Optoelectronic device and its manufacturing method

Abstract

The present application provides an optoelectronic device and a preparation method thereof. The optoelectronic device includes a first semiconductor layer, an active layer, and a second semiconductor layer which are sequentially stacked. The first semiconductor layer and the second semiconductor layer have opposite conductivity types. A layer of nanodiamond structure is provided in the second semiconductor layer, and the nanodiamond structure has the same conductivity type as the second semiconductor layer. The preparation method of the optoelectronic device is used to fabricate the optoelectronic device. By providing a layer of nanodiamond structure in the second semiconductor layer, the present application can effectively avoid absorbing the UV light emitted by the active layer, achieving the beneficial effect of greatly 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 photoelectric device and a method for preparing the same. Background Art

[0002] In recent years, LED has gradually become one of the most valued light source technologies. On the one hand, LED has the characteristics of small size; on the other hand, LED has the power-saving characteristics of low current and low voltage drive; at the same time, it also has many advantages such as strong structure, strong impact and vibration resistance, and ultra-long life. Especially in the ultraviolet region, AlGaN-based multi-quantum well ultraviolet LED has shown great advantages and has become one of the hot spots in the development of ultraviolet optoelectronic devices. AlGaN-based multi-quantum well UV-LED devices have broad application prospects. Ultraviolet light has great application value in screen printing, polymer curing, environmental protection, air and water purification, medical and biomedicine, white light lighting, military detection, space confidential communication and other fields.

[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 of ultraviolet light (200nm-365nm) and low reflectivity of the p-GaN layer, 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 the light extraction efficiency is still a difficult problem that needs to be solved urgently. Summary of the invention

[0005] The present application provides 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 object, according to a first aspect of an embodiment of the present application, a photoelectric device is provided. The photoelectric device comprises a first semiconductor layer, an active layer, and a second semiconductor layer stacked in sequence, wherein the first semiconductor layer and the second semiconductor layer have opposite conductivity types;

[0007] A layer of nano-diamond structure is disposed in the second semiconductor layer, and the nano-diamond structure has the same conductivity type as the second semiconductor layer.

[0008] Optionally, the second semiconductor layer includes a first flat portion, a convex portion, and a second flat portion that are stacked in sequence in the vertical direction. The first flat portion is stacked on the active layer, the nanodiamond structure is disposed on the first flat portion, and includes a plurality of spaced nanodiamond protrusions. There is a gap between two adjacent nanodiamond protrusions. The convex portion of the second semiconductor layer is located in the gap. The second flat portion is disposed on the convex portion and the nanodiamond structure, and one side of the second flat portion away from the convex portion is a plane.

[0009] Optionally, the nanodiamond structure is formed by a CVD process.

[0010] Optionally, the nanodiamond protrusions are nanoscale diamond grains, and the particle size of the nanoscale diamond grains is less than or equal to 200 nm.

[0011] Optionally, the active layer is a multi-quantum well structure.

[0012] 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.

[0013] Optionally, the optoelectronic device further includes a substrate and a buffer layer. The buffer layer is disposed between the substrate and the first semiconductor layer in the vertical direction.

[0014] Optionally, the optoelectronic device further includes a first electrode and a second electrode;

[0015] A groove is formed in the second semiconductor layer, the groove penetrates through the second semiconductor layer and the active layer, and at least a part of the first semiconductor layer is left below the groove;

[0016] The first electrode is located at the bottom of the groove and is connected to the first semiconductor layer;

[0017] The second electrode is disposed on the second semiconductor layer and is connected to the second semiconductor layer.

[0018] Optionally, the optoelectronic device further includes a first electrode and a second electrode; the first electrode is disposed below the first semiconductor layer; the second electrode is disposed on the second semiconductor layer.

[0019] Optionally, the second electrode contains a mirror material.

[0020] According to the second aspect of the embodiments of the present application, a method for manufacturing an optoelectronic device is provided. The method for manufacturing the optoelectronic device includes the following steps:

[0021] S1: Form a first semiconductor layer and an active layer on the substrate in sequence;

[0022] S2: Form a second semiconductor layer and a nanodiamond structure on the active layer, wherein the nanodiamond structure is located in the second semiconductor layer; the conductivity type of the second semiconductor layer is opposite to that of the first semiconductor layer, and the conductivity type of the nanodiamond structure is the same as that of the second semiconductor layer.

