Gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots and preparation method thereof

Abstract

This solution provides a gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots and its preparation method, including the following steps: S1: cleaning and drying the substrate on which gallium oxide is grown; S2: etching the surface of gallium oxide to form β ‑Ga2O3 channel; S3: depositing stacked metals on the substrate as electrodes, annealing to alloy the stacked metals to form ohmic contacts with gallium oxide; S4: spin coating p-type NiO quantum dots between the electrodes, introducing p-type NiO quantum dots and n-type through quantum dot integration β ‑Ga2O3 forms a pn heterojunction gallium oxide ultraviolet detector, while improving the photosensitivity and response speed of the gallium oxide solar-blind ultraviolet detector.

Description

Technical Field

[0001] The present invention relates to the field of gallium oxide solar-blind ultraviolet detectors, and in particular to a gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots and a preparation method thereof. Background Art

[0002] Ultraviolet photodetectors are widely used in many fields, including environmental monitoring, space science, flame detection, and national security. The ultraviolet spectrum can be divided into UVA (320-400nm), UVB (280-320nm), and UVC (100-280nm) bands based on wavelength. Among them, the UVC band is an ideal band for high-precision detection due to its weak absorption by the atmosphere.

[0003] Traditional UV photodetectors mostly rely on wide bandgap semiconductor materials, such as Mg x Zn 1-x O、Al x Ga 1-x While materials like N and diamond possess certain photoresponse properties in the ultraviolet band, they generally suffer from slow response speeds and low photoresponsivity. For example, in environmental monitoring scenarios requiring extremely high real-time performance, the slow response speed of traditional detectors may prevent them from capturing rapid changes in UV intensity in a timely manner. When detecting weak UV light, the low photoresponsivity makes it difficult for the detector to accurately detect the signal, affecting data accuracy.

[0004] In recent years, β -Ga2O3 has emerged as a new wide bandgap semiconductor material with a bandgap width of up to 4.9 eV. It exhibits excellent photoresponse performance and stability in the ultraviolet to deep ultraviolet bands, making it a very promising candidate material for UVC photodetectors. Especially in the UVC band, β -Ga2O3 has a high absorption efficiency, can capture ultraviolet light signals more effectively, and has stable performance, making it suitable for ultraviolet detection work with strict precision requirements.

[0005] However, gallium oxide suffers from a low intrinsic carrier mobility (<10 cm² / V·s), which severely limits the transfer efficiency of photogenerated charges and, in turn, hinders improvements in device response speed. Previous gallium oxide UV detectors, despite excellent photoresponse performance in the UV band, have always faced a conflict between responsivity and response speed. To improve photoresponsivity, a common approach is to increase the thickness of the light-absorbing layer or optimize the material's light absorption properties. However, this increases the carrier migration distance, resulting in a decrease in response speed. Furthermore, higher photoresponsivity is prone to carrier recombination, particularly when the carrier migration path is long, significantly increasing the recombination rate and further slowing the response speed.

[0006] In addition, traditional gallium oxide UV detectors mostly use a metal-semiconductor-metal (MSM) structure, which has certain limitations in pursuing high sensitivity and ultrafast response. Although performance can be improved to a certain extent by improving material quality and optimizing device design, the problem of balancing responsiveness and response speed remains difficult to overcome. This bottleneck limits the application of gallium oxide UV detectors in high-performance fields.

[0007] Therefore, there is an urgent need to explore new methods to optimize device performance, achieve the effect of simultaneously improving photoresponsivity and response speed, and effectively suppress the compound effect. Summary of the Invention

[0008] The purpose of the present invention is to provide a gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots and a preparation method thereof, by integrating p-type NiO quantum dots and n-type β -Ga2O3 forms a pn heterojunction gallium oxide ultraviolet detector, while improving the light response and response speed of the gallium oxide solar-blind ultraviolet detector.

[0009] To achieve the above objectives, the present technical solution provides a method for preparing a gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots, comprising the following steps:

[0010] S1: Clean and dry the substrate on which gallium oxide is grown;

[0011] S2: Etching on the surface of gallium oxide β -Ga2O3 channel;

[0012] S3: depositing a stacked metal as an electrode on the substrate, and annealing the stacked metal to alloy the stacked metal to form an ohmic contact with gallium oxide;

[0013] S4: Spin-coating p-type NiO quantum dots between the electrodes.

