KR20240059185A - Method of manufacturing a iii-nitride semiconductor light emitting structure - Google Patents

Abstract

The present disclosure relates to a method of manufacturing a group III nitride semiconductor light-emitting structure that can shift the emission wavelength to a long or short wavelength using selective growth or nanowires.

Description

Method for manufacturing a group III nitride semiconductor light emitting structure {METHOD OF MANUFACTURING A III-NITRIDE SEMICONDUCTOR LIGHT EMITTING STRUCTURE}

This disclosure generally relates to a method of manufacturing a Group III nitride semiconductor light emitting structure, and in particular, to manufacturing a Group III nitride semiconductor light emitting structure that can shift the emission wavelength to a long or short wavelength using selective growth or nanowires. It's about method. Here, the Group 3 nitride semiconductor is made of a compound of Al(x)Ga(y)In(1-x-y)N (0≤x≤1, 0≤y≤1, 0≤x+y≤1).

Here, background information related to the present disclosure is provided, and this does not necessarily mean prior art.

Currently, commercial red light-emitting semiconductor light-emitting devices (e.g. LED, LD) are manufactured using AlGaInP-based compound semiconductors, but recently, yellow ( Those emitting yellow, amber, orange, red, and infrared are being considered.

1 is a diagram showing an example of a conventional red light-emitting group III nitride semiconductor light-emitting device, in which the semiconductor light-emitting device includes a growth substrate 10 (e.g., a patterned C-plane sapphire substrate (PSS)) and a buffer region 20 (e.g., a patterned C-plane sapphire substrate (PSS)). : un-doped GaN (2㎛) formed on the seed layer (gaN grown at low temperature), n-side contact area (30; e.g. Si-doped GaN (2~8㎛) and Si-doped Al _0.03 Ga _0.97 N (1 μm)), superlattice region (31; e.g., 15 cycles of GaN (6 nm)/In _0.08 Ga _0.92 N (2 nm)), 15 nm thick Si-doped GaN (32), the In content is Few quantum well structures (41: e.g. quantum wells of In _0.2 Ga _0.8 N (2 nm) and barrier layer of GaN (2 nm)/Al _0.13 Ga _0.87 N (18 nm)/GaN (3 nm)), red light-emitting active region (42; Example: Quantum well made of InGaN (2.5 nm) - Barrier layer made of AlN (1.2 nm)/GaN (2 nm)/Al _0.13 Ga _0.87 N (18 nm)/GaN (3 nm) - Made of InGaN (2.5 nm) quantum well-barrier layer of AlN (1.2 nm)/GaN (23 nm)), 15 nm thick GaN layer (43), 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).

Additionally, U.S. Patent Publication No. US10,396,240 also proposes a red light-emitting semiconductor light-emitting device using an InGaN active region.

This is described at the end of the ‘specific details for carrying out the invention’.

Here, a general summary of the disclosure is provided, and this should not be construed as limiting the scope of the disclosure (This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features).

According to one aspect of the present disclosure, a method for manufacturing a group III nitride semiconductor light emitting structure is provided.

This is described at the end of the ‘specific details for carrying out the invention’.

1 is a diagram showing an example of a conventional red light-emitting group III nitride semiconductor light-emitting device;
2 is a diagram showing an example of a Group III nitride semiconductor light emitting device according to the present disclosure;
3 is a diagram showing an example of a semiconductor light-emitting structure according to the present disclosure;
4 is a diagram showing another example of a semiconductor light-emitting structure according to the present disclosure;
5 is a diagram showing another example of a semiconductor light-emitting structure according to the present disclosure;
6 is a diagram showing an example of an experiment result according to the present disclosure;
7 is a diagram showing another example of experimental results according to the present disclosure;
8 is a diagram showing another example of experimental results according to the present disclosure;
9 is a diagram showing another example of experimental results according to the present disclosure;
10 is a diagram showing another example of experimental results according to the present disclosure;
11 is a diagram illustrating a semiconductor light emitting device related to the present disclosure from the perspective of bandgap energy;
12 and 14 are diagrams showing another example of experimental results according to the present disclosure;
Figure 15 is a diagram comparing the active area of the quantum well structure and the active area of the superlattice structure;
16 is a diagram showing an example of experimental results according to the semiconductor light emitting structure shown in Table 7;
17 is a diagram illustrating various examples of semiconductor light-emitting structures using a superlattice structure;
18 is a diagram showing another example of a semiconductor light-emitting structure according to the present disclosure;
19 to 21 are views explaining the superlattice region and the laterally grown reinforcement layer;
22 is a diagram showing another example of a semiconductor light-emitting structure according to the present disclosure.
Figures 23 to 26 show experimental results for the examples shown in Figures 18 to 22;
27 is a diagram showing another example of a semiconductor light emitting device according to the present disclosure;
28 is a diagram showing another example of a semiconductor light emitting device according to the present disclosure;
29 is a diagram showing another example of a semiconductor light emitting device according to the present disclosure;
30 is a diagram showing another example of a semiconductor light emitting device according to the present disclosure;
31 is a diagram showing another example of a semiconductor light emitting device according to the present disclosure;
Figure 32 is a diagram showing an example of the opening pattern shown in Figure 31;
33 is a view showing another example of the opening arrangement of the growth prevention film according to the present disclosure;
34 to 36 are diagrams showing an example of a method for manufacturing a semiconductor light emitting device according to the present disclosure;
37 to 40 are diagrams showing another example of a method for manufacturing a semiconductor light emitting device according to the present disclosure;
Figure 41 is a diagram showing an example of experimental results according to the method shown in Figures 27 to 33;
Figure 42 is a diagram showing another example of experimental results according to the method presented in Figures 27 to 33;
Figure 43 is a graph summarizing the experimental results presented in Figures 41 and 42;
44 is a diagram showing an example of the results of a light excitation (PL) experiment according to the present disclosure;
45 is a diagram showing an example of electroluminescence (EL) experiment results according to the present disclosure;
46 is a diagram showing an example of the results of an electroluminescence (EL) experiment with a laser added according to the present disclosure;
47 to 49 are diagrams illustrating the light emission principle according to the present disclosure.

Hereinafter, the present disclosure will now be described in detail with reference to the accompanying drawing(s).

FIG. 2 is a diagram illustrating an example of a Group III nitride semiconductor light emitting device according to the present disclosure, wherein the semiconductor light emitting device includes a growth substrate 10, a buffer region 20, an n-side contact region 30, and 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. Includes.

The growth substrate 10 may be a sapphire substrate, a Si (111) substrate, etc. In particular, a patterned C-face sapphire substrate (C-face PSS) may be used, and there is no particular limitation on the use of a same-type substrate or a heterogeneous substrate.

The buffer region 20 may be made of undoped GaN formed on the seed layer, and the growth conditions (based on MOVCD method) are a temperature of 950°C to 1100°C, a thickness of 1 to 4 μm, a pressure of 100 to 400 mbar, and H ₂ Atmosphere can be used.

The n-side contact region 30 may be made of Si-doped GaN, and growth conditions 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 H ₂ atmosphere.