[0023] Optionally, the second semiconductor layer includes a first flat portion, a convex portion, and a second flat portion stacked in sequence in the vertical direction. In step S2, it includes:

[0024] Through the first epitaxial growth, form the first flat portion of the second semiconductor layer on the active layer, form a nanodiamond structure on the first flat portion of the second semiconductor layer, the nanodiamond structure includes a plurality of spaced nanodiamond protrusions, and a gap is formed between two adjacent nanodiamond protrusions; continue the second epitaxial growth of the second semiconductor layer with the nanodiamond protrusions as a mask, form the convex portion of the second semiconductor layer in the gap, form the second flat portion of the second semiconductor layer on the upper surface of the nanodiamond structure and the convex portion, and the side of the second flat portion away from the convex portion is a plane.

[0025] Optionally, in step S1, the first semiconductor layer and the active layer are formed by MOCVD process;

[0026] In step S2, the second semiconductor layer is formed by MOCVD process; the nanodiamond structure is formed by CVD process.

[0027] Optionally, step S1 includes:

[0028] S11: Form a buffer layer on the substrate;

[0029] S12: Form the first semiconductor layer and the active layer on the buffer layer in sequence.

[0030] Optionally, the method for preparing the optoelectronic device further includes:

[0031] S3: Form an etching groove on the second semiconductor layer, the groove penetrates through the second semiconductor layer and the active layer, and at least a part of the first semiconductor layer is left below the groove;

[0032] S4: Form a first electrode at the bottom of the groove; form a second electrode on the second semiconductor layer.

[0033] Optionally, the method for preparing the optoelectronic device further includes:

[0034] S3: Strip the substrate;

[0035] S4: Form a first electrode under the first semiconductor layer; form a second electrode on the second semiconductor layer.

[0036] For the optoelectronic device and its manufacturing method of the present application, by providing a layer of nanodiamond structure in the second semiconductor layer, it can effectively avoid absorbing the UV light emitted by the active layer, achieving the beneficial effect of greatly improving the light extraction efficiency of the UV LED. This is because the nanodiamond structure has a weak absorption effect on light in the entire wavelength band, reducing the light absorption problem, and can effectively improve the light extraction efficiency of the LED, especially the UV LED; secondly, diamond has a relatively large bandgap and a strong reflection effect on electrons, which can reduce electron leakage and increase the brightness, that is, improve the light output efficiency; thirdly, the nanodiamond structure is easy to dope, has a relatively high hole concentration, and is easy to fabricate ohmic contacts. Description of the Drawings

[0037] Figure 1 is a schematic cross-sectional structure diagram of the optoelectronic device of Embodiment 1 of the present application.

[0038] Figures 2(a)-2(f) is a process flow chart of the manufacturing method of the optoelectronic device of Embodiment 1 of the present application.

[0039] Figure 3 is a schematic cross-sectional structure diagram of the optoelectronic device of Embodiment 2 of the present application.

[0040] Figures 4(a)-4(b) is a process flow chart of the manufacturing method of the optoelectronic device of Embodiment 2 of the present application. Detailed Description of the Embodiments

[0041] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0042] Embodiment 1

[0043] Combined with Figure 1 For understanding, this embodiment provides an optoelectronic device 1. The optoelectronic device 1 includes a first semiconductor layer 30, an active layer 40, and a second semiconductor layer 50 stacked in sequence. The first semiconductor layer 30 and the second semiconductor layer 50 have opposite conductivity types. Among them, a layer of nanodiamond structure 60 is provided in the second semiconductor layer 50, and the nanodiamond structure 60 has the same conductivity type as the second semiconductor layer 50.

[0044] Specifically, the second semiconductor layer 50 includes a first flat portion 51, a convex portion 52, and a second flat portion 53 that are sequentially stacked in the vertical direction H. The nanodiamond structure 60 includes a plurality of nanodiamond protrusions 61 that are spaced apart in the horizontal direction X, and a gap 62 is provided between two adjacent nanodiamond protrusions 61.

