A color-controllable monolithic LED, its preparation method and application

Abstract

The present invention discloses a color-controllable monolithic LED and its preparation method and application. The color-controllable monolithic LED of the present invention comprises a substrate, a metal bonding layer, a first insulating layer, a mirror metal layer, a first p-type GaN layer, a first AlGaN electron blocking layer, a first InGaN / GaN multi-quantum well layer, an n-type GaN layer, a second InGaN / GaN multi-quantum well layer, a second AlGaN electron blocking layer, a second p-type GaN layer, a transparent current diffusion layer, a second insulating layer, a first p electrode, an n electrode and a second p electrode. The first and second InGaN / GaN multi-quantum well layers are each independently one of a red light quantum well layer, a green light quantum well layer, a blue light quantum well layer, and a yellow light quantum well layer. The monolithic LED of the present invention can achieve multi-color controllable light emission, has good color uniformity, and high device quality.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and particularly relates to a color-controllable monolithic LED and its preparation method and application. Background Technique

[0002] Light-emitting diodes (LEDs) are typical monochromatic light sources. Ideal additive mixing in the visible spectrum makes them very suitable for color-tunable light sources in mood lighting, panel displays, and visible light communication. Currently, in the process of achieving multi-color regulation and white light, LED chips of red-green-blue (RGB) light are mostly connected in parallel. However, since the emission cones of the parallel devices do not completely overlap with each other, color changes in space will result in non-ideal color mixing. Optical mixing methods (such as inserting additional diffusers) can promote the overlap of radiation patterns from discrete emitters, but inevitably introduce optical losses and losses in color sharpness and richness. In summary, the existing LEDs cannot fully meet the requirements of practical applications.

[0003] Therefore, it is of great significance to develop a monolithic LED that meets the requirements of high uniformity. Summary of the Invention

[0004] The purpose of the present invention is to provide a color-controllable monolithic LED and its preparation method and application.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A color-controllable monolithic LED, which comprises a substrate, a metal bonding layer, a first insulating layer, a mirror metal layer, a first p-type GaN layer, a first AlGaN electron blocking layer, a first InGaN / GaN multiple quantum well layer, an n-type GaN layer, a second InGaN / GaN multiple quantum well layer, a second AlGaN electron blocking layer, a second p-type GaN layer, a transparent current diffusion layer, and a second insulating layer, which are sequentially stacked; and further comprises a first p electrode, an n electrode, and a second p electrode; the first p electrode forms an ohmic contact with the first p-type GaN layer; the n electrode forms an ohmic contact with the n-type GaN layer; the second p electrode forms an ohmic contact with the second p-type GaN layer; the first InGaN / GaN multiple quantum well layer and the second InGaN / GaN multiple quantum well layer are each independently one of a red light quantum well layer, a green light quantum well layer, a blue light quantum well layer, and a yellow light quantum well layer.

[0007] Preferably, the substrate is a Si substrate with a thickness of 50 μm to 500 μm.

[0008] Preferably, the composition of the metal bonding layer is at least one of Ni, Au, Sn, and Ti, and the thickness is 0.5 μm to 5 μm.

[0009] Preferably, the first insulating layer is a SiO2 layer with a thickness of 100 nm to 2000 nm.

[0010] Preferably, the mirror metal layer is composed of multiple SiO2 layers and multiple TiO2 layers arranged alternately, with a thickness of 0.5 μm to 4 μm.

[0011] Preferably, the thickness of the first p-type GaN layer is 10 nm to 300 nm.

[0012] Preferably, the thickness of the first AlGaN electron blocking layer is 20 nm to 40 nm.

[0013] Preferably, the thickness of the first InGaN / GaN multiple quantum well layer is 20 nm to 100 nm.

[0014] Preferably, the thickness of the n-type GaN layer is 0.5 μm to 5 μm.

[0015] Preferably, the thickness of the second InGaN / GaN multiple quantum well layer is 20 nm to 100 nm.