The superlattice region 31 is In _a Ga _1-a N/In _b Ga _1-b N (0<a<1, 0≤b<1, a>b) using general growth conditions to improve current diffusion. ) is a stacked superlattice structure with a repetition of 15 cycles, and the addition of Al is not excluded, and it can be doped with an n-type dopant (e.g. Si), and the composition may change slightly during the repetition process. am.

The electron blocking layer 51 may be made of Mg-doped AlGaN, and growth conditions include a temperature of 900°C, a thickness of 10 to 40 nm, a pressure of 50 to 100 mbar, and an H ₂ atmosphere.

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

TCO (Tranparent Conductive Oxide) such as ITO may be used as the current diffusion electrode 60, but is not limited thereto.

Cr/Ni/Au may be used as the first electrode 70 and the second electrode 80.

The structure used in the example shown in Figure 2 is a very common structure used to make semiconductor light-emitting devices that emit blue and green light using group III nitride semiconductors. Any structure used in a light emitting device can be used without particular restrictions. Although the presented form is a lateral chip form, it goes without saying that flip chip form and vertical chip form can be used.

FIG. 3 is a diagram showing an example of a semiconductor light-emitting structure according to the present disclosure. FIG. 3(a) shows a conventional green light-emitting Group III nitride semiconductor light-emitting structure, and FIG. 3(b) shows a 3-nitride semiconductor light-emitting structure according to the present disclosure. A nitride semiconductor light emitting structure is presented. For illustration purposes, two quantum wells are presented.

The semiconductor light emitting structure shown in Figure 3(a) is a quantum well (QW) made of In _c Ga _1-c N and Al _d Ga _e In _1-de N (0≤d≤1, 0≤e≤1; e.g. A barrier layer made of GaN is used. The content c of In may vary depending on the peak wavelength at which the semiconductor light emitting structure emits light. When emitting blue light, c may have a value of 0.1, and when emitting green color, c may have a value of 0.2. You can. InGaN, AlGaN, AlGaInN, etc. can be used as the barrier layer, but GaN is generally used.

The semiconductor light-emitting structure according to the present disclosure emits light of a long wavelength by introducing a barrier layer structure as shown in FIG. 3(b) into the semiconductor light-emitting structure shown in FIG. 3(a), which has already been commercialized and stably implemented. It shows that it can be done. Therefore, by utilizing the semiconductor light emitting structure according to the present disclosure, it is possible to overcome the problems when using the InGaN active region containing a large amount of In shown in FIG. 1, and also solve the problems that occurred during the driving process of the manufactured semiconductor light emitting device. can overcome.

1st(x), 2nd(x) 1st(x), 2nd(o) 1st(o), 2nd(x) 1(o), 2(o) Wavelength (Wp, nm) 530 (green) 560 580 625 (red) Light quantity (qualitative evaluation) bright weakness commonly commonly

As shown in Table 1, ① when neither the first layer (1) nor the second layer (2) according to the present disclosure were provided on both sides of the quantum well, light with a wavelength of 530 nm was brightly emitted, and ② the quantum well In the case where only the second layer (2) according to the present disclosure is provided, light with a wavelength of 560 nm is weakly emitted, and ③ when the quantum well is provided with only the first layer (1) according to the present disclosure, light with a wavelength of 580 nm is usually emitted. ④ It was confirmed that light with a wavelength of 625 nm was normally emitted 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.

FIG. 4 is a diagram showing another example of a semiconductor light-emitting structure according to the present disclosure. FIG. 4(a) shows an example in which In is uniformly distributed during the formation of a quantum well, and FIG. 4(b) shows a quantum well. This shows an example in which the distribution of In was supplied to be graded (decreased and then increased) during the formation of a well. When the same total amount of In was supplied to each quantum well, the example shown in Figure 4(b) showed brighter light.

Figure 5 is a diagram showing another example of a semiconductor light-emitting structure according to the present disclosure, in which the material composition of the last barrier (the barrier located closest to the p side in the semiconductor light-emitting structure) is changed from GaN to a material with a lower bandgap energy than GaN ( It was confirmed that by changing to (e.g. InGaN), the emission wavelength of the semiconductor light emitting structure can be made longer. For example, adjust the ratio of In/(In+Ga) appropriately (e.g., 0.05, 0.10; where the ratio is the MO source (TEGa (TriEthyl Ga), TMIn (TriMethyl In), TMAl (TriMethyl Al) in the gas phase during growth). )), it was confirmed that the semiconductor light-emitting structure that emits light at a wavelength of 625 nm was changed to a semiconductor light-emitting structure that emits light at a wavelength of 635 nm.

Figure 6 is a diagram showing an example of an experiment result according to the present disclosure, where both the first layer (1) and the second layer (2) are absent at the top left (green), and the second layer (2) is in the middle of the top. only (yellow), only the first layer (1) on the top right (orange), both the first layer (1) and second layer (2) on the bottom left (red), in the middle of the bottom For the example shown in Figure 5 (more red), at the bottom right, Al _f Ga _1-f N with a ratio of Al/(Al+Ga) of 0.95 is used for the first layer (1) and second layer (2). (blue) is shown.

In the experiment, a GaN barrier layer (4 nm) and an In _c Ga _1-c N well layer (2.5 nm) with an In/(In+Ga) ratio of 0.56 were used. Specifically, two quantum wells were used to form a GaN barrier layer. Layer (4nm) - In _c Ga _1-c N well layer (2.5 nm) - GaN barrier layer (4 nm) - In _c Ga _1-c N well layer (2.5 nm) - GaN barrier layer (8 nm) as the existing structure. It was used. Due to limitations in the experiment, 1 to 4 quantum wells were used, and there was no significant change in optical characteristics. For the first layer (1) and the second layer (2), Al _f Ga _1-f N (2 nm) with an Al/(Al+Ga) ratio of 0.85 was used.

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 is formed using TMAl and TMGa under the same conditions as the first barrier layer immediately after the growth of the first barrier layer (first barrier layer located on the n-side) using Al/( Al _f Ga _1-f N with an Al + Ga) ratio of 0.85 was grown to a thickness of about 2 nm (they collectively 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 s. Afterwards, 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 provided, the semiconductor light emitting structure ( 42) is the last GaN (1.5 nm) of the superlattice region 31 - GaN barrier layer (4 nm) - Al _f Ga _1-f N (2 nm) first layer (1) - In _c Ga _1-c N well layer (2.5nm)-Al _f Ga _1-f N (2nm) second layer (2)-GaN barrier layer (4nm)-A _f Ga _1-f N (2nm) first layer (1)-In _c Ga ₁ It has a structure of _-c N well layer (2.5 nm) - Al _f Ga _{1 - f} N (2 nm) second layer (2) - GaN barrier layer (8 nm) - electron blocking layer (51). In the case of the semiconductor light emitting structure shown in Figure 5, the last barrier layer (barrier layer adjacent to the electron blocking layer 51) may have a structure of In _g Ga _1-g N barrier layer (4 nm) - GaN barrier layer (4 nm). there is.

