Composite substrate, optoelectronic device and preparation method thereof

Abstract

A composite substrate (10), a photoelectric device, and a preparation method thereof. The composite substrate (10) comprises a substrate (11) and a nano-diamond structure (12) located on the substrate (11); the nano-diamond structure (12) comprises a plurality of nano-diamond protrusions (121) arranged at intervals, with a gap (122) provided between two adjacent nano-diamond protrusions (121). The photoelectric device comprises the composite substrate (10), and further comprises a first semiconductor layer (30), an active layer (40), and a second semiconductor layer (50) stacked on the composite substrate; the first semiconductor layer (30) comprises a protrusion (31) and a flat portion (32) stacked in sequence along a vertical direction, the protrusion (31) being in the gap (122) and corresponding one-to-one with the gap (122), and the flat portion (32) being located on the protrusion (31) and the nano-diamond structure (12). The preparation method of the photoelectric device is used for manufacturing the photoelectric device. The present application provides a layer of nano-diamond structure (12) in the composite substrate (10), thereby effectively avoiding absorption of UV light emitted by the active layer (40), thereby achieving the beneficial effect of significantly improving the light extraction efficiency of the UV LED.

Description

Technical Field

[0001] The present application relates to the field of semiconductors, and in particular to a composite substrate, an optoelectronic device, and a method for preparing the same. Background Art

[0002] In recent years, LEDs have become one of the most sought-after light source technologies. LEDs are characterized by their compact size, low current, and low voltage operation, which saves energy. Furthermore, they offer numerous advantages, including robust structure, strong shock and vibration resistance, and an extremely long lifespan. In the ultraviolet region, AlGaN-based multi-quantum well UV-LEDs have demonstrated significant advantages, becoming a hot topic in the development of ultraviolet optoelectronic devices. AlGaN-based multi-quantum well UV-LEDs have broad application prospects. Ultraviolet light has significant applications in screen printing, polymer curing, environmental protection, air and water purification, medical and biomedical sciences, white light illumination, military exploration, and secure space communications.

[0003] Due to the limited hole injection efficiency of the p-type AlGaN layer, it is difficult to form a good ohmic contact. Therefore, a p-GaN layer is often used on the p-type layer side to make a p-type ohmic contact to improve the hole injection efficiency of the p-type layer. However, due to the strong absorption and low reflectivity of the p-GaN layer to ultraviolet light (200nm-365nm), the light radiated from the quantum well to the p-type layer side is absorbed by the p-GaN layer and cannot be extracted, resulting in low light extraction efficiency. Most of the light that is not extracted is absorbed and converted into heat, causing the device temperature to rise, seriously affecting the reliability of the device.

[0004] Therefore, how to avoid the severe absorption of short-wavelength UV light by the P-type layer and improve light extraction efficiency remains a difficult problem that needs to be solved urgently. Summary of the Invention

[0005] The present application provides a composite substrate, an optoelectronic device, and a method for preparing the same, which can effectively avoid absorbing UV light emitted by an active layer, thereby achieving the beneficial effect of significantly improving the light extraction efficiency of UV LEDs.

[0006] To achieve the above-mentioned object, according to a first aspect of an embodiment of the present application, a composite substrate is provided. The composite substrate comprises a substrate and a nanodiamond structure located on the substrate;

[0007] The nano-diamond structure includes a plurality of nano-diamond protrusions spaced apart in a horizontal direction, and a gap is provided between two adjacent nano-diamond protrusions.

[0008] Optionally, the nano-diamond protrusions are nano-scale diamond grains, and the particle size of the nano-scale diamond grains is less than or equal to 200 nm.

[0009] Optionally, the material of the nano-diamond structure is boron-doped diamond material.

[0010] Optionally, the nanodiamond structure is made of undoped semiconductor material.

[0011] According to a second aspect of the embodiments of the present application, a photoelectric device is provided. The photoelectric device includes:

[0012] The composite substrate as described above;

[0013] a first semiconductor layer, an active layer, and a second semiconductor layer stacked on the composite substrate, wherein the first semiconductor layer and the second semiconductor layer have opposite conductivity types, and the first semiconductor layer and the nanodiamond structure have the same conductivity type;

[0014] The first semiconductor layer includes a raised portion and a flat portion stacked in sequence along the vertical direction, the raised portion is in the gap, and the raised portion corresponds to the gap one by one, the flat portion is located on the raised portion and the nano-diamond structure, and the side of the flat portion away from the nano-diamond structure is a plane.

