Iii-nitride semiconductor light emitting device

Abstract

The present disclosure relates to a method for manufacturing a group 3 nitride semiconductor light-emitting structure in general, and in particular to a method for manufacturing a group 3 nitride semiconductor (a compound of Al(x)Ga(y)In(1-xy)N (0≤x≤1, 0≤y≤1, 0≤x+y≤1)) light-emitting structure capable of shifting the light emission wavelength toward the long wavelength side through a suitable barrier layer.

Description

Technology Field

[0001] The present disclosure relates to a method for manufacturing a group 3 nitride semiconductor light-emitting structure in general, and in particular to a method for manufacturing a group 3 nitride semiconductor light-emitting structure capable of shifting the emission wavelength toward the long wavelength side through a suitable barrier layer. Here, the group 3 nitride semiconductor is composed of a compound of Al(x)Ga(y)In(1-xy)N (0≤x≤1, 0≤y≤1, 0≤x+y≤1). Background Technology

[0002] This section provides background information related to the present disclosure, which is not necessarily prior art.

[0003] Currently, commercial red light-emitting semiconductor light-emitting devices (e.g., LEDs, LDs) are manufactured using AlGaInP-based compound semiconductors, but recently, yellow, amber, orange, red, and infrared light-emitting devices are being investigated using a group 3 nitride semiconductor light-emitting structure in which InGaN, a group 3 nitride semiconductor, is used as the active region.

[0004] FIG. 1 is a diagram illustrating an example of a conventional red-emitting group III nitride semiconductor light-emitting device, wherein the semiconductor light-emitting device comprises a growth substrate (10; e.g., a patterned C-plane sapphire substrate (PSS)), a buffer region (20; e.g., un-doped GaN (2 μm) formed on a seed layer (low-temperature grown GaN)), and an n-side contact region (30; e.g., Si-doped GaN (2–8 μm) and Si-doped Al 0.03 Ga 0.97 N (1㎛)), superlattice region (31; e.g., 15 period GaN (6nm) / In 0.08 Ga0.92 N (2 nm)), 15 nm thick Si-doped GaN (32), quantum well structure with low In content (41: e.g.: In 0.2 Ga 0.8 Quantum well made of N (2nm) and GaN (2nm) / Al 0.13 Ga 0.87 Barrier layer made of N (18 nm) / GaN (3 nm), red light-emitting active region (42; e.g., quantum well made of InGaN (2.5 nm) - AlN (1.2 nm) / GaN (2 nm) / Al 0.13 Ga 0.87 It includes a barrier layer made of N (18 nm) / GaN (3 nm) - a quantum well made of InGaN (2.5 nm) - a barrier layer made of AlN (1.2 nm) / GaN (23 nm), a GaN layer (43) with a thickness of 15 nm, a p-side region (50; e.g., Mg-doped GaN (100 nm) and p+-GaN:Mg (10 nm)), a current diffusion electrode (60; e.g., ITO), a first electrode (70; e.g., Cr / Ni / Au) and a second electrode (80; e.g., Cr / Ni / Au) (Paper: 633-nm InGaN-based red LEDs grown on thick underlying GaN layers with reduced in-plane residual stress; Applied Physics Letters, April 2020).

[0005] In addition, U.S. Patent Publication No. US10,396,240 discloses a red light-emitting semiconductor light-emitting device utilizing an InGaN active region. The problem to be solved

[0006] This is described at the end of 'Specific details for implementing the invention'. means of solving the problem

[0007] This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features.

[0008] According to one aspect of the present disclosure, a method for manufacturing a group 3 nitride semiconductor light-emitting structure is provided. Effects of the invention

[0009] This is described at the end of 'Specific details for implementing the invention'. Brief explanation of the drawing

[0010] FIG. 1 is a drawing showing an example of a conventional red-emitting group 3 nitride semiconductor light-emitting device. FIG. 2 is a drawing showing an example of a group 3 nitride semiconductor light-emitting device according to the present disclosure. FIG. 3 is a drawing showing an example of a semiconductor light-emitting structure according to the present disclosure. FIG. 4 is a drawing showing another example of a semiconductor light-emitting structure according to the present disclosure. FIG. 5 is a drawing showing another example of a semiconductor light-emitting structure according to the present disclosure. FIG. 6 is a drawing showing an example of experimental results according to the present disclosure, FIG. 7 is a drawing showing another example of experimental results according to the present disclosure, FIG. 8 is a drawing showing another example of experimental results according to the present disclosure, FIG. 9 is a drawing showing another example of experimental results according to the present disclosure, FIG. 10 is a drawing showing another example of experimental results according to the present disclosure, FIG. 11 is a drawing illustrating a semiconductor light-emitting device related to the present disclosure in terms of bandgap energy, FIGS. 12 and FIGS. 14 are drawings illustrating another example of experimental results according to the present disclosure. FIG. 15 is a diagram comparing the active region of a quantum well structure and the active region of a superlattice structure, FIG. 16 is a diagram showing an example of experimental results according to the semiconductor light-emitting structure presented in Table 7. FIG. 17 is a diagram illustrating various examples of semiconductor light-emitting structures to which a superlattice structure is applied. FIG. 18 is a drawing showing another example of a semiconductor light-emitting structure according to the present disclosure. FIGS. 19 to 21 are drawings illustrating a superlattice region and a lateral growth reinforcement layer, FIG. 22 is a drawing showing another example of a semiconductor light-emitting structure according to the present disclosure. FIGS. 23 to 26 are drawings showing experimental results regarding the examples presented in FIGS. 18 to 22. Specific details for implementing the invention

[0011] The present disclosure will now be described in detail with reference to the accompanying drawings.

[0012] FIG. 2 is a drawing showing an example of a group 3 nitride semiconductor light-emitting device according to the present disclosure, wherein the semiconductor light-emitting device comprises a growth substrate (10), a buffer region (20), an n-side contact region (30), a superlattice region (31), a semiconductor light-emitting structure or active region (42), an electron blocking layer (51; EBL), a p-side contact region (52), a current diffusion electrode (60), a first electrode (70), and a second electrode (80).