[0045] The first flat portion 51 is stacked on the active layer 40, and the nanodiamond structure 60 is disposed on the first flat portion 51. The convex portion 52 of the second semiconductor layer 50 is located in the gap 62, and the convex portion 52 of the second semiconductor layer 50 corresponds to the gap 62 one by one. The second flat portion 53 is disposed on the convex portion 52 and the nanodiamond structure 60, and one side of the second flat portion 53 away from the convex portion 52 is a plane.

[0046] The nanodiamond protrusion 61 is a nanoscale diamond crystal grain, and the particle size of the nanoscale diamond crystal grain is less than or equal to 200 nm.

[0047] In this embodiment, the nanodiamond structure 60 is formed by a CVD process. By the CVD process, a plurality of spaced nanoscale diamond crystal grains can be directly formed.

[0048] The materials of the first semiconductor layer 30 and the second semiconductor layer 50 are both wide-bandgap semiconductor materials, and the bandgap width of the wide-bandgap semiconductor materials is greater than 2.0 eV. Specifically, the wide-bandgap semiconductor material is a gallium nitride-based material, or boron nitride, or a material such as indium tin oxide (ITO).

[0049] The active layer 40 is a multi-quantum well structure.

[0050] In this embodiment, the optoelectronic device 1 further includes a substrate 10, a buffer layer 20, a first electrode 81, and a second electrode 82. The buffer layer 20 is disposed between the substrate 10 and the first semiconductor layer 30 in the vertical direction.

[0051] A groove 70 is formed in the second semiconductor layer 50, the groove 70 penetrates through the second semiconductor layer 50 and the active layer 40, and at least a part 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.

[0052] The second electrode 82 is disposed on the second semiconductor layer 50 and is connected to the second semiconductor layer 50.

[0053] Figures 2(a)-2(f) It is a process flow chart of the manufacturing method of the optoelectronic device of Embodiment 1 of the present application. This manufacturing method is used to manufacture the optoelectronic device as described above. The manufacturing method of the optoelectronic device includes the following steps:

[0054] Step 100: A first semiconductor layer and an active layer are sequentially formed on a substrate;

[0055] Step 200: A second semiconductor layer and a nanodiamond structure are formed on the active layer, wherein the nanodiamond structure is located in the second semiconductor layer; the second semiconductor layer has a conductivity type opposite to that of the first semiconductor layer, and the nanodiamond structure has the same conductivity type as the second semiconductor layer;

[0056] Step 300: An etching groove is formed on the second semiconductor layer, the groove penetrates through the second semiconductor layer and the active layer, and at least a part of the first semiconductor layer is left below the groove;

[0057] Step 400: A first electrode is formed at the bottom of the groove; a second electrode is formed on the second semiconductor layer.

[0058] Specifically, as shown in Fig. 2(a), in Step 100, the first semiconductor layer 30 and the active layer 40 are formed by MOCVD process, including:

[0059] S110: A buffer layer 20 is formed on the substrate 10;

[0060] S120: The first semiconductor layer 30 and the active layer 40 are sequentially formed on the buffer layer 20.

[0061] In Step 200, the second semiconductor layer 50 is formed by MOCVD process. The second semiconductor layer 50 includes a first flat portion 51, a convex portion 52, and a second flat portion 53 stacked in the vertical direction in sequence; the nanodiamond structure 60 is formed by CVD process. The nanodiamond structure 60 includes a plurality of nanodiamond protrusions 61 arranged at intervals in the horizontal direction X, and a gap 62 is formed between two adjacent nanodiamond protrusions 61. Specifically, it includes:

[0062] As shown in Fig. 2(b), through the first epitaxial growth, the first flat portion 51 of the second semiconductor layer 50 is formed on the active layer 40;

[0063] As shown in Fig. 2(c), the nanodiamond structure 60 is formed on the first flat portion 51 of the second semiconductor layer 50, that is, a plurality of spaced nanodiamond protrusions 61 are formed on the first flat portion 51 of the second semiconductor layer 50;

[0064] As shown in Fig. 2(d), using the nanodiamond protrusions 61 as a mask, the second semiconductor layer 50 is continuously epitaxially grown for the second time. Protrusions 52 of the second semiconductor layer 50 are formed within the gaps 62, and second flat portions 53 of the second semiconductor layer 50 are formed on the upper surface of the nanodiamond structure 60 and on the protrusions 52; the protrusions 52 of the second semiconductor layer 50 correspond to the gaps 62 one by one, and one side of the second flat portion 53 away from the protrusion 52 is a plane.