[0014] In addition, this solution provides a gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots, including:

[0015] substrate;

[0016] Gallium oxide grown on a substrate;

[0017] Electrodes deposited on both sides of the gallium oxide and forming ohmic contact with the gallium oxide, wherein the electrodes are laminated metals;

[0018] P-type NiO quantum dots are spin-coated on the top surface of the gallium oxide and located between the two electrodes.

[0019] Compared with the existing technology, this technical solution has the following characteristics and beneficial effects:

[0020] The gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots provided by the present invention has a simple manufacturing process. β -Ga2O3 forms a type II heterojunction, significantly improving the performance of gallium oxide solar-blind ultraviolet detectors. First, NQDs enhance the absorption of ultraviolet light, especially in the UVC band, improving the photoresponsivity and detectivity of the device while maintaining a relatively fast response speed. By optimizing light absorption and carrier separation, the rise time and fall time of the device are significantly shortened to 0.024 seconds and 0.008 seconds, respectively, greatly improving the response speed. Secondly, the built-in electric field in the type II heterojunction structure effectively promotes the separation and transport of photogenerated carriers, reduces the recombination effect, and thus improves the stability and repeatability of the device. In addition, the surface passivation effect of NQDs reduces defect recombination and further enhances the long-term stability of the device. This design provides a new idea for the development of high-performance ultraviolet photodetectors, solves the contradiction between responsivity and response speed, has broad application prospects, and provides a new idea for the design and optimization of high-performance gallium oxide solar-blind photodetectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of the gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots prepared in this scheme.

[0022] Figure 2 The conventional MSM type gallium oxide UV detector and the nickel oxide quantum dot based gallium oxide solar blind UV detector are placed at 250 nm 1 μW / cm 2 The IV curve was obtained by testing under UV light.

[0023] Figure 3 These are the multi-cycle It curves of a conventional MSM-type gallium oxide UV detector and a nickel oxide quantum dot-based gallium oxide solar-blind UV detector under 250 nm UV light.

[0024] Figure 4 These are the rising and decaying edge diagrams of the It curves of the conventional MSM-type gallium oxide UV detector and the nickel oxide quantum dot-based gallium oxide solar-blind UV detector under 250 nm UV light. DETAILED DESCRIPTION

[0025] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0026] It should be understood by those skilled in the art that, in the disclosure of the present invention, the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0027] Example 1

[0028] This solution provides a method for preparing a gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots, comprising the following steps:

[0029] S1: Clean and dry the substrate on which gallium oxide is grown;

[0030] S2: Etching on the surface of gallium oxide β -Ga2O3 channel;

[0031] S3: depositing a stacked metal as an electrode on the substrate, and annealing the stacked metal to alloy the stacked metal to form an ohmic contact with gallium oxide;

[0032] S4: Spin-coating p-type NiO quantum dots between the electrodes.

[0033] In step S1, the material of the substrate is selected from sapphire, silicon, silicon carbide, and quartz. In a preferred embodiment, the material of the substrate is selected from sapphire.

[0034] like Figure 1 As shown, gallium oxide is grown on a substrate with a gap left from the side of the substrate. In some embodiments, the thickness of the gallium oxide is 424±5 nm, and the thickness of the substrate is 100±5 um.

[0035] In some embodiments, the substrate is ultrasonically cleaned with acetone, isopropyl alcohol, and deionized water for 5 minutes each, followed by drying with a nitrogen gun. Furthermore, the substrate is then rinsed with piranha solution for a period of time after cleaning to remove dangling bonds, surface states, and stubborn contaminants on the substrate surface. The piranha solution used in this solution is a 3:1 mixture of concentrated sulfuric acid and hydrogen peroxide. The piranha solution can be used for 30 minutes.

[0036] In step S2, a channel pattern is formed on the surface of gallium oxide by photolithography and then etched to form β-Ga2O3 channel. Specifically, a layer of photoresist is evenly coated on the surface of gallium oxide, and a mask with a channel pattern is precisely aligned with a substrate coated with the photoresist. Then, light of a specific wavelength is irradiated. The light passes through the pattern on the mask, causing a chemical reaction in the photoresist. The exposed substrate is placed in a developer, and the portion of the photoresist that has undergone chemical changes due to the light is dissolved, thus transferring the channel pattern on the mask to the photoresist, forming a channel pattern in the photoresist layer. Subsequently, the gallium oxide is etched using the photoresist pattern as a mask. During the etching process, the surface portion of the gallium oxide not covered by the photoresist is gradually removed, thereby forming a channel corresponding to the photoresist pattern on the gallium oxide surface.