[0013] The growth substrate (10) may be a sapphire substrate, a Si (111) substrate, etc., and in particular, a patterned C-face sapphire substrate (C-face PSS) may be applied, and is not particularly limited to homogeneous substrates or heterogeneous substrates.

[0014] The buffer region (20) may be made of un-doped GaN formed on the seed layer, and growth conditions (based on the MOVCD method) may include a temperature of 950°C to 1100°C, a thickness of 1 to 4 μm, a pressure of 100 to 400 mbar, and an H2 atmosphere.

[0015] The n-side contact region (30) may be made of Si-doped GaN, and growth conditions may include a temperature of 1000°C to 1100°C, a thickness of 1 to 4 μm, a pressure of 100 to 400 mbar, and an H2 atmosphere.

[0016] The superlattice region (31) is formed using general growth conditions to enhance current diffusion In a Ga 1-a N / In b Ga 1-b N (0 <a<1, 0≤b<1, a> b) is a stacked superlattice structure (15 cycles), and while the addition of Al is not excluded, it can be doped with an n-type dopant (e.g., Si), and the composition may change slightly during the repetition process.

[0017] The electron blocking layer (51) may be made of Mg-doped AlGaN, and growth conditions may include a temperature of 900°C, a thickness of 10 to 40 nm, a pressure of 50 to 100 mbar, and an H2 atmosphere.

[0018] The p-side contact region (52) can also be formed of Mg-doped GaN using general growth conditions.

[0019] A transparent conductive oxide (TCO), such as ITO, can be used as the current diffusion electrode (60), but is not limited thereto.

[0020] Cr / Ni / Au can be used as the first electrode (70) and the second electrode (80).

[0021] The structure used in the example presented in Fig. 2 is a very common structure conventionally used to make semiconductor light-emitting devices that emit blue and green light using group 3 nitride semiconductors, and any structure used for group 3 nitride semiconductor light-emitting devices that emit blue and green light can be used without special limitations. Although the presented form is a lateral chip form, it goes without saying that flip-chip and vertical chip forms can also be used.

[0022] FIG. 3 is a diagram showing an example of a semiconductor light-emitting structure according to the present disclosure, where FIG. 3(a) shows a conventional green light-emitting group 3 nitride semiconductor light-emitting structure and FIG. 3(b) shows a group 3 nitride semiconductor light-emitting structure according to the present disclosure. For the purpose of explanation, two quantum wells are shown.

[0023] The semiconductor light-emitting structure presented in Fig. 3(a) is In c Ga 1-c N-based quantum well (QW) and Al d Ga e In 1-d-e A barrier layer (barrier) made of N (0≤d≤1, 0≤e≤1; e.g., GaN) is used. The content of In c can vary depending on the peak wavelength at which the semiconductor light-emitting structure emits light; when emitting blue light, c can have a value of 0.1, and when emitting green light, c can have a value of 0.2. InGaN, AlGaN, AlGaInN, etc. can be used as the barrier layer, but GaN is generally used.

[0024] The semiconductor light-emitting structure according to the present disclosure demonstrates that long-wavelength light can be emitted by introducing a barrier layer structure as illustrated in FIG. 3(b) to the semiconductor light-emitting structure presented in FIG. 3(a), which is already commercially available and stably implemented. Therefore, by utilizing the semiconductor light-emitting structure according to the present disclosure, problems associated with using the InGaN active region containing a large amount of In presented in FIG. 1 can be overcome, and problems that occurred during the driving process of the manufactured semiconductor light-emitting device can also be overcome.

[0025] 1st(x), 2nd(x) 1st(x), 2nd(o) 1st(o), 2nd(x) 1st(o), 2nd(o) Wavelength (Wp, nm) 530 (Green) 560 580 625 (Red) Light intensity (qualitative evaluation) Brightness weakness commonly commonly

[0026] As shown in Table 1, it was confirmed that ① when both the first layer (1) and the second layer (2) according to the present disclosure were not provided on both sides of the quantum well, light of a wavelength of 530 nm was emitted brightly; ② when only the second layer (2) according to the present disclosure was provided on the quantum well, light of a wavelength of 560 nm was emitted weakly; ③ when only the first layer (1) according to the present disclosure was provided on the quantum well, light of a wavelength of 580 nm was emitted normally; and ④ when both the first layer (1) and the second layer (2) according to the present disclosure were provided on both sides of the quantum well, light of a wavelength of 625 nm was emitted normally.

[0027] FIG. 4 is a diagram illustrating another example of a semiconductor light-emitting structure according to the present disclosure, where FIG. 4(a) shows an example in which the distribution of In is supplied uniformly during the formation of a quantum well, and FIG. 4(b) shows an example in which the distribution of In is supplied in a graded manner (decreasing and then increasing) during the formation of a quantum well. When the same total amount of In was supplied to each quantum well, the example presented in FIG. 4(b) showed brighter light.

[0028] FIG. 5 is a diagram showing another example of a semiconductor light-emitting structure according to the present disclosure. It was confirmed that the emission wavelength of the semiconductor light-emitting structure can be extended by changing the material composition of the last barrier (the barrier located closest to the p-side in the semiconductor light-emitting structure) from GaN to a material having a lower bandgap energy than GaN (e.g., InGaN). For example, when the ratio of In / (In+Ga) was appropriately adjusted (e.g., 0.05, 0.10; where the ratio is the ratio of the number of molecules between MO sources (TEGa(TriEthyl Ga), TMIn(TriMethyl In), TMAl(TriMethyl Al)) in the gaseous state during growth), it was confirmed that the semiconductor light-emitting structure emitting a wavelength of 625 nm was changed to a semiconductor light-emitting structure emitting a wavelength of 635 nm.

[0029] FIG. 6 is a drawing showing an example of experimental results according to the present disclosure, wherein the first layer (1) and the second layer (2) are both absent in the upper left (green), the second layer (2) is present only in the upper middle (yellow), the first layer (1) is present only in the upper right (orange), the first layer (1) and the second layer (2) are both present in the lower left (red), the example presented in FIG. 5 in the lower middle (more red), and the first layer (1) and the second layer (2) have an Al / (Al+Ga) ratio of 0.95 in the lower right. f Ga 1-f The case where N was used (blue) is shown.