[0015] Optionally, the materials of the first semiconductor layer and the second semiconductor layer are both wide bandgap semiconductor materials, and the bandgap width of the wide bandgap semiconductor materials is greater than 2.0 eV.

[0016] Optionally, the photoelectric device further includes a first electrode and a second electrode;

[0017] A groove is formed on the second semiconductor layer, the groove passes through the second semiconductor layer and the active layer, and at least a portion of the first semiconductor layer remains below the groove;

[0018] The first electrode is located at the bottom of the groove;

[0019] The second electrode is disposed on the second semiconductor layer.

[0020] Optionally, the optoelectronic device further includes a first electrode and a second electrode; the first electrode is disposed below the composite substrate; and the second electrode is disposed on the second semiconductor layer.

[0021] Optionally, the second electrode contains a reflector material.

[0022] According to a third aspect of the embodiments of the present application, a method for preparing a photoelectric device is provided. The method for preparing a photoelectric device comprises the following steps:

[0023] S1: forming a composite substrate, comprising: providing a substrate, and forming a nano-diamond structure on the substrate, wherein the nano-diamond structure comprises a plurality of nano-diamond protrusions spaced apart in a horizontal direction, with a gap being provided between two adjacent nano-diamond protrusions;

[0024] S2: forming a first semiconductor layer on the composite substrate, epitaxially growing the first semiconductor layer using the nano-diamond protrusions as a mask, wherein the first semiconductor layer includes a protrusion and a flat portion stacked in sequence along a vertical direction, wherein the protrusions are formed within the gaps and correspond one-to-one with the gaps, the flat portion is formed on the upper surface of the nano-diamond structure, and a flat portion of the first semiconductor layer is formed on the protrusions, wherein a surface of the flat portion away from the nano-diamond structure is a plane; the first semiconductor layer and the nano-diamond structure have the same conductivity type;

[0025] S3: forming an active layer and a second semiconductor layer in sequence on the first semiconductor layer, wherein the conductivity type of the second semiconductor layer is opposite to that of the first semiconductor layer.

[0026] Optionally, the method for manufacturing the optoelectronic device further includes:

[0027] S4: etching the second semiconductor layer to form a groove, wherein the groove penetrates the second semiconductor layer and the active layer, and at least a portion of the first semiconductor layer remains below the groove;

[0028] S5: forming a first electrode at the bottom of the groove; and forming a second electrode on the second semiconductor layer.

[0029] Optionally, the method for manufacturing the optoelectronic device further includes:

[0030] S4: thinning the composite substrate;

[0031] S5: forming a first electrode below the composite substrate; and forming a second electrode on the second semiconductor layer.

[0032] The composite substrate, optoelectronic device, and preparation method of the present application, by providing a layer of nano-diamond structure on the substrate and then forming the entire epitaxial structure of the optoelectronic device on the nano-diamond structure, can effectively avoid absorbing UV light emitted by the active layer, thereby achieving the beneficial effect of significantly improving the light extraction efficiency of the UV LED. This is because the nano-diamond structure has a very weak absorption effect on light of the entire wavelength band, which reduces the problem of light absorption and can effectively improve the light extraction efficiency of LEDs, especially UV LEDs; secondly, the band gap width of diamond is large and the reflection effect on electrons is strong, which can reduce electron leakage and increase brightness; thirdly, the nano-diamond structure is easy to dope, has a high hole concentration, and is easy to prepare ohmic contacts. In addition, the present application can improve the overall heat dissipation effect by providing a specific structure of the composite substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the cross-sectional structure of the composite substrate of Example 1 of the present application.

[0034] Figure 2 It is a schematic diagram of the cross-sectional structure of the optoelectronic device of Example 1 of the present application.

[0035] Figure 3(a)-Figure 3(e) This is a process flow chart of the method for preparing the optoelectronic device of Example 1 of the present application.

[0036] Figure 4 It is a schematic diagram of the cross-sectional structure of the optoelectronic device of Example 2 of the present application.

