006] In the light-emitting element disclosed in Non-Patent Document 1, the peak intensity of light emitted from the light-emitting element decreases as the temperature rises due to driving of the light-emitting element. Furthermore, although Patent Document 1 discloses that the degree of decrease in light output can be suppressed in a temperature characteristic evaluation, the light output still continues to decrease as the temperature of the element rises.

[0007] The present invention has been made in view of the above-mentioned points, and has as its object to provide a semiconductor light emitting device in which the light output is less likely to decrease even when the device temperature rises.

[0008] A semiconductor light-emitting device according to the present invention comprises a substrate, an n-type semiconductor layer made of AlGaN formed on the substrate, an active layer formed on the n-type semiconductor layer, and a p-type semiconductor layer made of AlGaN co-doped with Si and Mg formed on the active layer, wherein a concentration ratio, which is a ratio of the Si concentration to the Mg concentration in the p-type semiconductor layer, is 0.055 or more.

[0009] Fig. 1 is a top view of a light-emitting element according to Example 1. Fig. 2 is a cross-sectional view of the light-emitting element according to Example 1. Fig. 3 is a diagram showing a band diagram of the light-emitting element according to Example 1. Fig. 4 is a table showing the configuration conditions of samples in evaluation of the light-emitting element according to Example 1. Fig. 5 is a graph showing evaluation results of the light-emitting element according to Example 1.

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same components are designated by the same reference numerals, and the description of the same components will be omitted.

[0011] [Outline of Light-Emitting Element 100] The configuration of the light-emitting element 100 according to Example 1 will be described with reference to Fig. 1 to Fig. 3. Fig. 1 is a top view of the light-emitting element 100 according to Example 1. Fig. 2 is a cross-sectional view of the light-emitting element 100 taken along line 2-2 shown in Fig. 1. Fig. 3 is a diagram showing a band diagram of the light-emitting element 100.

[0012] The light-emitting element 100 is a light-emitting diode (LED) that includes an element substrate 11 and a semiconductor structure layer EM that is formed on the element substrate 11 and includes an n-type semiconductor layer 13, an active layer 15, an electron blocking layer 17, and a p-type semiconductor layer 19.

[0013] [Element Substrate 11] First, the element substrate 11 will be described. The element substrate 11 is a flat substrate having a rectangular upper surface and having insulating and light-transmitting properties. In the light-emitting element 100, the element substrate 11 is made of single-crystal aluminum nitride (AlN). The element substrate 11 also functions as a growth substrate for growing crystals of the semiconductor structure layer EM on the element substrate 11.

[0014] The device substrate 11 has a dislocation density of 10 to suppress the occurrence of defects that may cause non-radiative recombination in the active layer 15 described later. ８ cm －２ In the light emitting device 100 of this embodiment, the dislocation density of the device substrate 11 is preferably 10 ５ cm －２ The following is the result.

[0015] Furthermore, since a large surface roughness of the element substrate 11 can cause abnormal growth of the semiconductor structure layer EM grown on the element substrate 11, it is preferable that the element substrate 11 is manufactured so that the surface roughness is equal to or less than a predetermined value. ２ The root mean square roughness (RMS) in this range is, for example, 0.1 nm or less.

[0016] [Semiconductor Structure Layer EM] Next, the configuration of the semiconductor structure layer EM and the electrodes formed on the semiconductor structure layer EM will be described. The n-type semiconductor layer 13 is a semiconductor layer made of aluminum gallium nitride (AlGaN) doped with silicon (Si) as an n-type impurity. In the light-emitting element 100 of this embodiment, the concentration of Si doped in the n-type semiconductor layer 13 is 1×10 １９ cm －３ is.