[0030] In the experiment, a GaN barrier layer (4 nm) and In with an In / (In+Ga) ratio of 0.56 were used. c Ga 1-c An N well layer (2.5 nm) was used, specifically using two quantum wells, and a GaN barrier layer (4 nm)-In c Ga 1-c N well layer (2.5 nm) - GaN barrier layer (4 nm) - In c Ga 1-cAn N-well layer (2.5 nm) and a GaN barrier layer (8 nm) were used as the conventional structure. Due to experimental constraints, 1 to 4 quantum wells were used, and there was no significant change in optical properties. For the first layer (1) and the second layer (2), Al with an Al / (Al+Ga) ratio of 0.85 was used. f Ga 1-f N(2nm) was used.

[0031] The well layer (quantum well) was grown to a thickness of 2.5 nm using TMGa and TMIn at a temperature of 670°C, and the barrier layer was grown to a thickness of 4 nm using GaN at a temperature of 770°C. The first layer (1) located first on the n-side was formed immediately after the growth of the first barrier layer (the first barrier layer located on the n-side), using TMAl and TMGa under the same conditions as the first barrier layer, with an Al / (Al+Ga) ratio of 0.85. f Ga 1-f N was grown to a thickness of about 2 nm (these integrally form a barrier layer). Immediately after the growth of the first quantum well (the first well layer located on the n-side), the second layer (2) located on the n-side was grown to a thickness of 0.3 nm using TMGa and TMAl while raising the temperature for 50 seconds, and subsequently, the remaining 1.7 nm was grown under the same growth conditions as the barrier layer, and the GaN barrier layer was grown. The first layer (1) and the second layer (2) located on the p-side were also grown in the same manner, and when both the first layer (1) and the second layer (2) are present, the semiconductor light-emitting structure (42) consists of the last GaN (1.5 nm) - GaN barrier layer (4 nm) - Al of the superlattice region (31). f Ga 1-f N(2nm) 1st layer(1)-In c Ga 1-c N well layer (2.5 nm)-Al f Ga 1-f N (2nm) 2nd layer (2) - GaN barrier layer (4nm) - A f Ga 1-f N(2nm) 1st layer(1)-In c Ga 1-cN well layer (2.5 nm)-Al f Ga 1-f It has a structure of N (2nm) second layer (2) - GaN barrier layer (8nm) - electron blocking layer (51). In the case of the semiconductor light-emitting structure shown in FIG. 5, the last barrier layer (barrier layer adjacent to the electron blocking layer (51)) is In g Ga 1-g It can have a structure of an N barrier layer (4nm) and a GaN barrier layer (4nm).

[0032] As illustrated in FIG. 6, it can be seen that the emission wavelength can be shifted toward a longer direction by introducing a first layer (1) and / or a second layer (2) in a given semiconductor light-emitting structure. However, as shown in the bottom right of FIG. 6, it was found that when the Al concentration of the first layer (1) and the second layer (2) passes a critical point, the wavelength shifts toward a shorter direction than the wavelength at which the original semiconductor light-emitting structure emitted.

[0033] Table 2 summarizes an example of the growth conditions of the superlattice region (31) that was previously used. As previously mentioned, in this disclosure, the composition is expressed as the ratio of the number of molecules between MO sources (TEGa (TriEthyl Ga), TMIn (TriMethyl In), TMAl (TriMethyl Al)) in the gaseous state during growth.

[0034] Growth temperature furtherance thickness In a Ga 1-a N (super lattice region (31)) 720℃ In / (In+Ga) = 0.55 1.5nm In b Ga 1-b N (super lattice region (31)) 780℃ b = 0 (GaN) 1.5nm

[0035] Here, the superlattice region (31) can be doped, and can be doped entirely or partially. For example, In, which is a barrier layer b Ga 1-b N (superlattice region (31)) only 5x10 18 / cm 3 It is possible to dope Si to a certain degree, dope only the even-numbered barrier layers, or dope only the odd-numbered barrier layers.

[0036] Table 3 summarizes an example of the growth conditions for a semiconductor light-emitting structure or active region (42) that was previously used.

[0037] Growth temperature furtherance thickness Al d Ga e In 1-d-e N barrier layer (semiconductor light-emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 4nm In c Ga 1-c N well layer (semiconductor light-emitting structure (42)) 670℃ In / (In+Ga) = 0.56 2.5nm Al d Ga e In 1-d-e N barrier layer (semiconductor light-emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 4nm In c Ga 1-c N well layer (semiconductor light-emitting structure (42)) 670℃ In / (In+Ga) = 0.56 2.5nm Al d Ga e In 1-d-e N barrier layer (semiconductor light-emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 8nm

[0038] Table 4 summarizes an example of growth conditions used for a semiconductor light-emitting structure or active region (42) according to the present disclosure.

[0039] Growth temperature furtherance thickness Al d Ga e In 1-d-e N barrier layer (semiconductor light-emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 4nm Al f Ga 1-f N 1st layer (1) 770℃ Al / (Al+Ga) = 0.85 2nm In c Ga 1-c N well layer (semiconductor light-emitting structure (42)) 670℃ In / (In+Ga) = 0.56 2.5nm Al f Ga 1-f N 2nd layer (2) 770℃ Al / (Al+Ga) = 0.85 2nm Al d Ga e In 1-d-e N barrier layer (semiconductor light-emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 4nm Al f Ga 1-f N 1st layer (2) 770℃ Al / (Al+Ga) = 0.85 2nm In c Ga 1-c N well layer (semiconductor light-emitting structure (42)) 670℃ In / (In+Ga) = 0.56 2.5nm Al f Ga 1-f N 2nd layer (2) 770℃ Al / (Al+Ga) = 0.85 2nm Al d Ga e In 1-d-e N barrier layer (semiconductor light-emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 8nm

[0040] Table 5 summarizes an example of the growth conditions used for the semiconductor light-emitting structure or active region (42) according to Figure 5.

