Photoelectric detector and preparation method and application thereof

Abstract

The invention provides a photoelectric detector and a preparation method and application thereof, and belongs to the technical field of photoelectric detectors. The photoelectric detector comprises a substrate; a photosensitive layer on the substrate, the photosensitive layer being adapted to generate photon-generated carriers in response to an optical signal; the phase change layer is made of a vanadium dioxide material, and the phase change layer is located on the photosensitive layer or located between the substrate and the photosensitive layer; the source electrode is located on the photosensitive layer; the drain electrode is located on the phase change layer; wherein in response to an optical signal applied to the photosensitive layer, photon-generated carriers of the photosensitive layer are increased, so that the voltage of the phase change layer is increased, the phase change layer is subjected to phase change, and then the photoelectric detector realizes super-linear response.

Description

Technical Field

[0001] At least one embodiment of the present invention relates to a photodetector, and more particularly to a photodetector capable of achieving superlinear response, and a preparation method and application thereof. Background Art

[0002] Ultraviolet and X-ray detectors, which detect wavelengths below 400 nanometers, are crucial in high-end manufacturing and scientific research. Ultraviolet detectors are commonly used in secure communications and deep space exploration, while X-ray detectors play a vital role in medical research and security inspections. The development of the Internet of Things (IoT) and the resulting increase in data volumes are posing new challenges for the intelligent development of high-energy radiation detectors. This intelligent development involves using detectors as intensity separators to separate noise and apply them to near-sensing architectures, thereby improving the long latency and redundant data inherent in traditional von Neumann architectures. In this context, the development of superlinear detectors not only significantly improves performance but also holds significant significance for the intelligent development of detectors. Summary of the Invention

[0003] In view of this, in order to at least partially solve the above-mentioned technical problems, the present invention provides a photodetector and a preparation method and application thereof to achieve a superlinear response to optical signals.

[0004] According to an embodiment of one aspect of the present invention, there is provided a photodetector, comprising:

[0005] A substrate; a photosensitive layer located on the substrate, the photosensitive layer being suitable for generating photogenerated carriers in response to a light signal; a phase change layer made of vanadium dioxide material, the phase change layer being located on the photosensitive layer, or between the substrate and the photosensitive layer; a source electrode located on the photosensitive layer; and a drain electrode located on the phase change layer; wherein, in response to a light signal applied to the photosensitive layer, the photogenerated carriers of the photosensitive layer increase, resulting in an increase in the voltage of the phase change layer, causing a phase change in the phase change layer, thereby enabling the photodetector to achieve a superlinear response.

[0006] According to another embodiment of the present invention, a method for preparing a photodetector is provided, comprising:

[0007] sequentially growing a photosensitive layer and a phase change layer on a substrate, or sequentially growing a phase change layer and a photosensitive layer on a substrate; and

[0008] A source electrode is grown on the photosensitive layer, and a drain electrode is grown on the phase change layer.

[0009] According to another embodiment of the present invention, a photodetector array formed by a plurality of the above-mentioned photodetectors is provided.

[0010] According to another embodiment of the present invention, there is provided an application of the above-mentioned photodetector array in the field of proximity sensing architecture.

[0011] The photodetector provided by the aforementioned embodiments of the present invention forms a phase change layer on the photosensitive layer or between the substrate and the photosensitive layer. Light signals increase the number of photogenerated carriers in the photosensitive layer, increasing the voltage of the phase change layer, causing it to transition from an insulating phase to a metallic phase. This significantly increases the photoresponse current, enabling the photodetector to achieve a superlinear response. Arrays of photodetectors with superlinear response can be applied to near-field sensing architectures to reduce image noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present invention, but are not intended to limit the present invention.

[0013] Figure 1 A schematic cross-sectional view of a photodetector provided by an embodiment of the present invention;

[0014] Figure 2 A schematic cross-sectional view of a photodetector provided in another embodiment of the present invention;

[0015] Figure 3 A schematic diagram of the working principle of a photoelectric detector provided in an embodiment of the present invention;

[0016] Figure 4 A flow chart of a method for preparing a photodetector provided in an embodiment of the present invention;

[0017] Figure 5 Schematic diagram of the dependence of the photoresponse current of different photodetectors on light intensity;

[0018] Figure 6 The current-voltage characteristic curve of the photodetector provided in Example 1 of the present invention;

[0019] Figure 7 A schematic diagram illustrating the principle of the superlinear response of the photodetector provided in Example 1 of the present invention; and

[0020] Figure 8A to Figure 8C A schematic diagram illustrating the principle of applying a photodetector array provided in an embodiment of the present invention to a near-sensor architecture for image noise reduction processing.