As shown in FIG. 6, it can be seen that the emission wavelength can be shifted to the longer side by introducing the first layer 1 and/or the second layer 2 in a given semiconductor light emitting structure. However, as shown in the bottom right of FIG. 6, this phenomenon occurs when the Al concentration of the first layer (1) and the second layer (2) passes the critical point, and the wavelength moves to a shorter wavelength than the wavelength at which the original semiconductor light emitting structure emits light. could know that

Table 2 summarizes examples of growth conditions for the previously used superlattice region 31. As described above, in the present disclosure, the composition is expressed as the ratio of the number of molecules between the MO sources (TriEthyl Ga (TEGa), TriMethyl In (TMIn), and TriMethyl Al (TMAl)) in the gas phase during growth.

growth temperature Furtherance thickness In _a Ga _1-a N (superlattice region (31)) 720℃ In/(In+Ga) = 0.55 1.5nm In _b Ga _1-b N (superlattice region (31)) 780℃ b = 0 (GaN) 1.5nm

Here, the superlattice region 31 may be doped, fully doped, or partially doped. For example, only the barrier layer In _b Ga _1-b N (superlattice region 31) may be doped with Si to about 5x10 ¹⁸ /cm ³ , only the even-numbered barrier layers may be doped, or only the odd-numbered barrier layers may be doped. .

Table 3 summarizes examples of growth conditions for the previously used semiconductor light emitting structure or active region 42.

growth temperature Furtherance thickness Al _d Ga _e In _1-de 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-de 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-de N barrier layer (semiconductor light emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 8nm

Table 4 summarizes examples of growth conditions used for the semiconductor light-emitting structure or active region 42 according to the present disclosure.

growth temperature Furtherance thickness Al _d Ga _e In _1-de N barrier layer (semiconductor light emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 4nm Al _f Ga _1-f N first 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 second layer (2) 770℃ Al/(Al+Ga) = 0.85 2nm Al _d Ga _e In _1-de N barrier layer (semiconductor light emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 4nm Al _f Ga _1-f N first 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 second layer (2) 770℃ Al/(Al+Ga) = 0.85 2nm Al _d Ga _e In _1-de N barrier layer (semiconductor light emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 8nm

Table 5 summarizes examples of growth conditions used for the semiconductor light emitting structure or active region 42 according to FIG. 5.

growth temperature Furtherance thickness Al _d Ga _e In _1-de N barrier layer (semiconductor light emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 4nm Al _f Ga _1-f N first 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 second layer (2) 770℃ Al/(Al+Ga) = 0.85 2nm Al _d Ga _e In _1-de N barrier layer (semiconductor light emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 4nm Al _f Ga _1-f N first 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 second 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-de N barrier layer (semiconductor light emitting structure (42 770℃ d = 0, e = 1 (GaN) 4nm

Figure 7 is a diagram showing another example of an experiment result according to the present disclosure, showing the change in emission wavelength according to the composition of Al. On the left is light emission (yellow) when the ratio of Al/(Al+Ga) is 0.25, in the middle is light emission (red) when the ratio of Al/(Al+Ga) is 0.75, and on the right is light emission (red) when the ratio of Al/(Al+Ga) is 0.75. Luminescence (blue) was observed when the ratio was 0.95. Based on the semiconductor light emitting 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 the wavelength shortened again at a certain value of 90% or more Al.

FIG. 8 is a diagram showing another example of an experiment result according to the present disclosure, showing a change in light quantity according to a change in the thickness of the first layer 1 and the second layer 2. When using the structure shown in FIG. 6, it can be seen that the maximum is observed around 2nm and the value drops sharply when it reaches 5nm, and a value of 0.5-4nm can be used.

FIG. 9 is a diagram illustrating another example of an experiment result according to the present disclosure, with the result values when using the semiconductor light-emitting structure shown in FIG. 4(a) on the left, and the semiconductor light-emitting structure shown in FIG. 4(b) on the right. The results when used are shown. You can see that the example on the right is brighter and more reddish.

Figure 10 is a diagram showing another example of an experiment result according to the present disclosure, and the degree of wavelength change according to current was confirmed. Unlike InGaN red LEDs that use existing large amounts of In (the wavelength rapidly shortens as the current amount increases), it can be seen that the wavelength shift is small even when the current amount increases.

FIG. 11 is a diagram illustrating a semiconductor light emitting device related to the present disclosure from the perspective of bandgap energy. (a) shows a conventional semiconductor light emitting device, and (b) shows the semiconductor light emitting device shown in FIG. 2. (c) shows a semiconductor light emitting device in which the barrier layer form of the semiconductor light emitting structure 42 is applied to the superlattice region 31 in the structure shown in (b).

Table 6 summarizes examples of growth conditions used in the semiconductor light emitting device shown in FIG. 11(c).

growth temperature Furtherance thickness Al _g Ga _1-g N third layer (3) 780℃ Al/(Al+Ga) = 0.50 0.8nm In _a Ga _1-a N (superlattice region (31)) 720℃ In/(In+Ga) = 0.55 1.5nm Al _g Ga _1-g N fourth layer (4)) 780℃ Al/(Al+Ga) = 0.50 0.8nm In _b Ga _1-b N (superlattice region (31)) 780℃ b = 0 (GaN) 1.5nm : : : : <<15 cycles>> : : : : Al _g Ga _1-g N third layer (3) 780℃ Al/(Al+Ga) = 0.50 0.8nm In _a Ga _1-a N (superlattice region (31)) 720℃ In/(In+Ga) = 0.55 1.5nm Al _g Ga _1-g N fourth layer (4)) 780℃ Al/(Al+Ga) = 0.50 0.8nm In _b Ga _1-b N (superlattice region (31)) 780℃ b = 0 (GaN) 1.5nm Al _d Ga _e In _1-de N barrier layer (semiconductor light emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 4nm Al _f Ga _1-f N first 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 second layer (2) 770℃ Al/(Al+Ga) = 0.85 2nm Al _d Ga _e In _1-de N barrier layer (semiconductor light emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 4nm Al _f Ga _1-f N first 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 second layer (2) 770℃ Al/(Al+Ga) = 0.85 2nm Al _d Ga _e In _1-de N barrier layer (semiconductor light emitting structure (42)) 770℃ d = 0, e = 1 (GaN) 8nm

12 and 14 are diagrams showing another example of experimental results according to the present disclosure. FIG. 12 is a diagram showing experimental results for the semiconductor light emitting device shown in FIG. 11(c), and FIG. 12 is a diagram showing experimental results for the semiconductor light emitting device shown in FIG. 11(c). This is the result when all growth conditions were kept the same except for the superlattice region 31 in the semiconductor light emitting device, and, like the device shown on the right side of Figure 7, the wavelength shifted again to a shorter wavelength. This means that the superlattice region 31 shown in FIG. 11(c), that is, the third layer 3 and fourth layer 4 structures introduced into the superlattice region 31, are in the well layer of the semiconductor light emitting structure 42. It is believed to play a role in increasing the amount of In injected. Here, 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, and as shown in FIG. 13, red (emission wavelength of 635 nm) It was confirmed that more than twice as much light was emitted compared to the semiconductor light emitting device shown in Figure 11(b). Figure 14 shows the PL measurement results of the superlattice region 31 depending on the presence or absence of the third layer (3) and the fourth layer (4), and the PL measurement results of the superlattice region 31 with the third layer (3) and the fourth layer (4) are shown. It shows that the PL peak shifted significantly from 445 nm to 535 nm on the long wavelength side.

