Gallium oxide-based ultraviolet detector with vertical structure and preparation method of gallium oxide-based ultraviolet detector

Abstract

The invention relates to the technical field of semiconductor photoelectric detectors, in particular to a gallium oxide-based ultraviolet detector with a vertical structure and a preparation method of the gallium oxide-based ultraviolet detector. The detector comprises a bottom electrode, a substrate, a buffer layer, an epsilon-phase gallium oxide layer and a top electrode which are arranged from bottom to top, the buffer layer is nickel oxide; the substrate is a silicon substrate; the top electrode and the bottom electrode are used for applying bias voltage to realize polarization deflection of the epsilon-phase gallium oxide layer; the buffer layer is nickel oxide (111), and the thickness of the buffer layer is 1-50 nm. The method has the advantages that technical means such as doping, surface treatment or high-temperature annealing do not need to be introduced into the epsilon-phase gallium oxide thin film; positive and negative bias voltages are applied to the ferroelectric thin film material, and the electric dipoles are arranged along the direction of an electric field, so that the current regulation of a depolarization field on the device is realized, and the performance of the detector is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor photoelectric detectors, and in particular to a gallium oxide-based vertical structure ultraviolet detector and a preparation method thereof. Background Art

[0002] Solar-blind ultraviolet photodetectors have attracted extensive attention from researchers in recent years because of their important application prospects in military and civilian fields. Solar-blind ultraviolet photodetectors based on wide-bandgap semiconductor materials have become a new generation of ultraviolet detection devices. Gallium oxide, one of the wide-bandgap semiconductor materials, has α Mutually, β Mutually, c Mutually, d Mutually, e Mutually, k There are 6 different crystal phase structures, among which e The crystal structure of phase gallium oxide belongs to the orthorhombic system. Compared with the monoclinic system β Phase gallium oxide, e Phase gallium oxide has a higher symmetry, that is, non-inversion symmetry along the c-axis, thus showing certain ferroelectric polarization characteristics (residual polarization intensity is 5~6 μC / cm), making e Phase gallium oxide materials can be used as both the ferroelectric layer and the photosensitive layer of solar-blind photodetectors. e Due to its metastable state, high-quality pure gallium oxide thin films can be obtained. e The phase of gallium oxide thin film is very difficult, which seriously affects e Secondly, the performance of existing gallium oxide-based solar-blind ultraviolet detection devices. e Most of the solar-blind ultraviolet detectors based on gallium oxide have traditional planar electrode structures, and their planar electric fields are difficult to e Phase GaO2 thin film polarization reversal, which also seriously limits the use of e The development of the performance of solar-blind detectors controlled by the ferroelectric properties of phase-phase gallium oxide materials. According to previous literature, theoretically e The photocurrent gain of the Schottky barrier prepared on the phase gallium oxide film comes from the charging and discharging process of the deep energy level defects in the depletion region of the Schottky barrier, which makes the induced current in the local area of ​​the film increase with the increase of the external bias voltage. By applying positive and negative bias voltages to the ferroelectric thin film material, the electric dipoles will be arranged along the direction of the electric field. When the depolarization field is the same as the built-in electric field of the heterojunction, the photocurrent of the device is enhanced; when the depolarization field is opposite to the built-in electric field of the heterojunction, the photocurrent of the device is weakened, realizing the current regulation of the device by the depolarization field, thereby effectively improving the performance of the detector.

[0003] at present, ePhase gallium oxide has been successfully grown on many different substrates. It has been reported that gallium chloride and oxygen were used as precursors and halide vapor phase epitaxy was used at 550 ° C to grow gallium nitride (0001), aluminum nitride (0001), β Phase-pure gallium oxide (-201) substrates were first realized e Epitaxial growth of gallium oxide thin films, but e There are tiny misorientation domains in the phase gallium oxide. Another study found that growing a cubic nickel oxide layer as a buffer layer on a sapphire substrate and then epitaxially growing e The use of a pure phase gallium oxide film to suppress the nickel oxide buffer layer can prevent the formation of other crystal forms, thereby retaining the pure phase e phase gallium oxide thin film, but e The quality of the phase-phase gallium oxide film still needs to be improved. In the same year, epitaxial growth of gallium oxide on tin dioxide / sapphire substrate was also reported. e phase gallium oxide film, and observed complete e Ferroelectric hysteresis curve of phase GaO thin film. Other studies have found that the e The crystal quality and uniformity of the phase gallium oxide film are poor. After inserting the aluminum nitride layer, e All these results show that e Phase gallium oxide thin films can be grown by various mature deposition methods and have the potential to be used in further device applications. In addition, some literature studies have achieved this by doping with tin, magnesium, and zinc elements. e Another study used pulsed laser deposition (PLD) technology to deposit single crystals on a c-plane sapphire substrate. e phase gallium oxide, and found that Sn-doped e The bandgap of the phase GaO2 film increases with the increase of Sn content, but too many Sn atoms enter the lattice to replace the deep-level Ga 3+ , and did not increase the conductivity of the device, thus limiting the device performance. It has been reported that magnesium-doped e The solar-blind photodetector with a metal-semiconductor-metal (MSM) structure of a phase-conductor GaO thin film can operate stably and has stable optical switching characteristics under different applied voltages and light intensities. e Phase GaO / Undoped e Phase GaO and Au / Mg doped e The large number of defects at the interface of gallium oxide phases limits the performance of some detectors. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a gallium oxide-based vertical structure ultraviolet detector and a preparation method thereof.