[0065] It should be noted that the first semiconductor layer 30, the active layer 40, and the second semiconductor layer 50 can be formed not only by the MOCVD (Metal-Organic Chemical Vapor Deposition) process but also by processes such as MBE (Molecular Beam Epitaxy).

[0066] In step 300, as shown in Fig. 2(e), grooves 70 are formed by etching on the second semiconductor layer 50. The grooves 70 penetrate through the second semiconductor layer 50 and the active layer 40, and at least a part of the first semiconductor layer 30 is left below the grooves 70.

[0067] In step 300, as shown in Fig. 2(f), a first electrode 81 is formed at the bottom of the grooves 70; a second electrode 82 is formed on the second semiconductor layer 50.

[0068] For the optoelectronic device and its manufacturing method of this embodiment, by providing a layer of nanodiamond structure in the second semiconductor layer, the absorption of the UV light emitted by the active layer can be effectively avoided, achieving the beneficial effect of greatly improving the light extraction efficiency of the UV LED. This is because the nanodiamond structure has a weak absorption effect on light in the entire wavelength range, reducing the light absorption problem, and can effectively improve the light extraction efficiency of the LED, especially the UV LED; secondly, diamond has a large bandgap width and a strong reflection effect on electrons, which can reduce electron leakage and improve the brightness, that is, improve the light output efficiency; thirdly, the nanodiamond structure is easy to dope, has a high hole concentration, and is easy to prepare ohmic contacts.

[0069] Embodiment 2

[0070] As Figure 3 shown, this embodiment provides an optoelectronic device 1. The structure of the optoelectronic device 1 is basically the same as that of the optoelectronic device 1 in Embodiment 1, and the difference lies in that: the optoelectronic device 1 in this embodiment does not include the substrate 10 and the buffer layer 20, and the setting positions of the first electrode 81 and the second electrode 82 are different from those of the first electrode 81 and the second electrode 82 in Embodiment 1. Specifically, the first electrode 81 is disposed below the first semiconductor layer 30; the second electrode 82 is disposed on the second semiconductor layer 50.

[0071] Furthermore, the positive projection of the second electrode 82 on the second semiconductor layer 50 overlaps with the outer peripheral edge of the second semiconductor layer 50. The second electrode 82 contains a mirror material to further improve the light-emitting efficiency of the device. Specifically, the mirror material is a material with a reflective effect such as aluminum, silver, titanium, etc.

[0072] As Figures 4(a)-4(b) shown, another aspect of this embodiment further provides a method for manufacturing an optoelectronic device for manufacturing the above optoelectronic device. The method for manufacturing this optoelectronic device is basically the same as the steps of the method for manufacturing the optoelectronic device in the embodiment, and the difference lies in that after completing step S200, the method for manufacturing the optoelectronic device further includes:

[0073] Step 300: As shown in FIG. 4(a), peel off the substrate, and when a buffer layer is formed, also peel off the buffer layer;

[0074] Step 400: As shown in FIG. 4(b), form a first electrode 81 under the first semiconductor layer 30; form a second electrode 82 on the second semiconductor layer 50.

[0075] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the scope of protection of the present application.

Claims

1. A optoelectronic device, the optoelectronic device includes a first semiconductor layer, an active layer, and a second semiconductor layer which are stacked in sequence, and the conductivity types of the first semiconductor layer and the second semiconductor layer are opposite. Characterized in that, A layer of nanodiamond structure is provided in the second semiconductor layer, and the conductivity type of the nanodiamond structure is the same as that of the second semiconductor layer; Wherein, the second semiconductor layer includes a first flat portion and a second flat portion which are stacked in sequence in the vertical direction, the first flat portion is stacked on the active layer, the nanodiamond structure is provided on the first flat portion, and the second flat portion is provided on the nanodiamond structure.