[0016] Preferably, the thickness of the second AlGaN electron blocking layer is 20 nm to 40 nm.

[0017] Preferably, the thickness of the second p-type GaN layer is 10 nm to 300 nm.

[0018] Preferably, the transparent current spreading layer is one of a transparent In oxide conductive film, a transparent Sb oxide conductive film, a transparent Zn oxide conductive film, and a transparent Sn oxide conductive film, with a thickness of 10 nm to 800 nm.

[0019] Preferably, the second insulating layer is a SiO2 layer with a thickness of 100 nm to 2000 nm.

[0020] Preferably, the composition of the first p-electrode includes at least one of Cr, Pt, and Au.

[0021] Preferably, the composition of the n-electrode includes at least one of Cr, Pt, and Au.

[0022] Preferably, the composition of the second p-electrode includes at least one of Cr, Pt, and Au.

[0023] The preparation method of the above color-controllable monolithic LED includes the following steps:

[0024] 1) Growing a buffer layer, an n-type GaN layer, a first InGaN / GaN multiple quantum well layer, a first AlGaN electron blocking layer, and a first p-type GaN layer on an epitaxial substrate in sequence;

[0025] 2) Strip the epitaxial substrate and the buffer layer to expose the n-type GaN layer;

[0026] 3) Grow a second InGaN / GaN multi-quantum well layer, a second AlGaN electron blocking layer, and a second p-type GaN layer on the n-type GaN layer, and then fabricate a transparent current spreading layer on the second p-type GaN layer;

[0027] 4) Fabricate vias that radially penetrate to the first p-type GaN layer and vias that radially penetrate to the n-type GaN layer;

[0028] 5) Grow a second insulating layer on the upper surface of the transparent current spreading layer and on the inner walls of the via structure, where the inner walls do not include the bottom surface of the vias;

[0029] 6) Provide a grooved structure on the second insulating layer that penetrates to the second p-type GaN layer, and then deposit a first p-electrode, an n-electrode, and a second p-electrode in the via structure and the grooved structure;

[0030] 7) Deposit a mirror metal layer, a first insulating layer, and a metal bonding layer on the first p-type GaN layer, and then bond the metal bonding layer to the substrate to obtain a color-controllable monolithic LED.

[0031] Preferably, the method for stripping the epitaxial substrate in step 2) is one of mechanical thinning, chemical polishing, and laser lift-off.

[0032] Preferably, the method for stripping the buffer layer in step 2) is ICP dry etching.

[0033] Preferably, the method for fabricating the transparent current spreading layer in step 3) is pulsed laser deposition process.

[0034] Preferably, the method for fabricating the vias in step 4) is photolithographic lift-off or ICP dry etching.

[0035] A light source, the composition of which includes the above-mentioned color-controllable monolithic LED.

[0036] The beneficial effects of the present invention are as follows: The monolithic LED of the present invention can achieve multi-color controllable light emission, has good color uniformity, and high device quality.

[0037] Specifically:

[0038] 1) The monolithic LED of the present invention uses a vertical structure to replace the parallel structure, which can solve the problem that the emission cones in parallel devices do not completely overlap with each other, ensuring color uniformity;

[0039] 2) The monolithic LED of the present invention can achieve multi-color controllable light emission, and by providing an isolation layer, the stress between multiple light-emitting units is reduced, improving the device quality. Description of the Drawings

[0040] Figure 1 It is a schematic structural view of the cross-section of the color-controllable monolithic LED of Embodiment 1.

[0041] Figure 2 It is a top view of the color-controllable monolithic LED of Embodiment 1.

[0042] Description of the drawing reference numerals: 10, Si substrate; 20, metal bonding layer; 30, first insulating layer; 40, mirror metal layer; 50, first p-type GaN layer; 60, first AlGaN electron blocking layer; 70, first InGaN / GaN multi-quantum well layer; 80, n-type GaN layer; 90, second InGaN / GaN multi-quantum well layer; 100, second AlGaN electron blocking layer; 110, second p-type GaN layer; 120, transparent current diffusion layer; 130, second insulating layer; 140, first p electrode; 150, n electrode; 160, second p electrode. Detailed Embodiments

[0043] The present invention will be further explained and illustrated below with reference to specific embodiments.