[0017] In addition, the concentration of Si in the n-type semiconductor layer 13 is set to 1×10 in consideration of reducing the resistance value so as to obtain conductivity of the n-type semiconductor layer 13. １８ ~1 x 10 ２０ cm －３ It is preferable that the range is 5×10 １８ ~5 x 10 １９ cm －３ It is preferable that the range is within the range of

[0018] The n-type semiconductor layer 13 is composed of a first n-type AlGaN layer 13A and a second n-type AlGaN layer 13B. The first n-type AlGaN layer 13A is formed across the upper surface of the element substrate 11. The first n-type AlGaN layer 13A is a so-called compositionally graded layer in which the Al composition changes from the lower surface side to the upper surface side.

[0019] Specifically, the Al composition of the first n-type AlGaN layer 13A is set to Al ｘ１ Ga （１－ｘ１） When x1 is N, x1 gradually decreases from 1.0 to 0.75 from the bottom surface to the top surface. As a result, the band gap of the first n-type AlGaN layer 13A gradually decreases from the bottom surface to the top surface, as shown in FIG.

[0020] The second n-type AlGaN layer 13B is formed over the upper surface of the first n-type AlGaN layer 13A and functions as a cladding layer in the light-emitting device 100. The second n-type AlGaN layer 13B is a so-called compositionally graded layer in which the Al composition changes from the lower surface side to the upper surface side.

[0021] Specifically, the Al composition of the second n-type AlGaN layer 13B is set to Al ｘ２ Ga （１－ｘ２） When x2 is N, x2 gradually decreases from 0.75 to 0.70 from the bottom surface to the top surface. As a result, the band gap of the second n-type AlGaN layer 13B gradually decreases from the bottom surface to the top surface, as shown in FIG.

[0022] The second n-type AlGaN layer 13B includes a flat first portion 13B1 formed across the upper surface of the first n-type AlGaN layer 13A and a second portion 13B2 protruding upward in Fig. 2 from a region including the outer edge of the first portion 13B1. In other words, the second n-type AlGaN layer 13B has a mesa-shaped structure.

[0023] If the n-type semiconductor layer 13 is too thick, lattice relaxation occurs and dislocations are likely to occur, so the total thickness is preferably in the range of 500 to 2000 nm. In the light-emitting device 100 of this embodiment, the thickness of the first n-type AlGaN layer 13A is 200 nm, and the thickness from the lower surface of the first portion 13B1 to the upper surface of the second portion 13B2 of the second n-type AlGaN layer 13B is 1000 nm.

[0024] In addition, in consideration of transmitting light emitted from the active layer 15 described below, the n-type semiconductor layer 13 preferably has an Al composition higher than that of the active layer 15 .

[0025] The active layer 15 is a semiconductor layer that is formed over the upper surface of the second portion 13B2 of the second n-type AlGaN layer 13B and emits light by recombination of electrons and holes. When the light-emitting device 100 is driven, the active layer 15 emits deep ultraviolet light having a peak wavelength in the range of 210 to 300 nm, for example.

[0026] In the light emitting device 100 of this embodiment, the active layer 15 is made of Al ０．６ Ga ０．４ A barrier layer made of N and Al ０．５ Ga ０．５ The active layer 15 has a multi-quantum well (MQW) structure in which three layers of N well layers are alternately stacked. In the active layer 15, for example, the barrier layers are 7 nm thick and the well layers are 4 nm thick.

[0027] The composition ratio of the barrier layer of the active layer 15 is Al Ａ１ Ga （１－Ａ１） N, and the composition ratio of the well layer is Al Ａ２ Ga （１－Ａ２） When N is used, the Al composition relationship is preferably A2<A1≦1.0, taking into consideration obtaining the desired emission wavelength. The thickness of the barrier layer is preferably within the range of 2 to 10 nm, and the thickness of the well layer is preferably within the range of 2 to 15 nm. The number of quantum wells in the active layer 15 is not particularly limited and can be appropriately determined within the range of, for example, 1 to 5 layers.

[0028] In addition, both or either one of the barrier layer and well layer of the active layer 15 may be an n-type layer doped with Si. In this case, the concentration of the doped Si is 1×10 １７ ~5 x 10 １８ cm －３ It is preferable that the range is within the range of

[0029] The electron blocking (EB) layer 17 (hereinafter also referred to as the EB layer 17) is a semiconductor layer made of AlN formed on the active layer 15. The EB layer 17 has a function of preventing electrons injected from the n-type semiconductor layer 13 into the active layer 15 from overflowing into the p-type semiconductor layer 19 (described later). Therefore, the EB layer 17 is configured to have a larger band gap than the active layer 15, as shown in FIG. 3 .