In the semiconductor light emitting device shown in Figure 11(c) in Table 7, the active region 42 of the quantum well structure is changed to the semiconductor light emitting region or active region 42 of the superlattice structure, similar to the superlattice region 31. An example of growth conditions is shown. Figure 15 is a diagram comparing the active area of the quantum well structure and the active area of the superlattice structure. In the active area of the quantum well structure shown on the left, each quantum well produces an isolated band due to a thick barrier layer. However, in the active region of the superlattice structure shown on the right, that is, when the barrier layer is sufficiently thin, each well is not isolated and emits light through electron-hole recombination. It forms a miniband and emits light through a miniband transition. Although the active region of the superlattice structure is a technology that is not generally used in group III nitride-based semiconductor light emitting devices, it was 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 the same as the superlattice region 31, except that 8 cycles were applied, no doping was performed, the growth temperature of the well layer was 700°C, and the growth temperature of the remaining layers was 780°C. ℃, the thickness of the first layer (1) and the second layer (2) was set to 0.8 nm, and the thickness of the Al _d Ga _e In _1-de 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, and the ratio of Al/(Al+Ga) of the first layer (1) and second layer (2) was set to 0.50. , the thickness of the well layer was set to 1.5 nm.

growth temperature Furtherance thickness Al _g Ga _1-g N third layer (3) 780℃ Al/(Al+Ga) = 0.50 0.8nm In _a Ga _1-a N (superlattice region (31)) 720℃ In/(In+Ga) = 0.55 1.5nm Al _g Ga _1-g N fourth layer (4)) 780℃ Al/(Al+Ga) = 0.50 0.8nm In _b Ga _1-b N (superlattice region (31)) 780℃ b = 0 (GaN) 1.5nm : : : : <<15 cycles>> : : : : Al _g Ga _1-g N third layer (3) 780℃ Al/(Al+Ga) = 0.50 0.8nm In _a Ga _1-a N (superlattice region (31)) 720℃ In/(In+Ga) = 0.55 1.5nm Al _g Ga _1-g N fourth layer (4)) 780℃ Al/(Al+Ga) = 0.50 0.8nm In _b Ga _1-b N (superlattice region (31)) 780℃ b = 0 (GaN) 1.5nm Al _d Ga _e In _1-de N barrier layer (semiconductor light emitting structure (42)) 780℃ d = 0, e = 1 (GaN) 4nm Al _f Ga _1-f N first 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 second layer (2) 780℃ Al/(Al+Ga) = 0.50 0.8nm Al _d Ga _e In _1-de N barrier layer (semiconductor light emitting structure (42)) 780℃ d = 0, e = 1 (GaN) 1.5nm : : : : <<8 cycles>> : : : : Al _f Ga _1-f N first 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 second layer (2) 780℃ Al/(Al+Ga) = 0.50 0.8nm Al _d Ga _e In _1-de N barrier layer (semiconductor light emitting structure (42)) 780℃ d = 0, e = 1 (GaN) 8nm

Figure 16 is a diagram showing an example of an experiment result according to the semiconductor light emitting structure shown in Table 7, and it was confirmed that there was a 7-fold increase in output compared to the example shown in Table 6.

FIG. 17 is a diagram illustrating various examples of semiconductor light-emitting structures to which a superlattice structure is applied. In (a), the semiconductor light-emitting devices shown in Table 7 are presented in terms of bandgap energy, and in (b) the superlattice region 31 ) and the layers located on the p side of the semiconductor light emitting structure 42, that is, the second layer 2 and the fourth layer 4, are removed. The semiconductor light emitting device shown in FIG. 17(b) also showed similar experimental results to the semiconductor light emitting device shown in FIG. 17(a). All growth conditions were the same, but the Al/(Al+Ga) ratio of the first layer (1) was changed from 0.50 to 0.65.

Meanwhile, in the semiconductor light emitting device shown in Figure 17(b), the thickness of the Al _d Ga _e In _1-de N barrier layer (d = 0, e = 1 (GaN)) of the semiconductor light emitting structure 42 is 1.5 nm. When changed to 1 nm, the emission wavelength moved to the long wavelength side from 630 nm to 640 nm.

Additionally, in the semiconductor light emitting device shown in FIG. 17(b), when the repetition cycle of the semiconductor light emitting structure 42 was changed from 8 cycles to 16 cycles, the emission wavelength was shortened to 625 nm, and the amount of light was similar.

In addition, in the semiconductor light emitting device shown in Figure 17(b), the thickness of the Al _d Ga _e In _1-de N barrier layer (d = 0, e = 1 (GaN)) of the semiconductor light emitting structure 42 is 1.5 nm. When changed to 0.75nm, the thickness of the first layer (1) was changed from 0.8nm to 0.4nm, and the thickness of the well layer was reduced from 1.5nm to 0.75nm, the wavelength decreased from 630nm to 600nm, and the light quantity decreased to 50nm. decreased by more than %.

In addition, in the semiconductor light emitting device shown in Figure 17(b), the thickness of the Al _d Ga _e In _1-de N barrier layer (d = 0, e = 1 (GaN)) of the semiconductor light emitting structure 42 is 1.5 nm. When changed to 1.0 nm, leaving the thickness of the first layer (1) at 0.8 nm, and increasing the thickness of the well layer from 1.5 nm to 2.0 nm, the wavelength significantly increased from 630 nm to 680 nm, and the light intensity decreased by about 50%. did. Under these conditions, by changing the growth temperature to a higher level, the emission wavelength could be increased to 630 nm, and the amount of light increased by 20% compared to the semiconductor light emitting device shown in Figure 17(b).

Changes such as adding dopants, adding Al, In, or Ga to each layer constituting the superlattice region 31 and the semiconductor light emitting structure 42, or slightly changing the composition and growth conditions during the repetition process. Of course, it can be given.

FIG. 18 is a diagram 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, and 35. In the example, the 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 enhancement layer is provided between the superlattice region 34 and the superlattice region 35. (37) is provided.

The superlattice regions 33, 34, and 35 are sequential repetitive stacks of AlGaN-InGaN-GaN, sequential repetitive stacks of GaN-InGaN-AlGaN, sequential repetitive stacks of GaN-AlGaN-InGaN-AlGaN, or sequential repetitive stacks of AlGaN-InGaN. It is sufficient that the AlGaN-InGaN interface exists in the superlattice regions 33, 34, 35, and AlInGaN is present either by diffusion or intentionally by forming the AlGaN-InGaN interface. Let's do it. In existing group III 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 The regions 33, 34, and 35 are used for this function as well as to allow a lot of In to enter the active region 42. In other words, the difference in lattice constants between GaN and InGaN makes it difficult for In to enter the active region. However, by increasing the In content through the superlattice regions (33, 34, 35), In is more efficient in the active region (42). You can put a lot into it. For reference, by adding In to the superlattice region 33, more In can be added to the superlattice region 34 even if the same growth conditions are used as the superlattice region 33, and the superlattice region 35 ) is also the same.