[0037] Figure 5(a)-Figure 5(b) This is a process flow chart of the method for preparing the optoelectronic device of Example 2 of the present application. DETAILED DESCRIPTION

[0038] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

[0039] Example 1

[0040] Combine Figure 1 It is understood that this embodiment provides a composite substrate 10. The composite substrate 10 includes a substrate 11 and a nanodiamond structure 12 located on the substrate 11; wherein the nanodiamond structure 12 includes a plurality of nanodiamond protrusions 121 spaced apart along a horizontal direction X, with a gap 122 between two adjacent nanodiamond protrusions 121.

[0041] The material of the nano-diamond structure 12 is a boron-doped diamond material, but is not limited thereto. In other embodiments, the nano-diamond structure 12 may also be a non-doped semiconductor material.

[0042] The nano-diamond protrusions 121 are nano-scale diamond grains, and the particle size of the nano-scale diamond grains is less than or equal to 200 nm.

[0043] In this embodiment, the nano-diamond structure 12 is formed by a CVD process, which can directly form a plurality of nano-scale diamond grains spaced apart from each other.

[0044] Combine Figure 2 It is understood that this embodiment also provides an optoelectronic device 1. The optoelectronic device 1 includes: the composite substrate 10 as described above, a first semiconductor layer 30, an active layer 40, and a second semiconductor layer 50 stacked on the composite substrate 10. The first semiconductor layer 30 and the second semiconductor layer 50 have opposite conductivity types, and the first semiconductor layer 30 and the nanodiamond structure 12 have the same conductivity type.

[0045] Specifically, the first semiconductor layer 30 includes a raised portion 31 and a flat portion 32 stacked in sequence along the vertical direction H. The raised portion 31 is in the gap 122, and the raised portion 31 corresponds to the gap 122 one by one. The flat portion 32 is located on the raised portion 31 and the nano-diamond structure 12, and the side of the flat portion 32 away from the nano-diamond structure 12 is a plane.

[0046] The first semiconductor layer 30 and the second semiconductor layer 50 are both made of wide-bandgap semiconductor materials with a bandgap greater than 2.0 eV. Specifically, the wide-bandgap semiconductor materials are gallium nitride-based materials, boron nitride, or indium tin oxide (ITO), as long as they can be combined with the nanodiamond structure 12.

[0047] The active layer 40 is a multi-quantum well structure.

[0048] In this embodiment, the optoelectronic device 1 further includes a first electrode 81 and a second electrode 82 .

[0049] The second semiconductor layer 50 is provided with a groove 70 which penetrates the second semiconductor layer 50 and the active layer 40 , and at least a portion of the first semiconductor layer 30 is left below the groove 70 . The first electrode 81 is located at the bottom of the groove 70 and is connected to the first semiconductor layer 30 .

[0050] The second electrode 82 is disposed on the second semiconductor layer 50 and connected to the second semiconductor layer 50 .

[0051] Figure 3(a)-Figure 3(e): is a process flow chart of the method for preparing the optoelectronic device of Example 1 of the present application. The method is used to make the optoelectronic device described above. The method for preparing the optoelectronic device comprises the following steps:

[0052] Step 100: forming a composite substrate, including: providing a substrate, and forming a nano-diamond structure on the substrate, wherein the nano-diamond structure includes a plurality of nano-diamond protrusions spaced apart in a horizontal direction, with a gap between two adjacent nano-diamond protrusions;

[0053] Step 200: forming a first semiconductor layer on the composite substrate, epitaxially growing the first semiconductor layer using the nanodiamond protrusions as a mask, wherein the first semiconductor layer includes a protrusion and a flat portion stacked in sequence along a vertical direction, wherein the protrusions are formed within the gaps and correspond one-to-one with the gaps, the flat portion is formed on the upper surface of the nanodiamond structure, and a flat portion of the first semiconductor layer is formed on the protrusions, wherein a surface of the flat portion away from the nanodiamond structure is a plane; the first semiconductor layer and the nanodiamond structure have the same conductivity type;

[0054] Step 300: forming an active layer and a second semiconductor layer in sequence on the first semiconductor layer, wherein the conductivity type of the second semiconductor layer is opposite to that of the first semiconductor layer;

[0055] Step 400: etching the second semiconductor layer to form a groove, wherein the groove penetrates the second semiconductor layer and the active layer, and at least a portion of the first semiconductor layer remains below the groove;

[0056] Step 500: forming a first electrode at the bottom of the groove; and forming a second electrode on the second semiconductor layer.