[0030] In the light emitting device 100, the EB layer 17 is composed of an undoped first EB layer 17A formed over the upper surface of the active layer 15 and a p-type second EB layer 17B formed over the upper surface of the first EB layer 17A and doped with magnesium (Mg) as a p-type impurity. In the light emitting device 100 of this example, the concentration of Mg doped in the second EB layer 17B is 4.99×10 １９ cm －３ is.

[0031] The concentration of Mg in the second EB layer 17B is set to 5×10 １８ ~1 x 10 ２０ cm －３ From the viewpoint of increasing the efficiency of carrier injection into the active layer 15, it is preferable that the concentration of the carriers is in the range of 1×10 １９ ~8 x 10 １９ cm －３ It is more preferable that the range is within the range of

[0032] Furthermore, compared to a mixed crystal (AlGaN) of AlN and GaN, which have different lattice constants, AlN can suppress the generation of N vacancies that generate n-type carriers (electrons) by adding Mg. Therefore, AlN is preferably used as the material for the EB layer 17.

[0033] The second EB layer 17B may contain no Si or may contain Si at a concentration lower than the concentration doped into the p-type AlGaN layer 19A described later. For example, the concentration of Si doped into the second EB layer 17B may be 1×10 １８ cm －３ It is preferable that:

[0034] Since Si suppresses the generation or migration of N vacancies, when the second EB layer 17B is doped with Si, it is possible to suppress the change in the carrier profile over time. That is, since it is possible to suppress the change in the carrier concentration of the second EB layer 17B over time, it is possible to stabilize the injection of carriers (holes) into the active layer 15.

[0035] The thickness of the EB layer 17 is preferably in the range of 2 to 20 nm, and more preferably 5 to 15 nm, in consideration of the fact that the EB layer 17 serves as an electron blocking layer and efficiently injects holes from the p-type semiconductor layer 19 described below into the active layer 15. In the light emitting device 100 of this embodiment, the thickness of the first EB layer 17A is 2 nm, and the thickness of the second EB layer 17B is 8 nm.

[0036] The p-type semiconductor layer 19 is a semiconductor layer doped with Mg as a p-type impurity, and is composed of a p-type AlGaN layer 19A made of AlGaN and a p-type GaN layer 19B made of GaN formed thereon.

[0037] The p-type AlGaN layer 19A is formed over the upper surface of the second EB layer 17B and functions as a cladding layer in the light emitting device 100. The p-type AlGaN layer 19A is a so-called compositionally graded layer in which the Al composition changes from the lower surface side to the upper surface side.

[0038] Specifically, the Al composition of the p-type AlGaN layer 19A is ｙ１ Ga （１－ｙ１） When y1 is N, y1 gradually decreases from 1.0 to 0.8 from the bottom surface to the top surface. As a result, the band gap of the p-type AlGaN layer 19A gradually decreases from the bottom surface to the top surface, as shown in FIG.

[0039] When changing y1 of the p-type AlGaN layer 19A as described above, in consideration of increasing the efficiency of hole injection from the p-type AlGaN layer 19A to the active layer 15, it is preferable to set y1 at the bottom surface of the p-type AlGaN layer 19A to 0.95 to 1.0, and it is preferable to set y1 at the top surface of the p-type AlGaN layer 19A to 0.60 to 0.85.

[0040] In the p-type AlGaN layer 19A, y1 may be a constant value, and preferably y1 is within a range of 0.5 to 1.0, for example. Furthermore, in consideration of suppressing carrier overflow from the active layer 15 even when a large amount of current is injected, it is more preferable that the difference between y1 and the Al composition (the above-mentioned A1) of the barrier layer of the active layer 15 is 0.5 or more.