[0005] The first object of the present invention is to provide a gallium oxide-based vertical structure ultraviolet detector, comprising a bottom electrode, a substrate, a buffer layer, e phase gallium oxide layer and top electrode; The buffer layer is nickel oxide; the substrate is a silicon substrate; The top electrode and the bottom electrode are used to apply a bias voltage to achieve e Polarization deflection of the phase gallium oxide layer.

[0006] Preferably, the buffer layer is nickel oxide (111), and the thickness of the buffer layer is 1-50 nm.

[0007] Preferably, e The thickness of the phase gallium oxide layer is 0.1-10 μm; and the substrate is a silicon (111) substrate.

[0008] Preferably, the top electrode is a point electrode, and the material of the point electrode has a conductivity higher than 5×10 6 S / M, electrode material with strong adhesion.

[0009] Preferably, the diameter of the point electrode is 10 μm.

[0010] Preferably, the electrode thickness of the bottom electrode and the top electrode is 10-200 nm; the material of the top electrode is nickel, gold, titanium, platinum or conductive silver paste; the material of the bottom electrode is conductive silver paste.

[0011] The second object of the present invention is to provide a method for preparing a gallium oxide-based vertical structure ultraviolet detector, which specifically comprises the following steps: S1. Cleaning the substrate, and placing the substrate in a growth chamber of magnetron sputtering after cleaning; S2. growing a buffer layer on the substrate by magnetron sputtering; S3. After the buffer layer is taken out, it is placed in the MOCVD reaction chamber for e Growth of phase gallium oxide layers; S4. Applying a photoresist on the ε-phase gallium oxide layer, and forming a metal electrode pattern on the photoresist after pre-baking, exposure, post-baking, and development; S5. Depositing metal on the metal electrode pattern region by electron beam deposition; performing a lift-off process to obtain a top electrode after peeling; S6. The electrode material is uniformly coated on the surface of the substrate facing away from the buffer layer, and the bottom electrode is obtained after hot plate baking, thereby completing the preparation of the gallium oxide-based vertical structure ultraviolet detector.

[0012] Preferably, in step S3 e The growth temperature of the phase gallium oxide layer is 600~700°C, the growth time is 100~150 minutes, and the growth pressure is 750~850Pa.

[0013] Preferably, in step S2, the RF power of magnetron sputtering is 130-180 W, the gas pressure during sputtering is 0.3-1 Pa, the oxygen flow rate is 10-15 sccm, the argon flow rate is 5-10 sccm, and the growth time is 10-30 minutes.

[0014] Preferably, the deposition temperature in step S4 is room temperature, the metal target is platinum, the pre-sputtering time is 1 to 5 minutes, and the deposition time is 15 to 25 minutes.

[0015] Compared with the prior art, the present invention can achieve the following beneficial effects: The present invention proposes a method for epitaxially growing high-quality e A vertical solar-blind ultraviolet detector was constructed by using a gallium oxide thin film e The advantages of the gallium oxide-based vertical structure ultraviolet detector preparation method provided by the present invention are that on the one hand, no e On the other hand, by introducing technical means such as doping, surface treatment or high-temperature annealing into the phase gallium oxide film; on the other hand, by applying positive and negative bias voltages to the ferroelectric thin film material, the electric dipoles will be arranged along the direction of the electric field. When the depolarization field is the same as the built-in electric field of the heterojunction, the photocurrent of the device is enhanced; when the depolarization field is opposite to the built-in electric field of the heterojunction, the photocurrent of the device is weakened, thereby realizing the current regulation of the device by the depolarization field, thereby effectively improving the performance of the detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the overall structure of a gallium oxide-based vertical structure ultraviolet detector provided according to an embodiment of the present invention.