[0037] In some embodiments, step S2 is performed by inductively coupled plasma etching or reactive ion etching or a combination thereof.

[0038] When inductively coupled plasma etching is used for etching in step S2, the etching gas is one or more of BCl3 and Ar. Preferably, the BCl3 flow rate is 20 sccm, the Ar flow rate is 10 sccm, the etching pressure is 15 mTorr, the RF power is 10 W, the ICP power is 80 W, and the etching time is 30 s.

[0039] In some embodiments, the length of the channel formed by etching in step S2 is 180±5 um and the width is 30±5 um. Preferably, the length of the channel formed by etching in step S2 is 180 um and the width is 30 um.

[0040] In some embodiments, the thickness of the channel formed by etching in step S2 is 420±5 nm. Preferably, the thickness of the channel formed by etching in step S2 is 420 nm.

[0041] In step S3 , an electrode pattern is formed by photolithography, a stacked metal is deposited on the substrate as an electrode, and annealing is performed to alloy the stacked metal to form an ohmic contact with gallium oxide.

[0042] In some embodiments, electron beam evaporation, thermal evaporation or magnetron sputtering is used to deposit a stacked metal on a substrate as an electrode. Preferably, magnetron sputtering is used to deposit a stacked metal on a substrate as an electrode.

[0043] In some embodiments, the electrode patterns are formed using standard UV photolithography.

[0044] In some embodiments, the material of the laminated metal is selected from one of Ti / Au and Ti / Al / Ni / Au. In a preferred embodiment, the material of the laminated metal is selected from Ti / Au laminated metal.

[0045] like Figure 1As shown, this solution deposits stacked metals on both sides of the gallium oxide, and the bottom of the stacked metal on each side of the gallium oxide covers the top surface of the substrate, and the top covers both ends of the top surface of the gallium oxide and contacts the side surface of the gallium oxide.

[0046] In some embodiments, the stacked metal covers 20 um on both ends of the top surface of the gallium oxide.

[0047] In some embodiments, the stacked metals deposited on both sides of the gallium oxide are symmetrically arranged relative to the gallium oxide.

[0048] In addition, this solution uses a rapid thermal annealing device (RTP) or a tubular annealing furnace to anneal the deposited metal stack, thereby alloying the metal stack to form an ohmic contact with gallium oxide. Preferably, when using the rapid thermal annealing device (RTP) to anneal the deposited metal stack, the annealing is performed in a nitrogen atmosphere at an annealing temperature of 470°C for 1 minute.

[0049] After annealing, this solution forms a lateral MSM structure. This structure uses gallium oxide as the semiconductor layer and metal electrodes on either side. When the detector is exposed to solar-blinding ultraviolet light, the gallium oxide absorbs photon energy. If the photon energy exceeds the semiconductor's bandgap, electron-hole pairs are generated. These electron-hole pairs are photogenerated carriers. Applying a bias voltage across the metal electrodes creates a transverse electric field within the semiconductor layer. This transverse electric field causes the photogenerated electrons and holes to migrate toward the positive and negative electrodes, respectively, where they are collected by the electrodes, generating a photocurrent. By measuring the magnitude of this photocurrent, the UV light signal can be detected.

[0050] In step S4, a p-type NiO solution is spin-coated between the electrodes on the top surface of the gallium oxide to form p-type NiO quantum dots.

[0051] In some embodiments, the NiO quantum dot area pattern is required on the Ga2O3 film by photolithography, and it is placed in the middle of the glue machine suction cup, the vacuum pump is turned on to evacuate, and the film is adsorbed and fixed on the suction cup. 15 μL of the precursor solution is extracted with a pipette and drop-coated on the surface of the film. The spin coating is divided into two parts. The first part rotates at a speed of 550 rpm for 15 seconds, and the second part rotates at a speed of 2500 rpm for 45 seconds. Two different speeds of rotation can obtain a more uniform film. After spin coating, it is placed on the annealing table of the fume hood for annealing at an annealing temperature of 100 ° C for 20 minutes, and the peeling is completed in acetone to obtain the photolithographic NiO quantum dot area.