[0041] Growth temperature furtherance thickness Al d Ga e In 1-d-e N barrier layer (semiconductor light-emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 4nm Al f Ga 1-f N 1st layer (1) 770℃ Al / (Al+Ga) = 0.85 2nm In c Ga 1-c N well layer (semiconductor light-emitting structure (42)) 670℃ In / (In+Ga) = 0.56 2.5nm Al f Ga 1-f N 2nd layer (2) 770℃ Al / (Al+Ga) = 0.85 2nm Al d Ga e In 1-d-e N barrier layer (semiconductor light-emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 4nm Al f Ga 1-f N 1st layer (2) 770℃ Al / (Al+Ga) = 0.85 2nm In c Ga 1-c N well layer (semiconductor light-emitting structure (42)) 670℃ In / (In+Ga) = 0.56 2.5nm Al f Ga 1-f N 2nd layer (2) 770℃ Al / (Al+Ga) = 0.85 2nm In g Ga 1-g N barrier layer (semiconductor light-emitting structure (42)) 770℃ In / (In+Ga) = 0.01 4nm Al d Ga e In 1-d-e N barrier layer (semiconductor light-emitting structure (42 770℃ d = 0, e = 1 (GaN) 4nm

[0042] Figure 7 is a diagram showing another example of experimental results according to the present disclosure, illustrating the change in emission wavelength according to the composition of Al. On the left, emission (yellow) was shown when the ratio of Al / (Al+Ga) was 0.25; in the middle, emission (red) was shown when the ratio of Al / (Al+Ga) was 0.75; and on the right, emission (blue) was shown when the ratio of Al / (Al+Ga) was 0.95. Based on the semiconductor emission structure used in the experiment of Figure 6, a significant change in wavelength was induced when the Al composition was 20% or more, and it can be seen that at a certain value of Al 90% or more, the wavelength showed a change of becoming shorter again.

[0043] FIG. 8 is a drawing showing another example of experimental results according to the present disclosure, showing the change in light intensity according to the change in thickness of the first layer (1) and the second layer (2). When using the structure presented in FIG. 6, it can be seen that the maximum value is observed around 2 nm, and the value drops sharply when it reaches 5 nm, and a value of 0.5-4 nm can be used.

[0044] FIG. 9 is a diagram showing another example of experimental results according to the present disclosure, showing the result value when using the semiconductor light-emitting structure presented in FIG. 4(a) on the left and the result value when using the semiconductor light-emitting structure presented in FIG. 4(b) on the right. It can be seen that the example on the right is brighter and has a redder light.

[0045] FIG. 10 is a figure showing another example of experimental results according to the present disclosure, in which the degree of wavelength change according to current was verified. Unlike conventional InGaN red LEDs using a large amount of In (where the wavelength shortens rapidly as the current increases), it can be seen that the wavelength shift is small even when the current increases.

[0046] FIG. 11 is a drawing illustrating a semiconductor light-emitting device related to the present disclosure in terms of bandgap energy, wherein (a) shows a conventional semiconductor light-emitting device, (b) shows a semiconductor light-emitting device presented in FIG. 2, and (c) shows a semiconductor light-emitting device in which a barrier layer form of a semiconductor light-emitting structure (42) is applied to a superlattice region (31) in the structure presented in (b).

[0047] Table 6 summarizes an example of the growth conditions used for the semiconductor light-emitting device presented in Fig. 11(c).

[0048] Growth temperature furtherance thickness Al g Ga 1-g N 3rd floor (3) 780℃ Al / (Al+Ga) = 0.50 0.8nm In a Ga 1-a N (super lattice region (31)) 720℃ In / (In+Ga) = 0.55 1.5nm Al g Ga 1-g N 4th layer (4)) 780℃ Al / (Al+Ga) = 0.50 0.8nm In b Ga 1-b N (super lattice region (31)) 780℃ b = 0 (GaN) 1.5nm : : : : <<15th Period>> : : : : Al g Ga 1-g N 3rd floor (3) 780℃ Al / (Al+Ga) = 0.50 0.8nm In a Ga 1-a N (super lattice region (31)) 720℃ In / (In+Ga) = 0.55 1.5nm Al g Ga 1-g N 4th layer (4)) 780℃ Al / (Al+Ga) = 0.50 0.8nm In b Ga 1-b N (super lattice region (31)) 780℃ b = 0 (GaN) 1.5nm Al d Ga e In 1-d-e N barrier layer (semiconductor light-emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 4nm Al f Ga 1-f N 1st layer (1) 770℃ Al / (Al+Ga) = 0.85 2nm In c Ga 1-c N well layer (semiconductor light-emitting structure (42)) 670℃ In / (In+Ga) = 0.56 2.5nm Al f Ga 1-f N 2nd layer (2) 770℃ Al / (Al+Ga) = 0.85 2nm Al d Ga e In 1-d-e N barrier layer (semiconductor light-emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 4nm Al f Ga 1-f N 1st layer (2) 770℃ Al / (Al+Ga) = 0.85 2nm In c Ga 1-c N well layer (semiconductor light-emitting structure (42)) 670℃ In / (In+Ga) = 0.56 2.5nm Al f Ga 1-f N 2nd layer (2) 770℃ Al / (Al+Ga) = 0.85 2nm Al d Ga e In 1-d-e N barrier layer (semiconductor light-emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 8nm

[0049] FIGS. 12 and FIGS. 14 are drawings showing another example of experimental results according to the present disclosure. FIG. 12 is a drawing showing experimental results for the semiconductor light-emitting device presented in FIG. 11(c), and is the result when all growth conditions are kept the same except for the superlattice region (31) in the semiconductor light-emitting device presented in FIG. 11(b), and shows a result where the wavelength shifts again to a shorter wavelength, similar to the device presented on the right side of FIG. 7. This is because the superlattice region (31) presented in FIG. 11(c), that is, the third layer (3) and fourth layer (4) structure introduced in the superlattice region (31), is judged to play a role in increasing the amount of In injected into the well layer of the semiconductor light-emitting structure (42). Here, when the ratio of Al / (Al+Ga) used in the first layer (1) and the second layer (2) was lowered from 0.85 to 0.45, it was confirmed that red light (emission wavelength of 635 nm) was emitted more than twice as much as the semiconductor light-emitting device shown in Fig. 11(b), as shown in Fig. 13. Fig. 14 shows the PL measurement results of the superlattice region (31) with and without the third layer (3) and the fourth layer (4), and shows that when the third layer (3) and the fourth layer (4) are provided, the PL peak shifts significantly from 445 nm to 535 nm on the long wavelength side.