[0041] In the light emitting device 100, the p-type AlGaN layer 19A is doped with Si as an n-type impurity in addition to Mg as a p-type impurity, i.e., the p-type AlGaN layer 19A is co-doped with Mg and Si.

[0042] In the light emitting device 100 of this example, the Mg concentration in the p-type AlGaN layer 19A is 4.80×10 １９ cm －３ and the concentration of Si is 3.98×10 １８ cm －３ In this case, the concentration ratio, which is the ratio of the Si concentration to the Mg concentration in the p-type AlGaN layer 19A, is 0.083. Furthermore, the concentration ratio when the Si concentration is used as the reference is 12.1.

[0043] The concentration of Mg in the p-type AlGaN layer 19A is set to 1.0×10 １７ ~1.2 × 10 ２０ cm －３ In addition, the concentration of Si in the p-type AlGaN layer 19A is preferably in the range of 1.8×10 １８ ~8.0 x 10 １８ cm －３ In addition, the concentration ratio of Si to Mg in the p-type AlGaN layer 19A is preferably in the range of 0.009 to 0.185, in order to ensure a good output maintenance rate of the emitted light.

[0044] In particular, p-type Al having an Al composition ratio y1 of 0.8 to 1.0 ｙ１ Ga （１－ｙ１） In the N layer 19A, the Si concentration is 3.3×10 １８~4.0 x 10 １８ cm －３ and the Mg concentration is 4.8 × 10 １９ ~6.3 x 10 １９ cm －３ It is preferable to set the concentration range of Si and Mg as described above. By setting the concentration range of Si and Mg as described above, it is possible to prevent the generation or migration of defects (e.g., N vacancies) that generate n-type carriers due to the addition of Mg, even in high temperature ranges (e.g., 50°C to 125°C). As a result, the light output of the light-emitting device 100 increases even in high temperature ranges (e.g., 50°C to 125°C). In other words, Mg carriers (holes) activated in high temperature ranges are injected into the active layer 15 without being lost due to defects that generate n-type carriers.

[0045] In the light-emitting device 100 of this embodiment, the thickness of the p-type AlGaN layer 19A is 60 nm. Note that if the thickness of the p-type AlGaN layer 19A is less than 10 nm, it becomes difficult to obtain the effect of suppressing carrier overflow, and if it exceeds 150 nm, there is a risk that the resistance value will become too high. Therefore, the thickness is preferably 40 to 120 nm, and more preferably 50 to 100 nm.

[0046] The p-type GaN layer 19B is formed over the upper surface of the p-type AlGaN layer 19A. The p-type GaN layer 19B has a thickness of 1×10 １８ ~2 x 10 ２０ cm －３ It is preferable that the Mg concentration is in the range of 1000 to 15000.

[0047] In the light emitting device 100 of this embodiment, the thickness of the p-type GaN layer 19B is set to 270 nm. In consideration of the resistance value of the p-type GaN layer 19B, which is related to the operating voltage when the light emitting device 100 is driven, the thickness of the p-type GaN layer 19B is preferably set in the range of about 5 to 500 nm.

[0048] Next, the n-electrode NE and the p-electrode PE will be described. The n-electrode NE is an electrode electrically connected to the first portion 13B1 exposed from the second portion 13B2 of the second n-type AlGaN layer 13B. The n-electrode NE is formed by stacking, for example, titanium (Ti) and gold (Au) in this order on the first portion 13B1.

[0049] The p-electrode PE is an electrode electrically connected to the p-type GaN layer 19B of the p-type semiconductor layer 19. The p-electrode PE is formed by stacking, for example, nickel (Ni) and Au in this order on the p-type GaN layer 19B.

[0050] In addition, for example, a translucent indium tin oxide (ITO) electrode may be provided between the p-type GaN layer 19B and the p-electrode PE in order to achieve better ohmic contact between the p-type GaN layer 19B and the p-electrode PE.