[0052] In some embodiments, the concentration of the p-type NiO solution is 20 g / L.

[0053] In some embodiments, the density of quantum dots is 3.67×10 17 / square centimeter, and the thickness is 24 nm.

[0054] This scheme introduces p-type NiO quantum dots and n-type β -Ga2O3 forms a pn heterojunction gallium oxide ultraviolet detector. Among them, NiO quantum dots can effectively enhance the absorption of ultraviolet light due to their smaller size and higher specific surface area, especially in the deep ultraviolet (UVC) band. Compared with NiO thin films, quantum dots can more efficiently capture and absorb ultraviolet light, thereby improving the responsiveness of the photodetector, so that the device can still maintain high sensitivity under low light conditions. The introduction of quantum dots can effectively improve the carrier separation efficiency, especially when forming a heterojunction.

[0055] And the NiO quantum dots of this scheme are β In the type II heterojunction structure formed by -Ga2O3, the size effect of quantum dots can accelerate the separation and transport of photogenerated carriers, thereby significantly shortening the rise time and fall time (rise time 0.024 seconds, fall time 0.008 seconds) and improving the response speed. This solves the problem of slow carrier migration speed in traditional nickel oxide films, making the photodetector perform well in fast-response applications and successfully solving the trade-off between light response and response speed in traditional structures.

[0056] Furthermore, nickel oxide quantum dots have many surface states, but due to their high specific surface area and size effect, surface passivation can effectively reduce surface defects and recombination effects. Compared with nickel oxide thin films, quantum dots have fewer surface defects, and through surface passivation of quantum dots, the stability and repeatability of the device are significantly improved. This allows quantum dots to improve the stability of photodetectors while also reducing performance degradation during long-term operation.

[0057] In summary, this method successfully overcomes the shortcomings of traditional gallium oxide detectors by optimizing light absorption and carrier transport, achieving a dual improvement in responsivity and response speed. Furthermore, compared to the method of depositing NiO thin films, the spin-coated NiO quantum dot method offers a simpler process and lower costs.

[0058] Example 2

[0059] like Figure 1 As shown, this solution provides a gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots, which is prepared according to the above method, including:

[0060] substrate;

[0061] Gallium oxide grown on a substrate;

[0062] Electrodes deposited on both sides of the gallium oxide and forming ohmic contact with the gallium oxide, wherein the electrodes are laminated metals;

[0063] P-type NiO quantum dots are spin-coated on the top surface of the gallium oxide and located between the two electrodes.

[0064] The contents of the second embodiment that are the same as those of the first embodiment will not be described again in detail.

[0065] Example 3

[0066] In order to verify the performance optimization of the gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots in this scheme compared with the conventional MSM type gallium oxide ultraviolet detector, the following embodiment is designed

[0067] Gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots in this scheme:

[0068] Step (1): Gallium oxide grown on sapphire material was ultrasonically cleaned with acetone, isopropanol and deionized water for 5 minutes respectively, and then cleaned with piranha solution (concentrated H2SO4:H2O2=3:1) for 30 minutes after organic cleaning, and then dried with a nitrogen gun; Step (2): Photolithography was used to form a channel pattern, and the channel was etched on the substrate using the ICP method, wherein the BCl3 flow rate was 20 sccm, the Ar flow rate was 10 sccm, the etching pressure was 15 mTorr, the RF power was 10 W, the ICP power was 80 W, and the etching time was 30 s; Step (3): Photolithography was used to form an electrode pattern, and Ti / Au stacked metal was deposited using magnetron sputtering technology, and the electrode was formed by peeling; Step (4): The ohmic contact was formed using the RTP method, and annealing was carried out in a nitrogen atmosphere at a temperature of 470 °C for 1 min annealing; Step (5): Photolithographically define the pattern of the NiO quantum dot area on the Ga2O3 film, place it in the middle of the coating machine suction cup, turn on the vacuum pump to evacuate, and the film is adsorbed and fixed on the suction cup. Use a pipette to extract 15 μL of the precursor solution and drop it on the surface of the film. The spin coating is divided into two parts. The first part rotates at a speed of 550 rpm for 15 seconds, and the second part rotates at a speed of 2500 rpm for 45 seconds. Two different speeds of rotation can obtain a more uniform film. After spin coating, place it on the annealing table in the fume hood for annealing at a temperature of 100°C for 20 minutes, and complete the peeling in acetone to obtain the photolithographic NiO quantum dot area.