[0050] Table 7 shows an example of growth conditions in which the active region (42) of the quantum well structure in the semiconductor light-emitting device presented in FIG. 11(c) is changed to a semiconductor light-emitting region or active region (42) of the superlattice structure, similar to the superlattice region (31). FIG. 15 is a diagram comparing the active region of the quantum well structure and the active region of the superlattice structure. In the active region of the quantum well structure shown on the left, each quantum well forms an isolated band due to a thick barrier layer and emits light independently through electron-hole recombination, but in the active region of the superlattice structure shown on the right, that is, when the barrier layer becomes sufficiently thin, each well is not isolated and forms a miniband and emits light through a miniband transition. Although the active region of the superlattice structure is a technique not generally used in group III nitride-based semiconductor light-emitting devices, it has been found to be very effective when applied to the semiconductor light-emitting structure according to the present disclosure (see FIG. 16). The active region (42) was configured identically to the superlattice region (31), except that 8 periods were applied, no doping was performed, the growth temperature of the well layer was set to 700°C, the growth temperature of the remaining layers was set to 780°C, the thickness of the first layer (1) and the second layer (2) was set to 0.8 nm, and Al d Ga e In 1-d-e The thickness of the N barrier layer (d = 0, e = 1 (GaN)) was set to 1.5 nm, the ratio of In / (In+Ga) of the well layer was set to 0.55, the ratio of Al / (Al+Ga) of the first layer (1) and the second layer (2) was set to 0.50, and the thickness of the well layer was set to 1.5 nm.

[0051] Growth temperature furtherance thickness Al g Ga 1-g N 3rd floor (3) 780℃ Al / (Al+Ga) = 0.50 0.8nm In a Ga 1-a N (super lattice region (31)) 720℃ In / (In+Ga) = 0.55 1.5nm Al g Ga 1-g N 4th layer (4)) 780℃ Al / (Al+Ga) = 0.50 0.8nm In b Ga 1-b N (super lattice region (31)) 780℃ b = 0 (GaN) 1.5nm : : : : <<15th Period>> : : : : Al g Ga 1-g N 3rd floor (3) 780℃ Al / (Al+Ga) = 0.50 0.8nm In a Ga 1-a N (super lattice region (31)) 720℃ In / (In+Ga) = 0.55 1.5nm Al g Ga 1-g N 4th layer (4)) 780℃ Al / (Al+Ga) = 0.50 0.8nm In b Ga 1-b N (super lattice region (31)) 780℃ b = 0 (GaN) 1.5nm Al d Ga e In 1-d-e N barrier layer (semiconductor light-emitting structure (42)) 780℃ d = 0, e = 1 (GaN) 4nm Al f Ga 1-f N 1st layer (1) 780℃ Al / (Al+Ga) = 0.50 0.8nm In c Ga 1-c N well layer (semiconductor light-emitting structure (42)) 700℃ In / (In+Ga) = 0.55 1.5nm Al f Ga 1-f N 2nd layer (2) 780℃ Al / (Al+Ga) = 0.50 0.8nm Al d Ga e In 1-d-e N barrier layer (semiconductor light-emitting structure (42)) 780℃ d = 0, e = 1 (GaN) 1.5nm : : : : <<8th Period>> : : : : Al f Ga 1-f N 1st layer (1) 780℃ Al / (Al+Ga) = 0.50 0.8nm In c Ga 1-c N well layer (semiconductor light-emitting structure (42)) 700℃ In / (In+Ga) = 0.55 1.5nm Al f Ga 1-f N 2nd layer (2) 780℃ Al / (Al+Ga) = 0.50 0.8nm Al d Ga e In 1-d-e N barrier layer (semiconductor light-emitting structure (42)) 780℃ d = 0, e = 1 (GaN) 8nm

[0052] Figure 16 is a diagram showing an example of experimental results according to the semiconductor light-emitting structure presented in Table 7, and it was confirmed that there was a 7-fold increase in output compared to the example presented in Table 6.

[0053] FIG. 17 is a diagram illustrating various examples of semiconductor light-emitting structures with a superlattice structure applied. (a) shows a semiconductor light-emitting device presented in Table 7 in terms of bandgap energy, and (b) shows a semiconductor light-emitting device in which the layers located on the p-side of the superlattice region (31) and the semiconductor light-emitting structure (42), namely the second layer (2) and the fourth layer (4), have been removed. The semiconductor light-emitting device presented in FIG. 17(b) also showed experimental results similar to those of the semiconductor light-emitting device presented in FIG. 17(a). Although the growth conditions were all the same, the ratio of Al / (Al+Ga) of the first layer (1) was changed from 0.50 to 0.65.

[0054] Meanwhile, in the semiconductor light-emitting device shown in FIG. 17(b), the Al of the semiconductor light-emitting structure (42) d Ga e In 1-d-e When the thickness of the N barrier layer (d = 0, e = 1 (GaN)) was changed from 1.5 nm to 1 nm, the emission wavelength shifted to the longer wavelength side from 630 nm to 640 nm.

[0055] In addition, in the semiconductor light-emitting device shown in FIG. 17(b), when the repetition period of the semiconductor light-emitting structure (42) was changed from 8 periods to 16 periods, the light emission wavelength was shortened to 625 nm, and the amount of light was similar.

[0056] In addition, in the semiconductor light-emitting device shown in FIG. 17(b), the Al of the semiconductor light-emitting structure (42) d Ga e In 1-d-eWhen the thickness of the N barrier layer (d = 0, e = 1 (GaN)) was changed from 1.5 nm to 0.75 nm, the thickness of the first layer (1) was changed from 0.8 nm to 0.4 nm, and the thickness of the well layer was reduced from 1.5 nm to 0.75 nm, the wavelength decreased from 630 nm to 600 nm, and the amount of light decreased by more than 50%.