[0021] Description of reference numerals:

[0022] 1-substrate; 2-photosensitive layer; 3-phase change layer; 4-source; 5-drain. DETAILED DESCRIPTION

[0023] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. However, the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to make the present invention thorough and complete and to fully convey the scope of the present invention to those skilled in the art. In the drawings, the dimensions and relative dimensions of layers and regions may be exaggerated for clarity, and like reference numerals denote like elements throughout.

[0024] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the presence of the features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0025] Gallium oxide (Ga2O3) is one of the most widely used materials in the field of high-energy radiation detection. High-energy radiation detectors based on Ga2O3 are not only low-cost and simple to prepare, but also maintain long-term stability in harsh environments such as high temperature, high pressure, and strong radiation. With in-depth research, the performance of Ga2O3 photodetectors has been greatly improved, with improvements in performance indicators such as the light-to-dark current ratio and responsivity. However, achieving superlinear response in a single device has always been a challenge for Ga2O3 photodetectors. The main reason for this is that inherent defects in the growth process of Ga2O3 lead to increased recombination of photogenerated carriers.

[0026] In view of this, the present invention provides a photodetector capable of achieving superlinear response, and a preparation method and application thereof. The photodetector capable of achieving superlinear response is applied to the field of near-sensing architecture, and can be used as an intensity selector to separate background noise and improve image recognition accuracy.

[0027] Figure 1 A schematic cross-sectional view of a photodetector provided in an embodiment of the present invention.

[0028] According to an exemplary embodiment of the present invention, the present invention provides a photodetector, referring to Figure 1 Shown, including:

[0029] Substrate 1;

[0030] a photosensitive layer 2 located on the substrate 1, the photosensitive layer 2 being adapted to generate photogenerated carriers in response to a light signal;

[0031] The phase change layer 3 is made of vanadium dioxide material and is located on the photosensitive layer 2;

[0032] a source electrode 4 located on the photosensitive layer 2; and

[0033] a drain electrode 5 located on the phase change layer 3;

[0034] In response to the light signal applied to the photosensitive layer 2, the photogenerated carriers of the photosensitive layer 2 increase, causing the voltage of the phase change layer 3 to increase, causing the phase change layer 3 to undergo a phase change, thereby enabling the photodetector to achieve superlinear response.

[0035] Figure 2 A schematic cross-sectional view of a photodetector provided in accordance with another embodiment of the present invention.

[0036] refer to Figure 2 As shown, the phase change layer 3 is located between the substrate 1 and the photosensitive layer 2 .

[0037] In some embodiments, the photosensitive layer 2 is made of gallium oxide. The material of the photosensitive layer 2 can be, for example, n-type single crystal gallium oxide, with a doping concentration of 1×10 15 cm -3 ~1×10 19 cm -3 ; The doping concentration can be, for example, 1×10 15 cm -3 , 1×10 16 cm -3 , 1×10 17 cm -3 , 1×10 18 cm -3 , 1×10 19 cm -3 , but not limited to the values listed above. The thickness of the photosensitive layer 2 is between 50 nm and 500 nm, and can be, for example, 50 nm, 100 nm, 200 nm, 300 nm, or 500 nm, but is not limited to the values listed above. If the thickness of the photosensitive layer 2 is too small (e.g., less than 50 nm), the film quality will be poor; if the thickness of the photosensitive layer 2 is too large (e.g., greater than 500 nm), the resistance of the photosensitive layer 2 will increase, resulting in an increase in the operating voltage of the photodetector and increased power consumption of the device. By controlling the thickness of the photosensitive layer 2 within the above range, effective light detection can be achieved.

[0038] In some embodiments, the source electrode 4 forms an ohmic contact with the photosensitive layer 2; the material of the source electrode 4 includes at least one of the following: Ti / Au, Ti / Al / Ni / Au, Cr / Au, Ag, In, Al, Pd, ITO, Ni / Au, Pt, Au, graphene.

[0039] In some embodiments, the source electrode 4 may be in a square, circular, or polygonal shape, for example.

[0040] In some embodiments, the drain electrode 5 forms an ohmic contact with the phase change layer 3; the material of the drain electrode 5 includes at least one of the following: Ti / Au, Ti / Al / Ni / Au, Cr / Au, Ag, In, Al, Pd, ITO, Ni / Au, Pt, Au, and graphene.

