A device structure for improving the quantum efficiency of SiC photoconductive devices

Abstract

The present invention relates to the field of optical waveguide devices, in particular to a device structure for improving the quantum efficiency of SiC optical waveguide devices, including a SiC substrate, transparent electrodes are provided on the upper and lower surfaces of the SiC substrate, and DBR reflection layers are provided on the outer surfaces of the two transparent electrodes; the DBR reflection layer includes a plurality of high refractive index layers and a plurality of low refractive index layers, the plurality of high refractive index layers and the plurality of low refractive index layers are arranged alternately, and the uppermost layer and the lowermost layer of the DBR reflection layer are high refractive index layers. The present invention can enhance the response ability of the optical waveguide device to external light excitation.

Description

Technical Field

[0001] The present invention relates to the field of optical waveguide devices, and particularly to a device structure for improving the quantum efficiency of SiC optical waveguide devices. Background Art

[0002] The application of optical waveguide devices in fields such as high-power fields and ultrafast electron technology has attracted great interest, and the future prospects are promising. Silicon carbide (SiC) has become a promising material for optical waveguide devices due to its high critical electric field, high electron saturation velocity, high thermal conductivity, and thermal stability. However, the biggest difficulty currently hindering the practical application of SiC optical waveguide devices is their extremely low quantum efficiency, which requires a large laser power to excite sufficient carriers and sufficient output in the optical waveguide device. High-power lasers require additional volume and larger supporting power supply facilities, making the application system of the optical waveguide device too complex and expensive. Therefore, effectively improving the quantum efficiency of the optical waveguide device through appropriate processes or packaging structures can significantly reduce the requirements for the corresponding light source and supporting system, which is beneficial to promoting the practical application of the optical waveguide device.

[0003] The quantum efficiency of an optical waveguide device is mainly divided into two parts: light absorption rate and photoexcitation rate. The light absorption rate determines the effective absorption ability of the device to external laser energy, while the photoexcitation rate determines the effective activation ability of the absorbed light energy to the internal carriers of the device. By designing the device structure to enhance the optical path of the incident light inside the optical waveguide device, it is an effective way to improve the light absorption rate of the optical waveguide device. Summary of the Invention

[0004] The purpose of the present invention is to provide a device structure for improving the quantum efficiency of SiC optical waveguide devices to solve the above problems and achieve the purpose of enhancing the response ability of the optical waveguide device to external optical excitation.

[0005] To achieve the above purpose, the present invention provides the following solution:

[0006] A device structure for improving the quantum efficiency of SiC optical waveguide devices includes a SiC substrate, transparent electrodes are provided on the upper and lower surfaces of the SiC substrate, and DBR reflection layers are provided on the outer surfaces of the two transparent electrodes;

[0007] The DBR reflection layer includes a plurality of high refractive index layers and a plurality of low refractive index layers, the plurality of high refractive index layers and the plurality of low refractive index layers are arranged alternately, and the uppermost layer and the lowermost layer of the DBR reflection layer are high refractive index layers.

[0008] Preferably, the SiC substrate is a 4H-SiC material doped with vanadium, the doping concentration of vanadium is 10^ 16 ~10^ 17 cm -3 , and the thickness of the SiC substrate is 800 - 1500 μm.

[0009] Preferably, the transparent electrode is made of aluminum-doped zinc oxide material or gallium-doped zinc oxide material. The transparent electrode is deposited on the upper and lower surfaces of the SiC substrate by magnetron sputtering at a high temperature. The thickness of the transparent electrode is 300 - 700 nm, and the growth temperature of the transparent electrode is 350 - 500 °C.

[0010] Preferably, the high refractive index layer is one of titanium dioxide, aluminum oxide, and aluminum nitride, and the thickness of the high refractive index layer is 30 - 80 nm.

[0011] Preferably, the low refractive index layer is one of silicon dioxide and silicon nitride, and the thickness of the low refractive index layer is 80 - 150 nm.

[0012] Preferably, the total number of the plurality of high refractive index layers and the plurality of low refractive index layers is 10 - 30 layers, and the total thickness of the plurality of high refractive index layers and the plurality of low refractive index layers is 0.5 - 3.6 μm.