[0044] Embodiment 1:

[0045] A color-controllable monolithic LED (the schematic structural view of the cross-section is as shown in Figure 1 and the top view is as shown in Figure 2 ) comprises, in sequence and stacked, an Si substrate 10, a metal bonding layer 20, a first insulating layer 30, a mirror metal layer 40, a first p-type GaN layer 50, a first AlGaN electron blocking layer 60, a first InGaN / GaN multi-quantum well layer 70, an n-type GaN layer 80, a second InGaN / GaN multi-quantum well layer 90, a second AlGaN electron blocking layer 100, a second p-type GaN layer 110, a transparent current diffusion layer 120 and a second insulating layer 130, and further comprises a first p electrode 140, an n electrode 150 and a second p electrode 160;

[0046] The first p electrode 140 sequentially penetrates through the second insulating layer 130, the transparent current diffusion layer 120, the second p-type GaN layer 110, the second AlGaN electron blocking layer 100, the second InGaN / GaN multi-quantum well layer 90, the n-type GaN layer 80, the first InGaN / GaN multi-quantum well layer 70 and the first electron blocking layer 60, and its bottom forms an ohmic contact with the first p-type GaN layer 50;

[0047] The n - electrode 150 sequentially penetrates through the second insulating layer 130, the transparent current - spreading layer 120, the second p - type GaN layer 110, the second AlGaN electron - blocking layer 100, and the second InGaN / GaN multi - quantum well layer 90, and its bottom forms an ohmic contact with the n - type GaN layer 80;

[0048] The second p - electrode 160 sequentially penetrates through the second insulating layer 130 and the transparent current - spreading layer 120, and its bottom forms an ohmic contact with the second p - type GaN layer 110.

[0049] The preparation method of the above - mentioned color - controllable monolithic LED includes the following steps:

[0050] 1) By metal - organic chemical vapor deposition (MOCVD) method, grow a 1 - μm - thick AlGaN buffer layer, a 2 - μm - thick n - type GaN layer, a 50 - nm - thick first InGaN / GaN multi - quantum well layer (red - light quantum well layer), a 20 - nm - thick first AlGaN electron - blocking layer, and a 200 - nm - thick first p - type GaN layer on a Si substrate in sequence;

[0051] 2) Strip the Si substrate with a mixed solution of hydrofluoric acid, glacial acetic acid, and nitric acid, and strip the AlGaN buffer layer by ICP dry etching to expose the n - type GaN layer;

[0052] 3) Grow a 50 - nm - thick second InGaN / GaN multi - quantum well layer (blue - light quantum well layer), a 30 - nm - thick second AlGaN electron - blocking layer, and a 200 - nm - thick second p - type GaN layer on the n - type GaN layer, and then prepare a 10 - nm - thick transparent current - spreading layer (composed of a graphene layer and an ITO layer) on the second p - type GaN layer;

[0053] 4) Prepare a through - hole radially penetrating to the first p - type GaN layer and a through - hole radially penetrating to the n - type GaN layer by ICP dry etching;

[0054] 5) Grow a 400 - nm - thick second insulating layer (SiO2 layer) on the upper surface of the transparent current - spreading layer and the inner walls of the through - hole structure by plasma - enhanced chemical vapor deposition (PECVD) method, and the inner walls do not include the bottom surface of the through - hole;

[0055] 6) Set a groove - shaped structure penetrating to the second p - type GaN layer on the second insulating layer, and then deposit a first p - electrode (Cr / Pt / Au composite electrode), an n - electrode (Cr / Pt composite electrode), and a second p - electrode (Cr / Pt / Au composite electrode) in the through - hole structure and the groove - shaped structure;

[0056] 7) Deposit a 600-nm-thick mirror metal layer (formed by alternating 5 layers of 70-nm-thick SiO2 layers and 5 layers of 50-nm-thick TiO2 layers), a 400-nm-thick first insulating layer (SiO2 layer), and a 600-nm-thick metal bonding layer (Ni / Au composite layer) on the first p-type GaN layer. Then bond the metal bonding layer to a 400-μm-thick Si substrate. The bonding is carried out under the conditions of a pressure of 2 MPa and a temperature of 300 °C for 2 h, and then annealed at 200 °C for 30 min to obtain a color-controllable monolithic LED.