[0041] In some embodiments, the drain electrode 5 may be in a square, circular, or polygonal shape, for example.

[0042] Figure 3 A schematic diagram of the working principle of the photoelectric detector provided by an embodiment of the present invention.

[0043] refer to Figure 1 、 Figure 3 As shown, phase change layer 3 is made of vanadium dioxide (VO2). When a light signal irradiates the photosensitive layer 2, it generates photogenerated carriers (electron-hole pairs), causing the conductivity and voltage of the photosensitive layer 2 to change, which in turn causes the voltage of the phase change layer 3 to change. When the voltage of the phase change layer 3 exceeds the threshold voltage Vth (the voltage at which the phase change layer 3 undergoes a phase change), the phase change layer 3 transforms from an insulating phase (insulating VO2) to a metallic phase (metallic VO2). Because the conductivity of the metallic phase is higher than that of the insulating phase, the response current of the photodetector increases significantly after the phase change layer 2 transforms from the insulating phase to the metallic phase.

[0044] In an embodiment of the present invention, the optical signal includes ultraviolet light or X-rays.

[0045] Figure 4 This is a flow chart of a method for preparing a photodetector provided by an embodiment of the present invention.

[0046] According to an exemplary embodiment of the present invention, the present invention provides a method for preparing the above-mentioned photodetector, referring to Figure 4 As shown, it includes: operation S1 to operation S3.

[0047] In operation S1 , a photosensitive layer 2 is grown on a substrate 1 .

[0048] In some embodiments, the photosensitive layer 2 is a gallium oxide single crystal thin film, which is grown by metal organic chemical vapor deposition (MOCVD) or halide vapor phase epitaxy (HVPE).

[0049] In some embodiments, MOCVD is used to grow a gallium oxide single crystal thin film, and the temperature for growing the oxide single crystal thin film is 500°C to 900°C, for example, 500°C, 600°C, 700°C, 800°C, and 900°C, but not limited to the values listed above; if the temperature is too low, the film growth rate is too slow, which is not conducive to film formation; if the temperature is too high, the film formation quality is poor. By controlling the film growth temperature within the above-mentioned required range, a high-quality gallium oxide single crystal thin film can be obtained.

[0050] In some embodiments, the argon flow rate for growing the gallium oxide single crystal film is 500-1000 sccm, and the oxygen flow rate is 300-500 sccm. By controlling the argon flow rate and the oxygen flow rate within the above required range, the film quality of the gallium oxide single crystal film can be improved.

[0051] In operation S2 , a phase change layer 3 is grown on the photosensitive layer 2 .

[0052] In some embodiments, the phase change layer 3 is a vanadium dioxide thin film, which is grown by sputtering or pulsed laser deposition (PLD).

[0053] In some embodiments, a vanadium dioxide film is grown by sputtering, and the temperature for growing the vanadium dioxide film is 400°C to 600°C, for example, 400°C, 500°C, or 600°C, but not limited to the values listed above; by controlling the film growth temperature within the above-mentioned required range, the M phase can be crystallized, so that the vanadium dioxide film has phase change conversion characteristics.

[0054] In some embodiments, the argon flow rate for growing the vanadium dioxide film is 50-100 sccm, and the oxygen flow rate is 1-20 sccm. By controlling the argon flow rate and the oxygen flow rate within the above required range, the film quality of the vanadium dioxide film can be improved.

[0055] In operation S3 , a source electrode 4 is formed on the photosensitive layer 2 , and a drain electrode 5 is formed on the phase change layer 3 .

[0056] The following schematically illustrates the designed photodetector and its preparation method and application. It should be noted that the example is only a specific embodiment of the present invention and does not limit the scope of protection of the present invention.

[0057] Comparative Example 1

[0058] A photodetector is prepared. Specifically, a photosensitive layer is formed on a substrate, and a source electrode and a drain electrode are formed on the photosensitive layer.

[0059] Example 1

[0060] Prepare a photodetector. Specifically, refer to Figure 1As shown, a photosensitive layer 2 is formed on a substrate 1 , a phase change layer 3 is formed on the photosensitive layer 2 , and the phase change layer 3 is made of vanadium dioxide; a source electrode 4 is formed on the photosensitive layer 2 , and a drain electrode 5 is formed on the phase change layer 3 .

[0061] Figure 5 Schematic diagram of the dependence of the photoresponse current of different photodetectors on light intensity.