[0057] Specifically, as shown in Figure 3(a), in step 100, a composite substrate 10 is formed, including: providing a substrate 11, forming a nano-diamond structure 12 on the substrate 11 by a CVD process, the nano-diamond structure 12 including a plurality of nano-diamond protrusions 121 spaced apart in a horizontal direction X, and a gap 122 is provided between two adjacent nano-diamond protrusions 121.

[0058] In step 200, as shown in FIG3(b), a first semiconductor layer 30 is formed on the composite substrate 10. The first semiconductor layer 30 is epitaxially grown using the nano-diamond protrusions 121 as a mask. The first semiconductor layer 30 includes a protrusion 31 and a flat portion 32 stacked in sequence along the vertical direction H. The protrusion 31 is formed in the gap 122 and corresponds one-to-one with the gap 122. The flat portion 32 is formed on the upper surface of the nano-diamond structure 12 and the flat portion 32 of the first semiconductor layer 30 is formed on the protrusion 31. The surface of the flat portion 32 away from the nano-diamond structure 12 is a plane. The first semiconductor layer 30 and the nano-diamond structure 12 have the same conductivity type:

[0059] In step 300 , as shown in FIG. 3( c ), an active layer 40 and a second semiconductor layer 50 are sequentially formed on the first semiconductor layer 30 . The conductivity type of the second semiconductor layer 50 is opposite to that of the first semiconductor layer 30 .

[0060] In step 400 , as shown in FIG. 3( d ), a groove 70 is formed on the second semiconductor layer 50 by etching. The groove 70 penetrates the second semiconductor layer 50 and the active layer 40 , and at least a portion of the first semiconductor layer 30 remains below the groove 70 .

[0061] In step 500 , as shown in FIG. 3( e ), a first electrode 81 is formed at the bottom of the groove 70 ; and a second electrode 82 is formed on the second semiconductor layer 50 .

[0062] This embodiment can improve the heat dissipation effect by setting a specific structure of the composite substrate. Furthermore, the composite substrate, optoelectronic device and preparation method of this embodiment, by setting a layer of nano-diamond structure on the substrate and then forming the entire epitaxial structure of the optoelectronic device on the nano-diamond structure, can effectively avoid absorbing UV light emitted by the active layer, thereby achieving the beneficial effect of significantly improving the light extraction efficiency of the UV LED. This is because the nano-diamond structure has a very weak absorption effect on light of the entire wavelength band, which reduces the problem of light absorption and can effectively improve the light extraction efficiency of LEDs, especially UV LEDs; secondly, the band gap width of diamond is large and the reflection effect on electrons is strong, which can reduce electron leakage and improve brightness; thirdly, the nano-diamond structure is easy to dope, has a high hole concentration, and is easy to prepare ohmic contacts.

[0063] Example 2

[0064] like Figure 4As shown, this embodiment provides a photoelectric device 1, the structure of which is basically the same as that of the photoelectric device 1 in Example 1, except that: the setting positions of the first electrode 81 and the second electrode 82 of the photoelectric device 1 in this embodiment are different from the setting positions of the first electrode 81 and the second electrode 82 in Example 1. Specifically, the first electrode 81 is set below the composite substrate 10; the second electrode 82 is set on the second semiconductor layer 50.

[0065] Furthermore, the orthographic projection of the second electrode 82 on the second semiconductor layer 50 overlaps the outer periphery of the second semiconductor layer 50. The second electrode 82 contains a reflector material. Specifically, the reflector material is a reflective material such as aluminum, silver, titanium, or magnesium fluoride.

[0066] like Figure 5(a)-Figure 5(b) As shown, another aspect of this embodiment further provides a method for preparing a photoelectric device, which is used to prepare the above-mentioned photoelectric device. The steps of the photoelectric device preparation method are basically the same as those of the photoelectric device preparation method of Example 1, except that after completing step S300, the photoelectric device preparation method further includes:

[0067] Step 400: As shown in FIG5(a), thinning the composite substrate 10;

[0068] Step 500 : As shown in FIG. 5( b ), a first electrode 81 is formed below the composite substrate 10 ; and a second electrode 82 is formed on the second semiconductor layer 50 .