[0057] After testing, the color-controllable monolithic LED of this embodiment combined with circuit control can respectively achieve the emission of three-color lights, namely red light, blue light, and purple light, with good color uniformity.

[0058] Example 2:

[0059] A color-controllable monolithic LED, and its preparation method includes the following steps:

[0060] 1) Sequentially grow a 1-μm-thick AlGaN buffer layer, a 2-μm-thick n-type GaN layer, a 50-nm-thick first InGaN / GaN multiple quantum well layer (yellow light quantum well layer), a 20-nm-thick first AlGaN electron blocking layer, and a 200-nm-thick first p-type GaN layer on the Si substrate by metalorganic chemical vapor deposition (MOCVD);

[0061] 2) Strip the Si substrate with a mixed solution of hydrofluoric acid, glacial acetic acid, and nitric acid, and strip the AlGaN buffer layer by ICP dry etching to expose the n-type GaN layer;

[0062] 3) Grow a 50-nm-thick second InGaN / GaN multiple quantum well layer (blue light quantum well layer), a 30-nm-thick second AlGaN electron blocking layer, and a 200-nm-thick second p-type GaN layer on the n-type GaN layer;

[0063] 4) Deposit a 600-nm-thick mirror metal layer (formed by alternating 5 layers of 70-nm-thick SiO2 layers and 5 layers of 50-nm-thick TiO2 layers) and a 400-nm-thick first insulating layer (SiO2 layer) on the second p-type GaN layer;

[0064] 5) Prepare a through hole radially penetrating to the n-type GaN layer by ICP dry etching, and deposit an n electrode layer thereon;

[0065] 6) Prepare a 600-nm-thick metal bonding layer (Ni / Au composite layer) on the n electrode layer, and then bond the metal bonding layer to a 400-μm-thick Si substrate. The bonding is carried out under the conditions of a pressure of 2 MPa and a temperature of 300 °C for 2 h, and then annealed at 200 °C for 30 min;

[0066] 7) After being flipped by 180°, mesa structures that radially penetrate through to the second p-type GaN layer are prepared by ICP dry etching, and on this basis, a 10-nm-thick transparent current diffusion layer (composed of a graphene layer and an ITO layer) and a 400-nm-thick second insulating layer (SiO2 layer) are deposited.

[0067] 8) A groove-shaped structure that penetrates through to the second p-type GaN layer and the first p-type GaN layer is formed on the second insulating layer, and then a first p electrode (Cr / Pt / Au composite electrode) and a second p electrode (Cr / Pt / Au composite electrode) are deposited in the groove-shaped structure, thus obtaining a color-controllable monolithic LED.

[0068] After testing, the color-controllable monolithic LED of this embodiment, combined with circuit control, can respectively achieve the emission of three-color lights, namely yellow light, blue light, and white light, with good color uniformity. Compared with traditional laterally connected LEDs, its white light emission efficiency in the color temperature range of 3000K to 8000K is increased by 5%.