[0062] The dependence of the photoresponse current of a photodetector on light intensity includes linear response, sublinear response or superlinear response.

[0063] refer to Figure 5 As shown in the field of photodetection, the photoresponse current (also known as photocurrent) of the photodetector I p I follows a power-law dependence on the light intensity P p ∝P α Ideally, the photocurrent of a photodetector is proportional to the light intensity (α = 1), showing a linear response, because one photon can only excite one electron-hole pair.

[0064] refer to Figure 5 As shown, in Comparative Example 1, due to the influence of defects and impurities, it is difficult for the photodetector to achieve a linear response, and the photoresponse current exhibits a sublinear response (α < 1) under high-intensity illumination.

[0065] Superlinear response means that the power exponent α in the power law dependence of the photoresponse current on the light intensity is greater than 1 (I p ∝P α , α>1), that is, with a slight increase in the high-energy irradiation intensity, the photoresponse current shows a rapid increasing trend.

[0066] refer to Figure 5 As shown, the photodetector provided by Example 1 of the present invention achieves superlinear response.

[0067] Figure 6 This is a current-voltage characteristic curve of the photodetector provided in Example 1 of the present invention, wherein the abscissa represents the source-drain voltage Vds and the ordinate represents the current.

[0068] When no light signal (dark) is applied to the photodetector, P1 (200 μm / cm 2 )、P2(400μm / cm 2 )、P3(600μm / cm 2 ) of the optical signal, and obtain the current of the photodetector respectively.

[0069] refer to Figure 6As shown in the figure, after applying a light signal P1 to the photodetector, when the source-drain voltage Vds is V1, the photodetector's photoresponse current increases significantly. This is because at V1, the phase change layer 3 undergoes a phase transition (from an insulating phase to a metallic phase), with V1 being the threshold voltage for the phase transition. When the source-drain voltage Vds is less than V1, the photoresponse current is extremely low because the phase change layer 3 is in the insulating phase. When the source-drain voltage Vds is greater than V1, the phase change layer 3 transitions to the metallic phase. At this point, the photoresponse current is primarily driven by the large number of photogenerated carriers generated in the gallium oxide photosensitive layer, resulting in a significant increase in the photoresponse current.

[0070] When a light signal P2 is applied to the photodetector, the photoresponse current increases significantly when the source-drain voltage Vds reaches V2. This is because at V2, the phase change layer 3 undergoes a phase transition (from insulating to metallic), with V2 being the threshold voltage for this transition. When the source-drain voltage Vds is less than V2, the photoresponse current is extremely low because the phase change layer 3 is in the insulating phase. When the source-drain voltage Vds exceeds V2, the phase change layer 3 transitions to the metallic phase. At this point, the photoresponse current is primarily driven by the large number of photogenerated carriers generated in the gallium oxide photosensitive layer, resulting in a significant increase in the photoresponse current.

[0071] When the P3 light signal is applied to the photodetector, the photoresponse current increases significantly when the source-drain voltage Vds reaches V3. This is because the phase change layer 3 undergoes a phase transition at V3, which is the threshold voltage for the phase transition. When the source-drain voltage Vds is less than V3, the photoresponse current is extremely low because the phase change layer 3 is in an insulating phase. When the source-drain voltage Vds exceeds V3, the phase change layer 3 transitions from an insulating phase to a metallic phase. At this point, the photoresponse current is primarily driven by the large number of photogenerated carriers generated in the gallium oxide photosensitive layer, resulting in a significant increase in the photoresponse current.

[0072] Applying light signals of varying intensities to a photodetector results in different threshold voltages. As the light signal intensity increases (P1 < P2 < P3), the photodetector's threshold voltage (V1 > V2 > V3) decreases. This is because the concentration of photogenerated carriers in the photosensitive layer increases with increasing light signal intensity, leading to an increase in the voltage across the phase change layer, making it more susceptible to phase transitions. This, in turn, causes the photodetector's threshold voltage to decrease. By arbitrarily selecting a voltage between the two threshold voltages as the operating voltage, the photoresponse current can be significantly increased with changes in light intensity, demonstrating that the photodetector achieves a superlinear response to light signals.

[0073] Figure 7 This is a schematic diagram of the superlinear response of the photodetector provided in Example 1 of the present invention.