[0051] In the light-emitting element 100, when a voltage is applied to the p-electrode PE and the n-electrode NE and a current flows between the p-electrode PE and the n-electrode NE, a current flows in the active layer 15 of the semiconductor structure layer EM and deep ultraviolet light is emitted.

[0052] The deep ultraviolet light emitted from the active layer 15 by application of a voltage to the p-electrode PE and the n-electrode NE may proceed directly to the element substrate 11 or may be reflected by the p-electrode PE and then incident on the element substrate 11. Therefore, in the light-emitting element 100, the lower surface of the element substrate 11 serves as the light-emitting surface of the light-emitting element 100.

[0053] [Manufacturing Method of Light-Emitting Device 100] A manufacturing method of the light-emitting device 100 in this example will be described below. First, a wafer that will serve as the base of the element substrate 11 is prepared (substrate preparation step). Specifically, an AlN film is formed by hydride vapor phase epitaxy (HVPE) on the C-plane ((0001) plane) of an AlN seed substrate that has been fabricated by physical vapor transport (PVT).

[0054] Next, a semiconductor structure layer EM is formed on the wafer prepared in the substrate preparation step (semiconductor structure layer formation step). Specifically, first, semiconductor layers corresponding to the n-type semiconductor layer 13, the active layer 15, the EB layer 17, and the p-type semiconductor layer 19 are formed in this order on the wafer at a growth temperature of, for example, 1000 to 1200° C. using a known crystal growth method such as metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE).

[0055] Thereafter, a partial region of the upper surface of the p-type semiconductor layer 19 is etched by inductively coupled plasma (ICP) dry etching until the first portion 13B1 of the second n-type AlGaN layer 13B is exposed, thereby forming the semiconductor structure layer EM having the second n-type AlGaN layer 13B having the above-described mesa shape.

[0056] Next, an n-electrode NE and a p-electrode PE are formed on the semiconductor structure layer EM (electrode formation step). Specifically, Ti and Au are first stacked on the exposed portion of the first portion 13B1 of the second n-type AlGaN layer 13B in the semiconductor structure layer EM, and a heat treatment is performed at a temperature of 900° C. in a nitrogen atmosphere. This forms the n-electrode NE.

[0057] Thereafter, Ni and Au are stacked on the upper surface of the p-type GaN layer 19B of the p-type semiconductor layer 19 in the semiconductor structure layer EM, and heat treatment is performed in an oxygen atmosphere at a temperature of 500° C. A p-electrode PE is formed.

[0058] Finally, the back side of the wafer (the side opposite to the surface on which the semiconductor structure layer EM is formed) is mechanically polished so that the wafer has a predetermined thickness, and then the light-emitting elements 100 are singulated by dicing (singulation step).

[0059] When the light emitting element 100 manufactured by the above process is provided on a submount substrate, the light emitting element 100 is mounted by, for example, flip-chip mounting. Specifically, the n-electrode NE and p-electrode PE of the light emitting element 100 are respectively bonded to n-side wiring pads and p-side wiring pads provided on the submount substrate via bonding members such as gold-tin (AuSn) solder.

[0060] [Temperature Characteristic Evaluation of Light-Emitting Element] Hereinafter, the contents and results of the temperature characteristic evaluation performed on a plurality of samples including the light-emitting element 100 of this example will be described with reference to FIGS.

[0061] 4 is a table showing the configurations of samples prepared for evaluating the temperature characteristics of the light output of the light-emitting element 100 in this example. Of Samples 1 to 4 shown in the table in FIG. 4, Sample 1 is the light-emitting element 100 in Example 1 described above.

[0062] FIG. 4 shows the Mg concentration of the second EB layer 17B, the Si concentration of the p-type AlGaN layer 19A, the Mg concentration of the p-type AlGaN layer 19A, the ratio of the Si concentration to the Mg concentration of the p-type AlGaN layer 19A (hereinafter also referred to as the Si / Mg ratio), and the ratio of the Mg concentration of the second EB layer 17B to the Mg concentration of the p-type AlGaN layer 19A for Samples 1 to 4.