[0069] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A color-controllable monolithic LED, characterized in that, The composition includes a substrate, a metal bonding layer, a first insulating layer, a mirror metal layer, a first p-type GaN layer, a first AlGaN electron blocking layer, a first InGaN / GaN multi-quantum well layer, an n-type GaN layer, a second InGaN / GaN multi-quantum well layer, a second AlGaN electron blocking layer, a second p-type GaN layer, a transparent current diffusion layer and a second insulating layer, which are sequentially stacked. It also includes a first p electrode, an n electrode and a second p electrode; the first p electrode forms an ohmic contact with the first p-type GaN layer; the n electrode forms an ohmic contact with the n-type GaN layer; the second p electrode forms an ohmic contact with the second p-type GaN layer; each of the first InGaN / GaN multi-quantum well layer and the second InGaN / GaN multi-quantum well layer is independently one of a red light quantum well layer, a green light quantum well layer, a blue light quantum well layer, and a yellow light quantum well layer; the first insulating layer is a SiO2 layer with a thickness of 100 nm to 2000 nm; the second insulating layer is a SiO2 layer with a thickness of 100 nm to 2000 nm; the transparent current diffusion layer is one of a transparent In oxide conductive film, a transparent Sb oxide conductive film, a transparent Zn oxide conductive film, and a transparent Sn oxide conductive film, with a thickness of 10 nm to 800 nm.

2. The color-controllable monolithic LED according to claim 1, wherein: The substrate is a Si substrate with a thickness of 50 μm to 500 μm; the composition of the metal bonding layer is at least one of Ni, Au, Sn, and Ti, with a thickness of 0.5 μm to 5 μm.

3. The color-controllable monolithic LED according to claim 1 or 2, characterized in that: The composition of the mirror metal layer includes a plurality of SiO2 layers and a plurality of TiO2 layers arranged alternately, with a thickness of 0.5 μm to 4 μm.

4. The color-controllable single-chip LED according to claim 1 or 2, characterized in that: The thickness of the first p-type GaN layer is 10 nm to 300 nm; the thickness of the second p-type GaN layer is 10 nm to 300 nm.

5. The color-controllable monolithic LED according to claim 1 or 2, characterized in that: The thickness of the first AlGaN electron blocking layer is 20 nm to 40 nm; the thickness of the second AlGaN electron blocking layer is 20 nm to 40 nm; the thickness of the first InGaN / GaN multi-quantum well layer is 20 nm to 100 nm; the thickness of the second InGaN / GaN multi-quantum well layer is 20 nm to 100 nm.

6. The color-controllable monolithic LED according to claim 1 or 2, characterized in that: The thickness of the n-type GaN layer is 0.5 μm to 5 μm.

7. The color-controllable monolithic LED according to claim 1 or 2, characterized in that: The composition of the first p electrode is at least one of Cr, Pt, and Au; the composition of the n electrode is at least one of Cr, Pt, and Au; The composition of the second p electrode is at least one of Cr, Pt, and Au.

8. The preparation method of the color-controllable monolithic LED according to any one of claims 1 to 7, characterized in that It includes the following steps: 1) A buffer layer, an n-type GaN layer, a first InGaN / GaN multi-quantum well layer, a first AlGaN electron blocking layer and a first p-type GaN layer are sequentially grown on an epitaxial substrate. 2) The epitaxial substrate and the buffer layer are peeled off to expose the n-type GaN layer. 3) A second InGaN / GaN multi-quantum well layer, a second AlGaN electron blocking layer, and a second p-type GaN layer are grown on the n-type GaN layer, and then a transparent current diffusion layer is fabricated on the second p-type GaN layer. 4) Prepare vias that radially penetrate through the first p-type GaN layer and vias that radially penetrate through the n-type GaN layer; 5) Grow a second insulating layer on the upper surface of the transparent current diffusion layer and on the inner walls of the via structure, where the inner walls do not include the bottom surface of the vias; 6) Provide a groove-like structure on the second insulating layer that penetrates through to the second p-type GaN layer, and then deposit a first p-electrode, an n-electrode, and a second p-electrode in the via structure and the groove-like structure; 7) Deposit a mirror metal layer, a first insulating layer, and a metal bonding layer on the first p-type GaN layer, and then bond the metal bonding layer to the substrate to obtain a color-controllable monolithic LED.

9. A light source, characterized in that, The composition includes the color-controllable monolithic LED according to any one of claims 1 to 7.

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