[0057] In addition, in the semiconductor light-emitting device shown in FIG. 17(b), the Al of the semiconductor light-emitting structure (42) d Ga e In 1-d-e When the thickness of the N barrier layer (d = 0, e = 1 (GaN)) was changed from 1.5 nm to 1.0 nm, the thickness of the first layer (1) was kept at 0.8 nm, and the thickness of the well layer was increased from 1.5 nm to 2.0 nm, the wavelength increased significantly from 630 nm to 680 nm, and the amount of light decreased by about 50%. Under these conditions, by changing the growth temperature to a higher level, the emission wavelength could be made to 630 nm, and the amount of light increased by 20% compared to the semiconductor light-emitting device shown in FIG. 17(b).

[0058] Of course, it is possible to make changes such as adding dopants to each layer constituting the superlattice region (31) and the semiconductor light-emitting structure (42), adding Al, In, or Ga, or slightly changing the composition and growth conditions during the repetition process.

[0059] FIG. 18 is a drawing showing another example of a semiconductor light-emitting structure according to the present disclosure, which differs from the semiconductor light-emitting structure shown in FIG. 2 in that it has a plurality of superlattice regions (33, 34, 35), and in the example shown, an active region (42) of the superlattice structure is used. A lateral growth enhancement layer (36) is provided between the superlattice region (33) and the superlattice region (34), and a lateral growth recovery layer (37) is provided between the superlattice region (34) and the superlattice region (35).

[0060] The superlattice region (33, 34, 35) may be composed of sequential iterative stacking of AlGaN-InGaN-GaN, sequential iterative stacking of GaN-InGaN-AlGaN, sequential iterative stacking of GaN-AlGaN-InGaN-AlGaN, or sequential iterative stacking of AlGaN-InGaN, and it is sufficient that an AlGaN-InGaN interface exists within the superlattice region (33, 34, 35), and AlInGaN is made to exist by forming an AlGaN-InGaN interface, whether by diffusion or intentionally. In conventional group 3 nitride semiconductor light-emitting devices, the superlattice region is mainly used to reduce the energy bandgap difference between the n-side contact region (30; e.g., GaN) and the active region containing InGaN, but in the present disclosure, the superlattice region (33, 34, 35) is used to allow a large amount of In to enter the active region (42) in addition to this function. That is, since the difference in lattice constants between GaN and InGaN is large, In does not enter the active region well, but by increasing the In content through the superlattice regions (33, 34, 35), In can be introduced more efficiently into the active region (42). For reference, as In is introduced into the superlattice region (33), more In can be introduced into the superlattice region (34) even if the same growth conditions as the superlattice region (33) are used, and the same applies to the superlattice region (35).

[0061] The superlattice regions (33, 34, 35) formed in this way do not have a flat surface due to the AlGaN-InGaN interface, but rather have a rough surface (S) as shown in FIGS. 19 to 21. Since the continuous accumulation of the rough surface (S) of the superlattice region (33) can increase crystal defects in the device, a side growth reinforcement layer (36) is introduced to perform a flattening process, and a superlattice region (34) is introduced again to facilitate the injection of In into the active region (42), while a side growth reinforcement layer (37) is introduced once more to resolve crystal defects. There may be one or more superlattice regions (33, 34, 35), and there is no limit to the upper limit. However, as shown in FIG. 21, it is more preferable not to introduce a side growth reinforcement layer between the active region (42) and the superlattice region (35) closest thereto. The rough surface (S) is composed of a semi-polar surface. For example, when the growth substrate (10) is a C-plane sapphire substrate, the flat group III nitride semiconductor grown thereon has a polar surface grown along the c-axis, but the three-dimensional surface constituting the rough surface (S) is composed of a semi-polar surface. In the case of a polar surface, the injection of In is easy, but it has the disadvantage of a large piezo-constant (when the piezo-constant is large, the wavelength may shift significantly toward the short wavelength as the current density increases), and in the case of a non-polar surface, the piezo-constant is 0, but it has the disadvantage of being difficult to inject In. In the present disclosure, by growing an active region (42) on the rough surface (S), that is, the semi-polar surface, the injection of In is made easy, while having an appropriate piezo-constant. As shown in FIG. 21, the last barrier layer of the active area (42), i.e., the last barrier (44), may be grown flat by adjusting the growth conditions, or it may be grown to have a shape that follows a rough surface (S).

[0062] Table 8 shows an example of the growth conditions for the semiconductor light-emitting structure presented in Fig. 18.

[0063] Growth temperature (°C) furtherance Thickness (nm) GaN (super lattice region (33)) 830 1.5 In x Ga 1-x N(superlattice region (33)) 730 x=0.1 1.5 Al y Ga 1-y N(superlattice region (33)) 780 y=0.5 0.5 : : : : <<10th Period>> : : : : GaN (lateral growth reinforcement layer (36)) 830 100 GaN (super lattice region (34)) 830 1.5 In x Ga 1-x N(superlattice region (34)) 730 x=0.1 1.5 Al y Ga 1-y N(superlattice region (34)) 780 y=0.5 0.5 : : : : <<10th Period>> : : : : GaN (lateral growth reinforcement layer (37)) 830 100 Al y Ga 1-y N(superlattice region (35)) 780 y=0.5 0.5 In x Ga 1-x N(superlattice region (35)) 730 x=0.1 1.5 GaN (super lattice region (35)) 830 1.5 : : : : <<10th Anniversary>> : : : : In x Ga 1-x N (active area (42)) 710 x=0.35 2.2 In x Ga 1-x N (active area (42)) 760 x=0.05 0.4 Al y Ga 1-y N (active area (42)) 760 y=0.1 0.8 In x Ga 1-x N (active area (42)) 760 x=0.05 0.4 : 3rd Anniversary : Al y Ga 1-y N(Last barrier (44))GaN(Last barrier (44))In x Ga 1-x N(Last barrier (44)) 760760760 y=0.05x=0.05 666 Al y Ga 1-x-y In x N (electronic blocking layer (51)) 820 x=0.1,y=0.2 20 p-GaN (p-side contact region (52)) 900 200

[0064] The thickness of the lateral growth reinforcement layer (36, 37) is sufficient to be grown to cover the rough surface (S), and there is no upper limit thereto, but if it becomes too thick (e.g., 500 nm), the thick GaN layer is located before the active region (42), and there is a concern that the function of the superlattice region (33, 34) will be significantly reduced.