[0013] The present invention has the following technical effects:

[0014] By changing the structure of the SiC optical waveguide device, the present invention enables the laterally incident laser to enter the SiC substrate and be reflected multiple times between the upper and lower DBR reflection layers, thereby increasing the effective light absorption ratio of the optical waveguide device and enhancing the response ability of the optical waveguide device to external light excitation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0016] Figure 1 It is a schematic diagram of the structure of the optical waveguide device of the present invention;

[0017] Figure 2 It is a schematic diagram of the structure of the DBR reflection layer of the present invention;

[0018] Figure 3 It is a diagram showing the influence of the number of DBR reflection layers of the present invention on the reflectivity;

[0019] Figure 4 It is the reflection effect diagram of the incident light of the present invention.

[0020] Among them, 1 is the SiC substrate; 2 is the transparent electrode; 3 is the DBR reflection layer; 4 is the high refractive index layer; 5 is the low refractive index layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Referring to Figures 1-4 As shown, the present invention provides a device structure for improving the quantum efficiency of a SiC photoconductive device, including a SiC substrate 1, transparent electrodes 2 are provided on the upper and lower surfaces of the SiC substrate 1, and DBR reflection layers 3 are provided on the outer surfaces of the two transparent electrodes 2;

[0024] The DBR reflection layer 3 includes a plurality of high-refractive-index layers 4 and a plurality of low-refractive-index layers 5, the plurality of high-refractive-index layers 4 and the plurality of low-refractive-index layers 5 are arranged alternately, and the uppermost and lowermost layers of the DBR reflection layer 3 are high-refractive-index layers 4.

[0025] In the present invention, by providing two DBR reflection layers 3 on both sides of the SiC substrate 1, the SiC substrate 1 absorbs the effective light, and the light that is not completely absorbed is incident on the DBR reflection layer 3, and then is reflected back into the SiC substrate 1 by the DBR reflection layer 3 for continued absorption. This process is repeated, enhancing the light absorption efficiency of the SiC substrate 1. The DBR reflection layer 3 is set as a stack of high-refractive-index layers 4 and low-refractive-index layers 5, changing the reflection angle of light in the DBR reflection layer 3, thereby enhancing the number of times light travels between the two DBR reflection layers 3, and thus increasing the light absorption efficiency of the SiC substrate 1.

[0026] In a further optimized solution, the SiC substrate 1 is a 4H-SiC material doped with vanadium, and the doping concentration of vanadium is 10^ 16 ~10^ 17 cm -3 , and the thickness of the SiC substrate 1 is 800 - 1500 μm. The activation light range of the SiC substrate 1 is improved by doping vanadium guest atoms into the SiC substrate 1.

[0027] In a further optimized solution, the transparent electrode 2 is an aluminum-doped zinc oxide material or a gallium-doped zinc oxide material. The transparent electrode 2 is deposited on the upper and lower surfaces of the SiC substrate 1 by magnetron sputtering at a high temperature. The thickness of the transparent electrode 2 is 300 - 700 nm, and the growth temperature of the transparent electrode 2 is 350 - 500 °C. The thickness of the transparent electrode 2 is an odd multiple of one-fourth of the incident light wavelength.

[0028] For a further optimized solution, the high refractive index layer 4 is one of titanium dioxide, aluminum oxide, and aluminum nitride, and the thickness of the high refractive index layer 4 is 30 - 80 nm. The high refractive index layer 4 is deposited on the surfaces of the upper and lower lens electrodes at a high temperature by methods such as magnetron sputtering and ion-assisted physical vapor deposition, and the growth temperature is 350 - 500 °C;

[0029] For a further optimized solution, the low refractive index layer 5 is one of silicon dioxide and silicon nitride, and the thickness of the low refractive index layer 5 is 80 - 150 nm. The low refractive index layer 5 is deposited on the surfaces of the upper and lower lens electrodes at a high temperature by methods such as magnetron sputtering and ion-assisted physical vapor deposition, and the growth temperature is 350 - 500 °C;

[0030] For a further optimized solution, the total number of several high refractive index layers 4 and several low refractive index layers 5 is 10 - 30 layers, and the total thickness of several high refractive index layers 4 and several low refractive index layers 5 is 0.5 - 3.6 μm. The high refractive index layer 4 and the low refractive index layer 5 are each a quarter of the incident wavelength.

[0031] After the structural improvement of the present invention, the reflectivity for the incident light wavelength exceeds 98%.