[0063] The difference between Samples 1 to 4 is mainly in the Mg concentration in the p-type AlGaN layer 19A. For example, the Mg concentration in the p-type AlGaN layer 19A of Sample 1 and Sample 2 is 4.80×10 １８ cm －３ and 5.21 x 10 １８ cm －３ is 5.00 × 10 １８ cm －３ It's before and after.

[0064] For example, the Mg concentration in the p-type AlGaN layer 19A of Sample 3 and Sample 4 is 6.03×10 １８ cm －３ and 6.27 x 10 １８ cm －３ is 6.00 × 10 １８ cm －３That is, the Mg concentrations of Samples 1 and 2 are set lower than the Mg concentrations of Samples 3 and 4.

[0065] The Si / Mg ratios of Samples 1 to 4 were 0.083, 0.066, 0.055, and 0.059, respectively, and the Mg / Si ratios of Samples 1 to 4 were 12.1, 15.1, 18.1, and 16.9, respectively.

[0066] 5 is a graph showing the change in optical output when the device temperature is increased for each of Samples 1 to 4 shown in the table of FIG. 5. In FIG. 5, the horizontal axis of the graph is the junction temperature T ｊ The vertical axis of the graph indicates the relative output of deep ultraviolet light emitted from each sample.

[0067] In this evaluation, a forward current of 440 mA was applied to each of Samples 1 to 4, and the junction temperature T ｊ The light output was measured while the temperature was changed in the range of 50 to 125°C, and the measured light output was used to obtain the relative light output. The relative light output was calculated by setting the light output when current started to flow in each of Samples 1 to 4, i.e., the light output when the device started to operate, as 1.

[0068] From the graph in FIG. 5, the junction temperature T ｊ It can be seen that the light output increases as the value of λ increases. Specifically, the relative light output of Samples 1 and 2, which are the light-emitting devices 100 of the embodiment, increases linearly. On the other hand, Samples 3 and 4 exhibit behavior different from Samples 1 and 2, and the relative light output increases gradually.

[0069] From the above results, in each of Samples 1 to 4, in the Mg concentration range in which the Si / Mg ratio (the Mg / Si ratio in parentheses) of the p-type AlGaN layer 19A is 0.055 (18.1) to 0.083 (12.1), the junction temperature T ｊ It can be seen that the light output increases as the

[0070] More specifically, in the Mg concentration range in which the Si / Mg ratio of the p-type AlGaN layer 19A is 0.083 (12.1) to 0.066 (15.1), the junction temperature T ｊ In contrast, in the Mg concentration range where the Si / Mg ratio of the p-type AlGaN layer 19A is 0.055 (18.1) to 0.059 (16.9), the junction temperature T ｊ As the temperature increases, the light output slows down (saturates).

[0071] That is, when the light-emitting element 100 is operated at high temperatures, a light output proportional to the rise in junction temperature Tj can be obtained by setting the Si / Mg ratio in the range of 0.083 (12.1) to 0.066 (15.1). In other words, when the ratio of the Mg addition amount to the Si addition amount is 12 to 15 times, the generation or movement of defects that generate n-type carriers due to the addition of Mg can be sufficiently suppressed.

[0072] Furthermore, when the Si / Mg ratio of the p-type AlGaN layer 19A is set to 0.055 to 0.083, the ratio of the Mg concentration of the second EB layer 17B to the Mg concentration of the p-type AlGaN layer 19A can be set to 0.831 to 1.040. In this way, by using AlN for the EB layer 17, the Mg concentration of the second EB layer 17B can be made equal to the Mg concentration of the p-type AlGaN layer without adding Si.

[0073] Furthermore, by using AlN for the EB layer 17, it is possible to obtain optical output proportional to the increase in junction temperature Tj when the ratio of the Mg concentration in the second EB layer to the Mg concentration in the p-type AlGaN layer 19A is in the range of 0.835 to 1.040. In other words, by using AlN for the EB layer 17, it is possible to suppress the occurrence or migration of defects that generate n-type carriers due to the addition of Mg without the addition of Si.