[0074] refer to Figure 7As shown in the figure, an operating voltage of 15.7V was selected, and light signals P1, P2, and P3 were applied to the photodetector, respectively. When the light signal was adjusted from P1 to P2, the photoresponse current did not change significantly (α = 0.2). However, when the light signal was adjusted from P2 to P3, the photoresponse current changed significantly (α = 4.7), indicating that the photodetector achieved a superlinear response to P3.

[0075] Figure 8A to Figure 8C A schematic diagram illustrating the principle of applying a photodetector array provided in an embodiment of the present invention to a near-sensor architecture for image noise reduction processing.

[0076] The photodetector array provided by the embodiment of the present invention is applied to the near sensor architecture to perform image noise reduction. Figure 8A As shown, the image to be processed is divided into m×n (m≥2, n≥2) array squares, and multiple LEDs are used to illuminate the squares respectively. The different shades of color of each square represent different irradiation light intensities.

[0077] refer to Figure 8B As shown, Figure 8B The color of the squares in the input image to be processed changes from light to dark, indicating that the light intensity changes from small to large. The light signals are P1, P2, and P3, respectively, and P1<P2<P3. Applying the photodetector array to image noise reduction processing, we get the following: Figure 8B As shown in the output diagram, the photoresponse current output by the squares with light signals P1 and P2 does not change much, while the photoresponse current output by the square with light signal P3 increases significantly, allowing the image to separate noise and clearly display the pattern corresponding to the square P3. Figure 8B As shown in the output diagram, image "Y" is displayed, which shows that the photodetector array provided by the embodiment of the present invention can act as an intensity separator to separate background noise.

[0078] refer to Figure 8C As shown, Figure 8C The color of the squares in the input image to be processed changes from light to dark, indicating that the light intensity changes from small to large. The light signals are P1, P2, and P3, respectively, and P1<P2<P3. Applying the photodetector array to image noise reduction processing, we get the following: Figure 8C As shown in the output diagram, the photoresponse current output by the squares with light signals P1 and P2 does not change much, while the photoresponse current output by the square with light signal P3 increases significantly, allowing the image to separate noise and clearly display the pattern corresponding to the square P3. Figure 8C As shown in the output diagram, an image "K" is displayed, which indicates that the photodetector array provided by the embodiment of the present invention can act as an intensity separator to separate background noise.

[0079] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A photoelectric detector, characterized in that: include: substrate (1); A photosensitive layer (2) is located on the substrate (1), and the photosensitive layer (2) is suitable for generating photogenerated carriers in response to a light signal; A phase change layer (3) is made of vanadium dioxide material, and the phase change layer (3) is located on the photosensitive layer (2), or between the substrate (1) and the photosensitive layer (2); A source electrode (4) is located on the photosensitive layer (2); as well as A drain electrode (5) is located on the phase change layer (3); In response to a light signal applied to the photosensitive layer (2), the photogenerated carriers of the photosensitive layer (2) increase, causing the voltage of the phase change layer (3) to increase, causing the phase change layer (3) to undergo a phase change, thereby enabling the photodetector to achieve superlinear response.

2. The photodetector according to claim 1, wherein The photosensitive layer (2) is made of gallium oxide.

3. The photodetector according to claim 1, wherein The phase change of the phase change layer (3) includes: The phase change layer (3) changes from an insulating phase to a metallic phase.

4. The photodetector according to claim 1, wherein The optical signal includes ultraviolet light or X-rays.

5. A method for preparing a photodetector according to any one of claims 1 to 4, characterized in that: include: Growing a photosensitive layer (2) and a phase change layer (3) in sequence on a substrate (1), or growing a phase change layer (3) and a photosensitive layer (2) in sequence on a substrate (1); and A source electrode (4) is grown on the photosensitive layer (2), and a drain electrode (5) is grown on the phase change layer (3).

6. The preparation method according to claim 5, characterized in that The temperature for growing the photosensitive layer (2) is 500° C. to 900° C.; Preferably, the argon flow rate for growing the photosensitive layer (2) is 500-1000 sccm, and the oxygen flow rate is 300-500 sccm.

7. The preparation method according to claim 5, characterized in that The temperature for growing the phase change layer (3) is 400°C to 600°C.

8. The preparation method according to claim 5, characterized in that The argon flow rate for growing the phase change layer (3) is 50-100 sccm, and the oxygen flow rate is 1-20 sccm.

9. A photodetector array formed by a plurality of photodetectors according to any one of claims 1 to 4.

10. Use of the photodetector array according to claim 9 in the field of proximity sensing architecture.

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