[0069] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A photoelectric device, characterized in that: The optoelectronic device comprises: A composite substrate comprising a substrate and a nanodiamond structure located on the substrate; The nano-diamond structure comprises a plurality of nano-diamond protrusions spaced apart in a horizontal direction, with a gap being provided between two adjacent nano-diamond protrusions; Wherein, the material of the nano-diamond structure is boron-doped diamond material; Wherein, the nano-diamond structure is used to avoid absorbing UV light emitted by the active layer in the optoelectronic device; A first semiconductor layer, an active layer, and a second semiconductor layer are stacked on the composite substrate, wherein the first semiconductor layer and the second semiconductor layer have opposite conductivity types, and the first semiconductor layer and the nanodiamond structure have the same conductivity type; the first semiconductor layer and the second semiconductor layer are made of gallium nitride-based materials, boron nitride, or indium tin oxide; The first semiconductor layer includes a raised portion and a flat portion stacked in sequence along the vertical direction, the raised portion is in the gap, and the raised portion corresponds to the gap one by one, the flat portion is located on the raised portion and the nano-diamond structure, and the side of the flat portion away from the nano-diamond structure is a plane.

2. The optoelectronic device according to claim 1, wherein The materials of the first semiconductor layer and the second semiconductor layer are both wide bandgap semiconductor materials, and the bandgap width of the wide bandgap semiconductor materials is greater than 2.0 eV.

3. The optoelectronic device according to claim 1, wherein The optoelectronic device further comprises a first electrode and a second electrode; A groove is formed on the second semiconductor layer, the groove passes through the second semiconductor layer and the active layer, and at least a portion of the first semiconductor layer remains below the groove; The first electrode is located at the bottom of the groove; The second electrode is disposed on the second semiconductor layer.

4. The optoelectronic device according to claim 1, wherein The optoelectronic device further includes a first electrode and a second electrode; the first electrode is disposed below the composite substrate; and the second electrode is disposed on the second semiconductor layer.

5. The optoelectronic device according to claim 4, wherein The second electrode contains a reflective mirror material.

6. A method for manufacturing a photoelectric device, characterized in that: The method for manufacturing the optoelectronic device comprises the following steps: S1: forming a composite substrate, comprising: providing a substrate, and forming a nano-diamond structure on the substrate, wherein the nano-diamond structure comprises a plurality of nano-diamond protrusions spaced apart in a horizontal direction, with a gap being provided between two adjacent nano-diamond protrusions; S2: forming a first semiconductor layer on the composite substrate, epitaxially growing the first semiconductor layer using the nano-diamond protrusions as a mask, wherein the first semiconductor layer includes a protrusion and a flat portion stacked in sequence along a vertical direction, wherein the protrusions are formed within the gaps and correspond one-to-one with the gaps, the flat portion is formed on the upper surface of the nano-diamond structure, and a flat portion of the first semiconductor layer is formed on the protrusions, wherein a surface of the flat portion away from the nano-diamond structure is a plane; the first semiconductor layer and the nano-diamond structure have the same conductivity type; S3: forming an active layer and a second semiconductor layer in sequence on the first semiconductor layer, wherein the conductivity type of the second semiconductor layer is opposite to that of the first semiconductor layer; Wherein, the material of the nano-diamond structure is boron-doped diamond material; Wherein, the nano-diamond structure is used to avoid absorbing UV light emitted by the active layer in the optoelectronic device; The materials of the first semiconductor layer and the second semiconductor layer are gallium nitride-based materials, boron nitride, or indium tin oxide.

7. The method for manufacturing a photoelectric device according to claim 6, wherein: The method for manufacturing the optoelectronic device further includes: S4: etching the second semiconductor layer to form a groove, wherein the groove penetrates the second semiconductor layer and the active layer, and at least a portion of the first semiconductor layer remains below the groove; S5: forming a first electrode at the bottom of the groove; and forming a second electrode on the second semiconductor layer.

8. The method for manufacturing a photovoltaic device according to claim 6, wherein: The method for manufacturing the optoelectronic device further includes: S4: thinning the composite substrate; S5: forming a first electrode below the composite substrate; and forming a second electrode on the second semiconductor layer.

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