The superlattice regions 33, 34, and 35 formed in this way do not have a flat surface due to the AlGaN-InGaN interface, but 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 the crystal defects of the device, a lateral growth reinforcement layer 36 is introduced to undergo a planarization process, and the superlattice region 34 is formed again. This facilitates the injection of In into the active region 42, while the lateral growth enhancement layer 37 is again introduced to eliminate crystal defects. There may be one or more superlattice regions 33, 34, and 35, and there is no upper limit. However, as shown in FIG. 21, it is more preferable not to introduce a lateral growth reinforcement layer between the active region 42 and the superlattice region 35 closest thereto. The rough surface S is made of a semi-polar facet. For example, when the growth substrate 10 is a C-plane sapphire substrate, the flat group III nitride semiconductor grown on it is grown along the c-axis. Although it has a polar face, the three-dimensional surface that makes up the rough surface (S) constitutes a semi-polar face. In the case of a polar plane, injection of In is easy, but it has the disadvantage of having a large piezo constant (if the piezo constant is large, the wavelength may shift significantly toward a short wavelength as the current density increases), and in the case of a non-polar plane, the piezo constant is large. Although the constant is 0, it has the disadvantage of making In injection difficult. In the present disclosure, the active region 42 is grown on a rough surface (S), that is, a semipolar surface, thereby facilitating the injection of In and having an appropriate piezoelectric constant. As shown in FIG. 21, the last barrier layer of the active region 42, that is, the last barrier 44, may be grown flatly by adjusting the growth conditions, or may be grown to have a shape following the rough surface S. possible.

Table 8 shows an example of growth conditions for the semiconductor light emitting structure shown in FIG. 18.

Growth temperature (℃) Furtherance Thickness (nm) GaN (superlattice 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 : : : : <<10 cycles>> : : : : GaN (lateral growth enhancement layer (36)) 830 100 GaN (superlattice 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 : : : : <<10 cycles>> : : : : GaN (lateral growth enhancement 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 (superlattice region (35)) 830 1.5 : : : : <<10 cycles>> : : : : In _x Ga _1-x N (active region (42)) 710 x=0.35 2.2 In _x Ga _1-x N (active region (42)) 760 x=0.05 0.4 Al _y Ga _1-y N (active region (42)) 760 y=0.1 0.8 In _x Ga _1-x N (active region (42)) 760 x=0.05 0.4 : <<Cycle 3>> : Al _y Ga _1-y N (Last Barrier (44))
GaN (Last Barrier (44))
In _x Ga _1-x N (Last Barrier (44)) 760
760
760 y=0.05

x=0.05 6
6
6 Al _y Ga _1-xy In _x N (electron blocking layer (51)) 820 x=.0.1,y=0.2 20 p-GaN (p-side contact area 52) 900 200

The thickness of the lateral growth reinforcement layer (36,37) is sufficient to cover the rough surface (S), and there is no upper limit, but if it becomes too thick (e.g., 500 nm), the thick GaN layer will be in the active area ( 42) There is concern that the function of the superlattice regions 33 and 34 will be greatly reduced due to their previous location.

Here, unlike the previous examples, the compositions of In, Al, and Ga used were predicted values in the solid state after growth was completed. For reference, even if _it is the same _In do.

The last barrier (44) was Al _y Ga _1-y N (44; y=0.05), GaN (44), and In _x Ga ₁ -x N (44; x=0.05), respectively, and Al _y Ga _1- The best light output was shown when _y N (44; y=0.05). Additionally, in a typical LED device, when Al is added to the last barrier 44, a short-wavelength transition is shown, and when In is added, a long-wavelength transition is shown. However, in the device presented in this example, when Al is added, a long-wavelength transition is shown, and when In is added, a short-wavelength transition is shown. showed. It can be seen that the desired red light wavelength can be obtained by controlling the Al content and In content, and a behavior opposite to the existing understanding was used, which is presumed to be a strain effect. Omitting the last In _0.05 Ga _0.95 N (0.4 nm)-Al _0.1 Ga _0.9 N (0.8 nm)-In _0.05 Ga _0.95 N (0.4 nm) of the 3rd cycle in the active region 42 shown in Table 8, Al _0.05 Ga _0.95 N (last barrier (44)); 6 nm) _, GaN (last barrier ₄₄ ; ₆ nm) or _In nm)-Al _0.1 Ga _0.9 N (0.8 nm)-In _0.05 Ga _0.95 N (0.4 nm)-Al _0.05 Ga _0.95 N (6 nm), more effective when composed only of Al _0.05 Ga _0.95 N (6 nm) was good, and when composed of In _0.05 Ga _0.95 N (0.4 nm)-Al _0.1 Ga _0.9 N (0.8 nm)-In _0.05 Ga _0.95 N (0.4 nm)-In _0.05 Ga _0.95 N (6 nm), In _0.05 Ga _0.95 N The effect was better than when composed of only (6 nm), and the effect of using Al _0.05 Ga _0.95 N (6 nm) was better than that of In _0.05 Ga _0.95 N (6 nm) and GaN (6 nm) (see Figure 23) .

The region corresponding to the well layer within the active region 42 (the example presented is a form in which the active region 42 has a superlattice structure to form a mini band, but for convenience, it is a well layer used in the quantum well structure, The expression “barrier layer” is used as is.) In _x Ga _1-x N ₍ active region 42 _{; -x} N (active area 42; x=0.05)-Al _y Ga _1-y N(active area 42; y=0.1)-In _x Ga _1-x N(active area 42; x= It has the characteristic of being thicker than the thickness of 0.05 (1.6nm=0.4nm+0.8nm+0.4nm). It was also confirmed that the thinner the barrier layer and the thicker the well layer in the active region 42, the longer the wavelength (see FIG. 24).

In addition, as shown, efficiency was increased by using a barrier layer in the form of InGaN-AlGaN-InGaN instead of using a single GaN barrier (see FIG. 25).

In addition, after the growth of the last barrier 44, the electron blocking layer 51 was grown with AlInGaN instead of AlGaN, and the efficiency increased by 10% by moving to a longer wavelength (see Figure 26).

FIG. 22 is a diagram showing another example of a semiconductor light emitting structure according to the present disclosure. Unlike the semiconductor light emitting device shown in FIG. 18, the superlattice regions 33 and 34 are transformed into strain control regions 38 and 39. It has been replaced. In general, a superlattice structure refers to a structure in which two or more layers with different band gaps are grown alternately, each having a thickness of several nm, and tunneling occurs to form a miniband.

Table 9 shows an example of growth conditions for the semiconductor light emitting structure shown in FIG. 18.