2. The optoelectronic device according to claim 1, Characterized in that, The second semiconductor layer includes a convex portion provided between the first flat portion and the second flat portion, the nanodiamond structure includes a plurality of nanodiamond protrusions arranged at intervals in the horizontal direction, a gap is provided between two adjacent nanodiamond protrusions, the convex portion of the second semiconductor layer is located in the gap, and the convex portion of the second semiconductor layer corresponds to the gap one by one, and one side of the second flat portion away from the convex portion is a plane.

3. The optoelectronic device according to claim 2, Characterized in that, The nanodiamond protrusion is a nanoscale diamond crystal grain, and the particle size of the nanoscale diamond crystal grain is less than or equal to 200 nm.

4. The optoelectronic device according to claim 1, Characterized in that, 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.

5. The optoelectronic device according to claim 1, Characterized in that, The optoelectronic device further includes a substrate and a buffer layer, and the buffer layer is provided between the substrate and the first semiconductor layer in the vertical direction.

6. The optoelectronic device according to claim 1, Characterized in that, The optoelectronic device further includes a first electrode and a second electrode; A groove is formed on the second semiconductor layer, the groove penetrates through the second semiconductor layer and the active layer, and at least a part of the first semiconductor layer is left below the groove; The first electrode is located at the bottom of the groove and is connected to the first semiconductor layer; The second electrode is provided on the second semiconductor layer and is connected to the second semiconductor layer.

7. The optoelectronic device according to claim 1, Characterized in that, The optoelectronic device further includes a first electrode and a second electrode; the first electrode is provided below the first semiconductor layer; the second electrode is provided on the second semiconductor layer.

8. The optoelectronic device according to claim 7, Characterized in that, The second electrode contains a mirror material.

9. A method for manufacturing an optoelectronic device, Characterized in that, The method for manufacturing the optoelectronic device includes the following steps: S1: Form a first semiconductor layer and an active layer on a substrate in sequence; S2: Form a second semiconductor layer and a nanodiamond structure on the active layer, wherein the nanodiamond structure is located in the second semiconductor layer; the second semiconductor layer has a conductivity type opposite to that of the first semiconductor layer, and the nanodiamond structure has the same conductivity type as the second semiconductor layer; Wherein, the second semiconductor layer includes a first flat portion and a second flat portion stacked in sequence in the vertical direction. The first flat portion is stacked on the active layer, the nanodiamond structure is disposed on the first flat portion, and the second flat portion is disposed on the nanodiamond structure.

10. The method for manufacturing an optoelectronic device according to claim 9, wherein the second semiconductor layer includes a convex portion disposed between the first flat portion and the second flat portion. In step S2, It includes: Through the first epitaxial growth, form the first flat portion of the second semiconductor layer on the active layer, and form the nanodiamond structure on the first flat portion of the second semiconductor layer. The nanodiamond structure includes a plurality of spaced nanodiamond protrusions, and a gap is formed between two adjacent nanodiamond protrusions; continue the second epitaxial growth of the second semiconductor layer with the nanodiamond protrusions as a mask, form the convex portion of the second semiconductor layer in the gap, and form the second flat portion of the second semiconductor layer on the upper surface of the nanodiamond structure and the convex portion; the convex portion of the second semiconductor layer corresponds to the gap one by one, and the side of the second flat portion away from the convex portion is a plane.

11. The method for manufacturing an optoelectronic device according to claim 9, in step S1 It includes: S11: Form a buffer layer on the substrate; S12: Sequentially form the first semiconductor layer and the active layer on the buffer layer.

12. The method for manufacturing an optoelectronic device according to claim 9, Characterized in that, The method for manufacturing the optoelectronic device further includes: S3: Form an etching groove on the second semiconductor layer, the groove penetrates through the second semiconductor layer and the active layer, and at least a part of the first semiconductor layer remains below the groove; S4: Form a first electrode at the bottom of the groove; form a second electrode on the second semiconductor layer.

13. The method for manufacturing an optoelectronic device according to claim 9, Characterized in that, The method for manufacturing the optoelectronic device further includes: S3: Peel off the substrate; S4: Form a first electrode below the first semiconductor layer; form a second electrode on the second semiconductor layer.

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