[0032] The high refractive index layer 4 is set to 6 layers, and the low refractive index layer 5 is set to 5 layers, for a total of 11 layers with a total thickness of 532 nm.

[0033] On the surface of the SiC substrate 1, a transparent electrode 2 is formed by high-temperature sputtering of an AZO thin film using the magnetron sputtering method. Then, the same process operation is performed on the back surface of the SiC substrate 1, and an AZO thin film of the same thickness is also sputtered to form a transparent electrode 2. The thickness of the thin film satisfies an odd multiple of 1 / 4 of the incident wavelength, i.e., 1 / 4, 3 / 4, 5 / 4, etc. At this thickness, the loss of light energy in the AZO material can be minimized.

[0034] On the surface of the sputtered AZO thin film, titanium dioxide of the high refractive index layer 4 is continuously sputtered at a high temperature using the magnetron sputtering method, and the thickness satisfies 1 / 4 of the incident light wavelength. After sputtering is completed, silicon dioxide of the low refractive index layer 5 is continuously sputtered, and the thickness also satisfies 1 / 4 of the incident light wavelength. Alternate sputtering is performed for a total of more than 11 layers, ensuring that the first layer and the last layer are both the high refractive index layer 4. The device is flipped, and the DBR structure is prepared on the back surface using the same process. In this way, the structure preparation of the optical waveguide device is completed.

[0035] Regarding the influence of the complete device structure on the reflection effect of the incident light, when the reflection test of the light incident from the side is sufficient, more than 90% of the incident light energy can be absorbed by the SiC substrate 1.

[0036] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0037] The embodiments described above are only for describing the preferred mode of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solution of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A device structure for improving the quantum efficiency of a SiC photoconductive device, characterized in that: It includes a SiC substrate (1), transparent electrodes (2) are provided on the upper and lower surfaces of the SiC substrate (1), and a DBR reflection layer (3) is provided on the outer surfaces of the two transparent electrodes (2); The DBR reflection layer (3) includes a plurality of high refractive index layers (4) and a plurality of low refractive index layers (5), the plurality of high refractive index layers (4) and the plurality of low refractive index layers (5) are arranged alternately, and the uppermost layer and the lowermost layer of the DBR reflection layer (3) are high refractive index layers (4); The DBR reflection layer (3) is set as the superposition of the high refractive index layer (4) and the low refractive index layer 5 (5), the reflection angle of light in the DBR reflection layer (3) is changed, so that the number of times of light in the two DBR reflection layers (3) is enhanced, thereby increasing the light absorption efficiency of the SiC substrate (1); The laterally incident laser enters the SiC substrate (1); The thickness of the transparent electrode (2) satisfies an odd multiple of 1 / 4 of the incident wavelength.

2. The device structure for improving the quantum efficiency of a SiC photoconductive device according to claim 1, wherein: The SiC substrate (1) is a vanadium-doped 4H-SiC material, and the doping concentration of vanadium is 10^ 16 ~10^ 17 cm -3 , and the thickness of the SiC substrate (1) is 800 - 1500 μm.

3. A device structure for improving the quantum efficiency of a SiC optical waveguide device according to claim 1, characterized in that: The transparent electrode (2) is a zinc oxide material doped with aluminum or a zinc oxide material doped with gallium. The transparent electrode (2) is deposited on the upper and lower surfaces of the SiC substrate (1) by magnetron sputtering at high temperature. The thickness of the transparent electrode (2) is 300-700 nm, and the growth temperature of the transparent electrode (2) is 350-500 °C.

4. A device structure for improving the quantum efficiency of a SiC photoconductive device according to claim 1, characterized in that: The high refractive index layer (4) is one of titanium dioxide, aluminum oxide, and aluminum nitride, and the thickness of the high refractive index layer (4) is 30-80 nm.

5. The device structure for improving the quantum efficiency of a SiC photoconductive device according to claim 1, characterized in that: The low refractive index layer (5) is one of silicon dioxide and silicon nitride, and the thickness of the low refractive index layer (5) is 80-150 nm.

6. A device structure for improving the quantum efficiency of a SiC photoconductive device according to claim 1, characterized in that: The total number of the plurality of high refractive index layers (4) and the plurality of low refractive index layers (5) is 11-31 layers, and the total thickness of the plurality of high refractive index layers (4) and the plurality of low refractive index layers (5) is 0.5-3.6 μm.

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