[0069] Conventional MSM gallium oxide UV detector:

[0070] Step (1): Gallium oxide grown on sapphire material was ultrasonically cleaned with acetone, isopropanol and deionized water for 5 minutes respectively, and then cleaned with piranha solution (concentrated H2SO4:H2O2=3:1) for 30 minutes after organic cleaning, and then blown dry with a nitrogen gun after cleaning; Step (2): A channel pattern was formed by photolithography, and a channel was etched on the substrate by ICP method, wherein the BCl3 flow rate was 20 sccm, the Ar flow rate was 10 sccm, the etching pressure was 15 mTorr, the RF power was 10 W, the ICP power was 80 W, and the etching time was 30 s; Step (3): An electrode pattern was formed by photolithography, and Ti / Au stacked metal was deposited by magnetron sputtering technology, and the electrode was formed by peeling; Step (4): Ohmic contact was formed by RTP method, and annealing was performed in a nitrogen atmosphere at an annealing temperature of 470 °C for 1 minute.

[0071] The conventional MSM-type gallium oxide UV detector and the nickel oxide quantum dot-based gallium oxide solar-blind UV detector of the present invention were placed at 250 nm 1 μW / cm 2 The IV curve obtained by testing under UV light is as follows Figure 2 As shown in the figure, the It curve under 250 nm ultraviolet light is as follows Figure 3 As shown in Figure 2, the rising and decaying edges of the It curve under 250 nm UV light are as follows: Figure 4 As shown, it can be seen that the gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots in this scheme solves the contradiction between responsivity and response speed.

[0072] Those skilled in the art should understand that the technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0073] The above embodiments merely illustrate several embodiments of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A method for preparing a gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots, characterized in that: The following steps are involved: S1: Clean and dry the substrate on which gallium oxide is grown; S2: Etching on the surface of gallium oxide β -Ga2O3 channel, β -Ga2O3 channels are spaced laterally in the gallium oxide layer and communicate with the substrate; S3: depositing a stacked metal as an electrode on the substrate, and annealing the stacked metal to alloy the stacked metal to form an ohmic contact with gallium oxide; S4: Spin-coating p-type NiO quantum dots between the electrodes.

2. The method for preparing a gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots according to claim 1, characterized in that: Gallium oxide grows on a substrate with a gap between the sides of the substrate. The thickness of the gallium oxide film is 424±5 nm, and the thickness of the substrate is 100±5 um.

3. The method for preparing a gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots according to claim 1, characterized in that: The length of the trench formed by etching in step S2 is 180±5 um and the width is 30±5 um.

4. The method for preparing a gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots according to claim 1, characterized in that: A stacked metal is deposited on both sides of the gallium oxide, wherein the bottom of the stacked metal on each side of the gallium oxide covers the top surface of the substrate, the top covers the top surface of the gallium oxide, and contacts the side surface of the gallium oxide.

5. The method for preparing a gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots according to claim 1, characterized in that: After annealing, a lateral MSM structure is formed, wherein the lateral MSM structure uses gallium oxide as a semiconductor layer and electrodes on both sides are metal electrodes.

6. The method for preparing a gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots according to claim 1, characterized in that: The spin coating was divided into two parts, the first part was a spin speed of 550 rpm for 15 seconds, and the second part was a spin speed of 2500 rpm for 45 seconds.

7. The method for preparing a gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots according to claim 1, characterized in that: The concentration of the p-type NiO solution was 20 g / L.

8. The method for preparing a gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots according to claim 1, characterized in that: The density of quantum dots is 3.67×10 17 / square centimeter, and the thickness is 24 nm.

9. A gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots, characterized in that: The method for preparing a gallium oxide solar-blind ultraviolet detector based on nickel oxide quantum dots according to any one of claims 1 to 8 comprises: substrate; Gallium oxide grown on a substrate; Electrodes deposited on both sides of the gallium oxide and forming ohmic contact with the gallium oxide, wherein the electrodes are laminated metals; P-type NiO quantum dots are spin-coated on the top surface of the gallium oxide and located between the two electrodes.

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