Growth temperature (℃) Furtherance Thickness (nm) GaN (area (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 : : : : <<10 cycles>> : : : : GaN (lateral growth enhancement layer (36)) 1000 45 GaN (superlattice 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 : : : : <<10 cycles>> : : : : GaN (lateral growth enhancement 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 (superlattice region (35)) 830 1.5 : : : : <<10 cycles>> : : : : In _x Ga _1-x N (active region (42)) 710 x=0.35 2.2 In _x Ga _1-x N (active region (42)) 760 x=0.05 0.4 Al _y Ga _1-y N (active region (42)) 760 y=0.1 0.8 In _x Ga _1-x N (active region (42)) 760 x=0.05 0.4 : <<Cycle 3>> : Al _y Ga _1-y N (Last Barrier (44))
GaN (Last Barrier (44))
In _x Ga _1-x N (Last Barrier (44)) 760
760
760 y=0.05

x=0.05 6
6
6 Al _y Ga _1-xy In _x N (electron blocking layer (51)) 820 x=.0.1,y=0.2 20 p-GaN (p-side contact area 52) 900 200

In order to emit red light, a relatively high In content is required in the active region 42, and the superlattice region alone is sufficient to overcome crystal defects caused by a sharp difference in lattice constants between the n-side semiconductor region 30 and the active region 42. In cases where this is not easy, this problem can be solved by introducing one or more strain control regions 38 and 39.

The strain control regions 38 and 39 were 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 regions 38 and 39 can be improved.

In the strain control region (38,39), the thickness of In _x Ga _1-x N is set to be several tens of nm (e.g. 30 nm), the composition It can be set at 10nm~200nm, and for the Al _y Ga _1-y N layer, y can be set at 0.01<y<0.9, and the thickness can be set at 1~20nm. It is desirable that the growth temperature difference (delta T) between In _x Ga _1-x N and GaN differs by at least 20 degrees. The growth temperature of GaN was higher than that of In _x Ga _1-x N.

Compared to the example shown in Table 8, the thickness of the side growth reinforcement layer 36 was reduced from 100 nm to 45 nm, and when the degree of rough surface (S) is less than that shown in Table 8, the side growth layer 36 is reduced to a thickness of 50 nm or less. A growth reinforcement layer 36 can be formed.

FIG. 27 is a diagram illustrating another example of a semiconductor light emitting device according to the present disclosure. Unlike the examples shown in FIGS. 1, 2, 18, and 22, a growth prevention film 21 (e.g., SiO) is formed on the growth substrate 10. ₂ ) is provided, and the semiconductor light emitting portions (A; 20, 30, 42, 50) are grown from the growth substrate 10 exposed through the opening 21 formed in the growth prevention film 21. In this selective growth (Selective Expitaxy), the growth rate of the semiconductor light emitting portion (A) can be controlled by adjusting the size of the opening 22, that is, the size of the pattern. If the size of the opening 22 is reduced, the growth speed becomes faster, and the thickness of the grown semiconductor light emitting portion A becomes thicker. Accordingly, the thickness of the active region 42 becomes thicker to have a Quantum Confinement Effect, and the amount of In injected also increases to emit longer wavelength light. Of course, when an InGaN layer is provided under the active region 42, the In content of this layer can be increased. Although the buffer region 20, n-side contact region 30, active region 42, and p-side region 50 are presented as examples of the semiconductor light emitting unit (A), not only can the various structures described above be applied, It can also be applied to conventionally presented semiconductor light emitting unit structures.

FIG. 28 is a diagram illustrating another example of a semiconductor light emitting device according to the present disclosure. Unlike the example shown in FIG. 27, the buffer area 20 is provided below the growth prevention film 21. Various examples of such structures are presented in the applicant's International Publication No. WO/2019/199144.

FIG. 29 is a diagram showing another example of a semiconductor light emitting device according to the present disclosure. Unlike the example shown in FIG. 28, the growth prevention film 21 is omitted, and a portion of the buffer region 20 is etched to show an etched region ( In E), an example is presented in which growth is prevented from occurring so that the etched area E replaces the growth prevention film 21 and the semiconductor light emitting portion A is selectively grown. At this time, it is possible to adjust the emission wavelength of the active region 42 by adjusting the size of the upper surface of the etched remaining buffer region 20 or the size of the etched region E. The growth prevention film 21 and the etched area (E) shown in FIG. 28 are collectively referred to as the growth prevention region (21,E), and if the growth prevention film 21 can be applied in the present disclosure, it is referred to as the etched area (E). can be replaced Of course, the n-side contact area 30 can be grown on the buffer area 20 and the etched area E can be created by etching them.

FIG. 30 is a diagram showing another example of a semiconductor light emitting device according to the present disclosure. Unlike the example shown in FIG. 28, the buffer region 20 and the n-side contact region 30 are provided below the growth prevention film 21. there is.

FIG. 31 is a diagram showing another example of a semiconductor light emitting device according to the present disclosure. Unlike the example shown in FIG. 28, the growth prevention film 21 is provided with openings 22, 23, and 24 of different sizes. The semiconductor light emitting portions (A, B, and C) grown in each opening (22, 23, and 24) are grown under one growth condition, but their thickness and In content in the active region 42 are different, and thus the semiconductor light emitting portions (A, B, and C) are grown under one growth condition. It emits light. For example, the semiconductor light emitting part (A) grown in the smallest opening 22 emits the longest wavelength light (e.g. red), and the semiconductor light emitting part (A) grown in the largest opening 24 ( C) emits light of the shortest wavelength (e.g. blue), and the semiconductor light emitting part (B) grown in the medium-sized opening 23 can be designed to emit light of medium wavelength (e.g. green). . Of course, the form shown in Figure 28 can be used.

FIG. 32 is a diagram showing an example of the opening pattern shown in FIG. 31, in which many openings 22 of the smallest size are arranged in the same area (e.g., 6), and the openings 24 of the largest size are arranged in the same area. By arranging the fewest number of openings 23 (e.g., 1) and the average number of openings 23 (e.g., 4) in the same area, the semiconductor light emitting units (A, B, C) formed thereon are disposed. The amount of light can be adjusted.

Figure 33 is a diagram showing another example of the arrangement of the openings of the growth prevention film 21 according to the present disclosure, in which the openings 22 of the growth prevention film 21 are arranged at narrow intervals on the left, and the openings of the growth prevention film 21 are on the right. (22) are placed at wide intervals. The size of the opening 22 is the same. Under given growth conditions, if the spacing between the openings 22 is widened, the source supply to each opening 22 becomes more sufficient, allowing the openings 22 to be thick and have sufficient In content. Of course, the effect described in FIG. 31 can be achieved by varying the spacing between the openings 22 in one growth prevention film 21. If the opening 22 is replaced by the etched remaining area (see Figure 28), the same principle applies. In the present disclosure, adjusting the size and spacing of the growth prevention area (22,E) is collectively referred to as pattern control of the growth prevention area (22,E).

FIGS. 34 to 36 are diagrams showing an example of a method for manufacturing a semiconductor light emitting device according to the present disclosure. As shown in FIG. 34, a semiconductor film is fabricated without forming a growth prevention film 21 on the n-side contact region 30. The active region 42 and p-side region 50 of the light emitting portion C are grown. Next, as shown in FIG. 35, part of the active region 42 and the p-side region 50 of the semiconductor light emitting unit C is removed through etching and the n-side contact region 30 is exposed. Finally, as shown in FIG. 36, the growth prevention film 21 is formed, and then the openings 22 and 23 are formed, and then the semiconductor light emitting unit (A) 42,50 is formed through one growth process. ) and a semiconductor light emitting part (B; 42,50). These growth conditions are adjusted so that the active region 42 of the semiconductor light emitting portion (A) grown in the opening 22 emits red color, and the size of the opening 23 is adjusted so that the semiconductor light emitting portion (B) emits green color. It can be adjusted. Since there is a large difference in wavelength between red and blue, the semiconductor light emitting part C that emits blue light can be formed through pre-growth and then etching, rather than using selective growth. It also has the advantage of being able to adjust the size of the semiconductor light emitting unit (C) regardless of the color of the light. Of course, the active region 42 and the p-side region 50 of the semiconductor light emitting portion (A) can be grown first, or the active region 42 and the p-side region 50 of the semiconductor light emitting portion (B) can be grown first. am.