[0074] Furthermore, from the above results, the junction temperature T ｊ In order to obtain a light emitting device 100 in which the optical output increases as the Mg concentration of the second EB layer 17B increases, for example, １９ cm －３ ~5.21 x 10 １９ cm－３ In order to show a better increasing trend, it is better to keep it within the range of 4.35 × 10 １９ cm －３ ~4.99 x 10 １９ cm －３ It can be seen that it is sufficient to keep it within the range of

[0075] From the above results, the inventors of the present invention have concluded that the junction temperature T ｊ It has been found that it is possible to realize a light emitting device whose light output increases as the temperature rises.

[0076] Therefore, according to the light-emitting element 100 of this embodiment, even if the junction temperature rises as the light-emitting element is driven, it is possible to suppress a decrease in light output, and it is possible to overcome the problem of a decrease in light output when used under high-temperature conditions or when driven continuously for long periods of time.

[0077] In the light emitting device 100 of this embodiment, the element substrate 11 is made of single crystal AlN, but this is not limiting. For example, the element substrate 11 may be made of sapphire (Al ２ O ３ Alternatively, a substrate may be used in which an AlN layer is laminated on a substrate made of AlN.

[0078] In the light emitting device 100 of this embodiment, the Al composition of the first n-type AlGaN layer 13A is ｘ１ Ga （１－ｘ１） When x1 is N, x1 gradually decreases from 1.0 to 0.75 from the bottom surface to the top surface, but this is not limiting and, for example, x1 may be a constant value.

[0079] In the light emitting device 100 of this embodiment, the Al composition of the second n-type AlGaN layer 13B is ｘ２ Ga （１－ｘ２） When x2 is N, x2 gradually decreases from 0.75 to 0.70 from the lower surface to the upper surface, but this is not limiting and, for example, x2 may be a constant value.

[0080] 100 Light emitting element 11 Support substrate 13 N-type semiconductor layer 15 Active layer 17 Electron blocking layer 19 P-type semiconductor layer

Claims

1. A semiconductor light-emitting device comprising: a substrate; an n-type semiconductor layer made of AlGaN formed on said substrate; an active layer formed on said n-type semiconductor layer; and a p-type semiconductor layer made of AlGaN co-doped with Si and Mg formed on said active layer, wherein the concentration ratio of Si to Mg in said p-type semiconductor layer is 0.055 or greater.

2. The Mg concentration in the p-type semiconductor layer is 4.80×10 １９ cm －３ ~6.27 x 10 １９ cm －３ 2. The semiconductor light emitting device according to claim 1, wherein the range is:

3. The semiconductor structure layer has an electron blocking layer formed between the active layer and the p-type semiconductor layer and doped with Mg, and the Mg concentration in the electron blocking layer is 4.35×10 １９ cm －３ ~5.21 x 10 １９ cm －３ 3. The semiconductor light emitting element according to claim 1, wherein the range is:

4. The semiconductor light-emitting device according to claim 3, wherein the electron blocking layer is made of AlN.

5. The semiconductor light-emitting device according to claim 1 or 2, wherein the concentration ratio is 0.066 or more.

6. The Al composition of the p-type semiconductor layer is ｙ１ Ga （１－ｙ１） 3. The semiconductor light emitting device according to claim 1, wherein y1 is in the range of 0.5 to 1.0 when N is taken as N.

7. The semiconductor light-emitting device according to claim 6, wherein the Al composition of said p-type semiconductor layer changes so that y1 gradually decreases from 1.0 to 0.8 from the lower surface to the upper surface of said p-type semiconductor layer.

8. A semiconductor light-emitting device comprising: a substrate; an n-type semiconductor layer made of AlGaN formed on the substrate; an active layer formed on the n-type semiconductor layer; and a p-type semiconductor layer made of AlGaN co-doped with Si and Mg formed on the active layer, wherein the light output increases as the junction temperature increases.

9. The semiconductor light-emitting device according to claim 1 or 8, wherein deep ultraviolet light is emitted from the active layer.

Images