[0065] Here, unlike the previous examples, the compositions of In, Al, and Ga used were predicted values ​​in the solid state after growth was complete. For reference, the same In x Ga 1-x Even if N (x=0.1), the actual indium content can increase as growth progresses, and it must be taken into account that more In can be included as the thickness of InGaN increases and growth progresses.

[0066] Last barrier (44) is Al y Ga 1-y N(44; y=0.05), GaN(44), In x Ga 1-x I tried each of N(44; x=0.05), and Al y Ga 1-y The best light output was observed when N (44; y=0.05). Additionally, in general LED devices, adding Al to the last barrier (44) results in a short wavelength shift, while adding In results in a long wavelength shift; however, in the device presented in this example, adding Al resulted in a long wavelength shift, and adding In resulted in a short wavelength shift. It can be seen that the desired red light wavelength can be obtained by controlling the content of Al and In, utilizing behavior opposite to conventional understanding, which is presumed to be a strain effect. In the active region (42) presented in Table 8, the last In of the 3rd period 0.05 Ga 0.95N(0.4nm)-Al 0.1 Ga 0.9 N(0.8nm)-In 0.05 Ga 0.95 Omit N(0.4nm), and Al 0.05 Ga 0.95 N (last barrier (44)); 6nm), GaN (last barrier (44); 6nm) or In x Ga 1-x It is also possible to form N (last barrier (44); 6nm), and the last barrier (44) In 0.05 Ga 0.95 N(0.4nm)-Al 0.1 Ga 0.9 N(0.8nm)-In 0.05 Ga 0.95 N(0.4nm)-Al 0.05 Ga 0.95 Compared to configuring with N(6nm), Al 0.05 Ga 0.95 The effect was good when composed solely of N(6nm), and In 0.05 Ga 0.95 N(0.4nm)-Al 0.1 Ga 0.9 N(0.8nm)-In 0.05 Ga 0.95 N(0.4nm)-In 0.05 Ga 0.95 When composed of N(6nm), In 0.05 Ga 0.95 The effect was better than when composed solely of N(6nm), and Al 0.05 Ga 0.95 The side using N(6nm) is In 0.05 Ga 0.95 The effect was better than when using N (6nm) and GaN (6nm) (see Fig. 23).

[0067] In, which is a region corresponding to a well layer within an active region (42) (although the presented example shows an active region (42) having a superlattice structure forming a mini-band, for convenience, the expressions 'well layer' and 'barrier layer' used in quantum well structures are used as they are) x Ga1-x Region In in which the thickness (2.2 nm) of N (active region (42); x=0.35) corresponds to the barrier layer x Ga 1-x N(active region(42); x=0.05)-Al y Ga 1-y N(active region(42); y=0.1)-In x Ga 1-x It has the characteristic of being thicker than the thickness (1.6 nm = 0.4 nm + 0.8 nm + 0.4 nm) of N (active region (42); x = 0.05). It was also confirmed that in the active region (42), the thinner the thickness of the barrier layer and the thicker the thickness of the well layer, the longer the wavelength changes (see FIG. 24).

[0068] In addition, as shown, an increase in efficiency was demonstrated by using an InGaN-AlGaN-InGaN type barrier layer instead of a single GaN barrier (see Fig. 25).

[0069] In addition, after the growth of the last barrier (44), when the electron blocking layer (51) was grown with AlInGaN instead of AlGaN, it showed an effect of increasing efficiency by 10% as it moved to a long wavelength (see FIG. 26).

[0070] FIG. 22 is a drawing showing another example of a semiconductor light-emitting structure according to the present disclosure, in which, unlike the semiconductor light-emitting device shown in FIG. 18, the superlattice region (33, 34) is replaced by a strain control region (38, 39). Generally, a superlattice structure refers to a structure in which two or more layers having different band gaps are grown alternately, each having a thickness of several nanometers, and tunneling occurs to form a miniband.

[0071] Table 9 shows an example of the growth conditions for the semiconductor light-emitting structure presented in Figure 18.

[0072] Growth temperature (°C) furtherance Thickness (nm) GaN (region (38)) 870 15 In x Ga 1-x N(superlattice region (38)) 770 x=0.05 30 Al y Ga 1-y N(superlattice region (38)) 870 y=0.2 5 : : : : <<10th Period>> : : : : GaN (lateral growth reinforcement layer (36)) 1000 45 GaN (super lattice region (39)) 870 15 In x Ga 1-x N(superlattice region (39)) 770 x=0.05 30 Al y Ga 1-y N(superlattice region (39)) 870 y=0.2 5 : : : : <<10th Period>> : : : : GaN (lateral growth reinforcement layer (37)) 1000 45 Al y Ga 1-y N(superlattice region (35)) 780 y=0.5 0.5 In x Ga 1-x N(superlattice region (35)) 730 x=0.1 1.5 GaN (super lattice region (35)) 830 1.5 : : : : <<10th Anniversary>> : : : : In x Ga 1-x N (active area (42)) 710 x=0.35 2.2 In x Ga 1-x N (active area (42)) 760 x=0.05 0.4 Al y Ga 1-y N (active area (42)) 760 y=0.1 0.8 In x Ga 1-x N (active area (42)) 760 x=0.05 0.4 : 3rd Anniversary : Al y Ga 1-y N(Last barrier (44))GaN(Last barrier (44))In x Ga 1-x N(Last barrier (44)) 760760760 y=0.05x=0.05 666 Al y Ga 1-x-y In x N (electronic blocking layer (51)) 820 x=0.1,y=0.2 20 p-GaN (p-side contact region (52)) 900 200

[0073] In order to emit red light, a relatively high In content is required in the active region (42). In cases where it is difficult to overcome crystal defects caused by a sharp difference in lattice constants between the n-side semiconductor region (30) and the active region (42) using only the superlattice region, this problem can be resolved by introducing one or more strain control regions (38, 39).