FIGS. 37 to 40 are diagrams showing another example of a method for manufacturing a semiconductor light emitting device according to the present disclosure. As shown in FIG. 37, a growth prevention film 21 is formed in the state shown in FIG. 35, Semiconductor light emitting portions (A; 42 and 50) are grown in the n-side contact region (30). Next, as shown in FIG. 38, an etch mask 25 is formed, and as shown in FIG. 39, the semiconductor light emitting portions (A) 42 and 50 are left with a predetermined size, while some are formed with nanowires. Leave it as Structure (N). Finally, as shown in FIG. 40, a cladding region (26; e.g., SiO ₂ ) is formed on the nanowire structure (N) to form semiconductor light emitting units (B) 42 and 50 made of nanowires. For example, the semiconductor light emitting part (C) is designed to emit blue color, the semiconductor light emitting part (A) is designed to emit red light, and then the semiconductor light emitting part (B) is formed into a nanowire structure so that they do not interfere with each other. It is possible to implement a three-color light-emitting monolithic LED through two independent growth conditions. Of course, the size of the semiconductor light emitting parts (A, B, C) can be adjusted as desired. Although the semiconductor light emitting units (A, B, C) can be implemented in the form shown in FIG. 27 and in the form shown in FIG. 28, the presented example has the advantage of using the n-side contact area 30 as a common electrode (Size-Dependent Strain Relaxation and Optical Characteristics of InGaN/GaN Nanorod LEDs; IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS, VOL. 15, NO. 4, JULY/AUGUST 2009) .

FIG. 41 is a diagram showing an example of an experiment result according to the method shown in FIGS. 27 to 33. The semiconductor light emitting part (A) shown on the left emits red (e.g., 610 nm), and the semiconductor light emitting part (A) shown on the right emits red (e.g., 610 nm). B) emits green (e.g., 550 nm), and the semiconductor light emitting part (D) shown in the middle emits orange to yellow (e.g., 580 nm). In the experiment, regular hexagonal openings with side lengths of 14㎛, 23㎛, and 40㎛ were used (see Figure 32), and the spacing between openings was 10㎛. It can be seen that as the size of the aperture decreases, the emission peak wavelength becomes longer. As described above, the smaller the opening, the faster the growth rate, which increases the thickness of the superlattice region (SL) and the active region 42, and also increases the amount of In injection, which is believed to emit light with a relatively longer wavelength. . Compared to the growth conditions of the active region 42 shown in Table 9, in the case of selective growth using openings with a size of 14㎛ and a spacing of 10㎛, the supply amount of In/(In+GaN) is set to 60%, and the well It is possible to create a red light-emitting group III nitride semiconductor light-emitting device shown in FIG. 41 by using conditions that allow the thickness of the layer and barrier layer to grow by about 50%, and the present disclosure is implemented through selective growth of various colors on a single wafer. In addition, by using selective growth, it can be expanded to implement a red light-emitting group III nitride semiconductor light-emitting device by supplying a smaller amount of In than when selective growth is not used.

Figure 42 is a diagram showing another example of experimental results according to the method shown in Figures 27 to 33, where the semiconductor light emitting part (A) shown on the left emits red (e.g. 610 nm), and the semiconductor light emitting part shown in the middle emits red (eg, 610 nm). (E) has a width (e.g., 6 μm) smaller than the width of the semiconductor light emitting portion (A) (i.e., size of the opening; 14 μm), but emits blue light (e.g., 450 nm), and is shown on the right. (F) has the same width (23 μm) as the semiconductor light emitting portion (D) of Figure 41, but emits white light instead of orange or yellow. The fact that the semiconductor light emitting part (E) emits light of a shorter wavelength rather than a longer wavelength is inconsistent with the interpretation of the results of the previous experiment, which is consistent with the C-plane sapphire growth substrate (10; see FIGS. 27 to 31). ), while the active region 42 in each of the semiconductor light-emitting portions (A), semiconductor light-emitting portions (B), and semiconductor light-emitting portions (D) is grown on the top surface (T), that is, the (0001) plane, This is believed to be because the light emitting unit (E) has a small opening, so the active area (42L) is formed not on the top surface (T) but on the side (L), that is, the (11-22) plane. In the case of the (11-22) plane, the growth rate is about 1/2 to 1/7 slower than that of the (0001) plane, and In injection is relatively difficult, so it is presumed to emit blue light. In the case of the semiconductor light emitting part (F), the width (e.g., 23㎛) was the same as that of the semiconductor light emitting part (D), but the gap between openings (see Figure 33) was set at 30㎛ instead of 10㎛, and the gap As this increases, assuming that the growth gas is uniformly supplied within the MOCVD equipment, there is a lot of growth gas around the semiconductor light emitting part (F) with a wide gap, so the growth rate becomes faster, and therefore, compared to the semiconductor light emitting part (D). As it grows into a tall shape, an active area 42T and an active area 42L are formed on the top surface (T) and the side surface (L), and the active area 42T on the top surface (T) emits orange to yellow light. , The active area 42L on the side (L) emits blue light, and since orange to yellow and blue are complementary colors, it appears white.

Figure 43 is a graph summarizing the experimental results presented in Figures 41 and 42. Overall, as the size of the openings (22, 23, 24; see Figure 32) decreases, the peak emission wavelength shifts to a longer wavelength, but under given growth conditions, If the opening is smaller than the size at which the active region 42L is formed on the side surface (L; e.g., (11-22) plane) of the semiconductor light emitting portion (A, E, F; see Figure 42), the active region 42L is formed on the side surface (L). A region 42L is formed, and the active region 42L emits light with a relatively shorter wavelength than the light emitted from the active region 42T formed on the upper surface T. In addition, an active region 42T and an active region 42L are grown on each of the top surface (T) and the side surface (L), and growth conditions and growth prevention regions 22 and E are set so that each of them emits light in a complementary color relationship. It shows that one semiconductor light emitting part (F) can emit white light by adjusting the pattern of .

Figure 44 is a diagram showing an example of the results of a light excitation (PL) experiment according to the present disclosure, from the left: u-GaN absorption result with excitation light of 325 nm wavelength, p-GaN absorption result with excitation light of 325 nm wavelength, and 405 nm wavelength. The active layer absorption results are shown with excitation light. In all cases, only very weak and identical deep level emission was measured, and even when light was selectively absorbed by u-GaN, p-GaN, and the active layer, the same, very weak emission spectrum was observed. There was no peak shift at all due to the application of bias (since the bias is applied only to the active layer, meaning that it is not active emission), and in the case of 405 nm excitation, only a slight decrease in intensity was seen due to the application of reverse bias (same deep level throughout the sample, including the active layer). exists).