[0074] The strain control region (38, 39) was grown in a hydrogen atmosphere, and the superlattice region (35) and subsequent regions were grown in a nitrogen atmosphere. By growing in a hydrogen atmosphere, the growth rate of the strain control region (38, 39) can be improved.

[0075] In the strain control region (38,39), In x Ga 1-x The thickness of N was set to several tens of nm (e.g., 30 nm), and the composition x was 0 <x<0.3로 둘 수 있고, GaN층은 두께를 10nm~200nm로 둘 수 있으며, Al y Ga 1-y The N-layer is y = 0.01 <y<0.9, 두께는 1~20nm로 둘 수 있다. In x Ga 1-x It is desirable that the growth temperature difference (delta T) between N and GaN differs by at least 20 degrees. The growth temperature of GaN is In x Ga 1-x The growth temperature was set higher than that of N.

[0076] Compared to the example presented in Table 8, the thickness of the lateral growth reinforcing layer (36) is reduced from 100 nm to 45 nm, and the lateral growth reinforcing layer (36) can be formed with a thickness of 50 nm or less when the degree of rough surface (S) is less than that of the example presented in Table 8.

[0077] Various embodiments of the present disclosure are described below.

[0078] (1) A method for manufacturing a group 3 nitride semiconductor light-emitting structure that emits red light with a peak wavelength of 600 nm or more, comprising the step of growing a first superlattice region formed by the repeated stacking of a first sublayer and a second sublayer; A method for manufacturing a group nitride semiconductor light-emitting structure, comprising: a step of growing an active region on a first superlattice region, the active region comprising a third sublayer made of a group nitride semiconductor containing Al and having a first bandgap energy, a fourth sublayer made of a group nitride semiconductor containing In and having a second bandgap energy smaller than the first bandgap energy, and a fifth sublayer made of a group nitride semiconductor containing Al and having a third bandgap energy larger than the second bandgap energy; wherein, in the step of growing the active region, the In content of the fourth sublayer is set so that when the third sublayer and the fifth sublayer are GaN, the fourth sublayer emits light with an emission peak wavelength of 600 nm or less, and the Al content of the third sublayer and the Al content of the fifth sublayer are set so that the fourth sublayer emits red light having an emission peak wavelength of 600 nm or more.

[0079] (2) A method for manufacturing a group 3 nitride semiconductor light-emitting structure, wherein the active region includes a quantum well structure, the fourth sublayer is a quantum well layer, and the third and fifth sublayers are quantum barrier layers. (See FIG. 3)

[0080] (3) A method for manufacturing a group 3 nitride semiconductor light-emitting structure by decreasing and then increasing the supply of In during the growth of the fourth sublayer. (See FIG. 4)

[0081] (4) A method for manufacturing a group 3 nitride semiconductor light-emitting structure, wherein, in the step of establishing an active region, a third sublayer, a fourth sublayer, and a fifth sublayer are grown sequentially multiple times, and the fifth sublayer provided on the uppermost side comprises InGaN to shift the light emission peak wavelength of the entire active region to a long wavelength. (See FIG. 5)

[0082] (5) A method for manufacturing a group 3 nitride semiconductor light-emitting structure in which the fifth sublayer provided on the uppermost side is InGaN-GaN.

[0083] (6) A method for manufacturing a group 3 nitride semiconductor light-emitting structure in which the third sublayer and the fifth sublayer are each made of AlGaN-GaN-AlGaN.

[0084] (7) A method for manufacturing a group 3 nitride semiconductor light-emitting structure, wherein the first sublayer has a fourth bandgap energy and the second sublayer has a fifth bandgap energy greater than the fourth bandgap energy, and the second sublayer is made of AlGaN-(In)GaN, AlGaN-(In)GaN-AlGaN or (In)GaN-AlGaN. (See FIG. 11(c))

[0085] (8) A method for manufacturing a group 3 nitride semiconductor light-emitting structure in which the Al content of the second sublayer AlGaN is greater than the Al content of the third sublayer and the Al content of the fifth sublayer.

[0086] (9) A method for manufacturing a group 3 nitride semiconductor light-emitting structure in which the active region includes a superlattice structure. (See Table 7)

[0087] (10) A method for manufacturing a group 3 nitride semiconductor light-emitting structure in which the third sublayer and the fifth sublayer are GaN-AlGaN. (See FIG. 17(b)) Explanation of the symbols

[0088] 1st layer (1), 2nd layer (2), 3rd layer (3), 4th layer (4), growth substrate (11), buffer region (21), n-side contact region (30), superlattice region (31), semiconductor light-emitting structure (42), electron blocking layer (51; EBL), p-side contact region (52), current diffusion electrode (60), 1st electrode (70), 2nd electrode (80)

Claims

Claim 1 A group 3 nitride semiconductor light-emitting device comprising: an active region emitting red light; and a semipolar region provided below the active region for growing the active region; wherein the active region and the semipolar region are made of a group 3 nitride semiconductor, and the active region and the semipolar region are grown on a growth substrate. Claim 2 A group 3 nitride semiconductor light-emitting device according to claim 1, wherein the active region is grown on a rough surface composed of semipolar panels. Claim 3 A group 3 nitride semiconductor light-emitting device comprising: a superlattice region having a rough surface according to claim 2. Claim 4 In claim 3, the superlattice region is a group 3 nitride semiconductor light-emitting device having an AlGaN-InGaN interface. Claim 5 A group 3 nitride semiconductor light-emitting device comprising: an additional superlattice region below a superlattice region in claim 4. Claim 6 A group 3 nitride semiconductor light-emitting device comprising: a lateral growth strengthening layer between a superlattice region and an additional superlattice region in claim 5. Claim 7 A group 3 nitride semiconductor light-emitting device comprising: a strain control region below a superlattice region in claim 4.

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