Figure 45 is a diagram showing an example of the results of an electroluminescence (EL) experiment according to the present disclosure. EL according to current injection starts at a longer wavelength that is completely different from PL, and in EL, the intensity is dozens of times greater than the PL intensity. Light emission was observed at longer wavelengths, and photoluminescence corresponding to EL was not observed even in low-temperature PL and high excitation PL. The operating voltage of EL is smaller than the minimum operating voltage (hv/e) obtained by the emission wavelength. The above results indicate that PL emission and EL emission occur in spatially different and separate regions.

Figure 46 is a diagram showing an example of the results of an electroluminescence (EL) experiment with a laser added according to the present disclosure. When the laser is additionally irradiated with the EL turned on, the intensity of the EL increases dramatically (more than 3 times). In the case of only laser irradiation, a very weak other PL was observed as described above, and when excitation light was added when observing EL by applying a forward voltage, the EL intensity increased nonlinearly, and the degree depended on the wavelength of the excitation light. The laser irradiated at this time is a laser with a wavelength of 405 nm, and the energy of the laser is greater than the energy of the well layer and less than the energy of the barrier layer or p-GaN or n-GaN layer. That is, the laser is selectively absorbed only in the well layer.

To summarize the experimental results of Figures 44 to 46, ① EL is observed, but PL is not observed. ② During PL, absorption by the excitation laser occurs in the quantum well layer. Photocurrent measurement results experimentally confirm this. ③ In PL, laser absorption occurs in the quantum well layer, but emission from the quantum well layer is not observed. ④ In the quantum well layer, the density of non-radiative recombination centers is large, so the photoluminescence efficiency is very low. ⑤ EL occurs in another area spatially separated from PL.

Figure 47 schematically shows the light emission mechanism that conforms to this theorem, that is, light emission through Tunneling Injection (Paper: Tunnel Injection and Power Efficiency of InGaN/GaN Light-Emitting Diodes; ISSN 1063-7826, Semiconductors, 2013, Vol. 47, No. 1, pp. 127-134. Electrons are injected by tunneling into a low energy state in the AlGaN barrier layer. In EL, electron-hole recombination occurs by avoiding the quantum well layer, which has a high non-radiative recombination center density, and the barrier layer has a low non-radiative recombination center density, enabling high efficiency low energy (long wavelength) light emission and low operating voltage. It is judged that observation of EL has become possible (see Figure 48).

Unlike existing GaN-based LEDs, it is necessary to examine what enables light emission through Tunneling Injection in the semiconductor light emitting device according to the present disclosure. As shown in FIG. 21, the active region 42 and the superlattice region closest thereto This light emission occurred when the laterally grown reinforcement layer (36 or 37) was not introduced between (35), but this was not the case when the laterally grown reinforcement layer (36 or 37) was introduced. Therefore, apart from the interpretation that in the case where the lateral growth reinforcement layer (36 or 37) is not provided, the active region (42) is grown on a semi-pole surface, injection of In can be increased, and the rough surface (S) created It can be interpreted that tunneling injection is possible by growing the active area (42) without recovering defects through the side growth reinforcement layer (36 or 37).

As shown in Figure 49, as the barrier thickness becomes thinner, coupling between the last QW and the second QW occurs, the energy state of the QW is split into two, and the energy of the ground state becomes lower (wavelength becomes longer). ) (Paper: Effect of electric fields on excitons in a coupled double-quantum-well structure; PHYSICAL REVIEW B VOLUME 36, NUMBER 8 15 SEPTEMBER 1987-I), and this interpretation is based on the experimental results presented in FIG. It is also consistent with the result that 'It was confirmed that the thinner the barrier layer and the thicker the well layer in the active region 42, the longer the wavelength.' Therefore, according to the experimental results and analysis according to the present disclosure, the emission wavelength can be controlled to a long wavelength by thinning the thickness of the last barrier and increasing the thickness of the last well layer.

Below, various embodiments of the present disclosure are described.

(1) A method of manufacturing a group III nitride semiconductor light-emitting structure that emits red light with an emission peak wavelength of 600 nm or more, the step of growing a first superlattice region made of repeated stacking of a first sub-layer and a second sub-layer. ; And, on the first superlattice region, a third sublayer is made of a group III nitride semiconductor containing Al and has a first band gap energy, and a third sublayer is made of a group III nitride semiconductor containing In and has a first band gap energy smaller than the first band gap energy. Growing an active region including a fourth sub-layer having a second band gap energy and a fifth sub-layer made of a group III nitride semiconductor containing Al and having a third band gap energy greater than the second band gap energy. In the step of growing the active region, when the In content of the fourth sub-layer is changed to GaN, the fourth sub-layer emits light with a peak emission wavelength of 600 nm or less. A method of manufacturing a group III nitride semiconductor light-emitting structure, wherein the Al content of the third sub-layer and the Al content of the fifth sub-layer are set to emit red light having an emission peak wavelength of 600 nm or more in the fourth sub-layer.

(2) A method of manufacturing a group III nitride semiconductor light-emitting structure, wherein the active region includes a quantum well structure, the fourth sub-layer is a quantum well layer, and the third and fifth sub-layers are quantum barrier layers. (see Figure 3)

(3) A method of manufacturing a group III nitride semiconductor light-emitting structure in which the supply of In is decreased and then increased during the process of growing the fourth sub-layer. (see Figure 4)

(4) In the step of forming the active region, the third sub-layer, fourth sub-layer, and fifth sub-layer are sequentially grown multiple times, and the fifth sub-layer provided on the uppermost side has the peak emission wavelength of the entire active region. A method of manufacturing a Group III nitride semiconductor light-emitting structure containing InGaN to move to a long wavelength. (see Figure 5)

(5) A method of manufacturing a group III nitride semiconductor light-emitting structure in which the fifth sub-layer provided on the uppermost side is made of InGaN-GaN.

(6) A method of manufacturing a group III nitride semiconductor light-emitting structure in which the third sub-layer and the fifth sub-layer are each made of AlGaN-GaN-AlGaN.

(7) The first sub-layer has a fourth band gap energy, the second sub-layer has a fifth band gap energy greater than the fourth band gap energy, and the second sub-layer has AlGaN-(In)GaN, AlGaN- A method of manufacturing a group III nitride semiconductor light-emitting structure made of (In)GaN-AlGaN or (In)GaN-AlGaN. (See Figure 11(c))

(8) A method of manufacturing a group III nitride semiconductor light-emitting structure, wherein the Al content of AlGaN in the second sub-layer is greater than the Al content in the third sub-layer and the Al content in the fifth sub-layer.

(9) A method of manufacturing a group III nitride semiconductor light-emitting structure in which the active region includes a superlattice structure. (See Table 7)

(10) A method of manufacturing a group III nitride semiconductor light-emitting structure in which the third sub-layer and the fifth sub-layer are made of GaN-AlGaN. (See Figure 17(b))

Growth substrate 10, buffer region 20, n-side contact region 30, superlattice region 31, active region 42, electron blocking layer 51, p-side contact region 52, current diffusion Electrode 60, first electrode 70, second electrode 80

Claims (1)

Method for manufacturing a group III nitride semiconductor light-emitting structure.