[0017] Figure 2 Schematic diagram of a cross-section of a gallium oxide-based vertical structure ultraviolet detector provided according to an embodiment of the present invention.

[0018] Figure 3 It is a flow chart of preparing a gallium oxide-based vertical structure ultraviolet detector provided according to an embodiment of the present invention.

[0019] Figure 4 The invention relates to a gallium oxide-based vertical structure ultraviolet detector. e XRD pattern of the phase gallium oxide layer.

[0020] Figure 5 The invention relates to a gallium oxide-based vertical structure ultraviolet detector. e SEM image of the phase gallium oxide layer.

[0021] Reference numerals: 101. Substrate; 102. Buffer layer; 103. e Phase gallium oxide layer; 104. Point electrode; 105. Bottom electrode. DETAILED DESCRIPTION

[0022] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same modules are represented by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, the detailed description thereof will not be repeated.

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0024] The present invention provides a gallium oxide-based vertical structure ultraviolet detector, comprising a bottom electrode, a substrate, a buffer layer, e phase gallium oxide layer and top electrode; The buffer layer is nickel oxide; the substrate is a silicon substrate; The top electrode and the bottom electrode are used to apply a bias voltage to achieve e Polarization deflection of phase gallium oxide layer; The top electrode is a point electrode, and the material of the point electrode has a conductivity higher than 5×10 6 S / M, electrode material with strong adhesion, preferably nickel, gold, titanium, platinum or conductive silver paste; in a specific embodiment, the material is platinum; The diameter of the point electrode is 8-15 μm; in a specific embodiment, the point electrode is 10 μm; The material of the bottom electrode is conductive silver paste; the electrode thickness of the bottom electrode and the top electrode is 10-200nm; Said e The phase gallium oxide layer serves as both a ferroelectric layer and a photosensitive layer, with a thickness of 0.1 to 10 μm; The buffer layer is nickel oxide (111) and has a thickness of 1-50 nm.

[0025] The substrate material is silicon (111).

[0026] The preparation method specifically comprises the following steps: S1. Clean the substrate and place it in a magnetron sputtering growth chamber after cleaning. The cleaning process is as follows: soak the substrate in hydrofluoric acid to remove the natural silicon dioxide layer on the surface of the substrate, then ultrasonically clean the substrate in trichloroethylene, acetone, anhydrous ethanol, and deionized water in turn to remove organic matter adsorbed on the surface of the substrate; then blow dry the substrate with high-purity nitrogen gas and place the substrate in a magnetron sputtering growth chamber; S2. The buffer layer is grown on the substrate by magnetron sputtering. The specific operation is as follows: the growth chamber is pumped to the primary vacuum by a mechanical pump, and then the molecular pump is started to pump the vacuum to 7×10 -6 Torr, pre-sputtering to remove contamination on the target surface; the target is a nickel oxide ceramic target, the RF power is 130~180W, the gas pressure during sputtering is 0.3~1Pa, the oxygen flow rate is 10~15sccm, the argon flow rate is 5~10sccm, and the growth time is 10~30 minutes; S3. After the buffer layer is taken out, it is placed in the MOCVD reaction chamber for e Growth of phase gallium oxide layer; the organic gallium source is triethylgallium (TEGa), the cold trap setting temperature of the organic gallium source is 10°C, the selected oxygen source is high-purity oxygen, and the selected organic source carrier gas and booster gas are both 6-N high-purity nitrogen; Use a mechanical pump to evacuate the reaction chamber, then set the temperature of the heating base to heat the substrate; to avoid pre-reaction between the organic source and the sample before contact, adjust the substrate to the bottom of the spray device; after heating to the set temperature, pre-heat the substrate for 10 minutes, then set the gas pressure of the reaction chamber and introduce the organic source and reaction gas to start epitaxial growth; the growth pressure is 800Pa, the substrate temperature is 600~700ºC, the oxygen source flow rate is 400~800sccm, the gallium source flow rate is 4~8sccm, and the growth time is 100~150 minutes; S4. Applying a photoresist on the ε-phase gallium oxide layer, and forming a metal electrode pattern on the photoresist after pre-baking, exposure, post-baking, and development; S5. Deposit metal on the metal electrode pattern area by electron beam deposition; perform lift-off process, and obtain the top electrode after peeling; the deposition condition is room temperature, the metal target material is platinum, the pre-sputtering time is 1-3 minutes, and the deposition time is 10-30 minutes; the top electrode is a point electrode with a diameter of 8-15 μm; S6. The electrode material is uniformly coated on the surface of the substrate facing away from the buffer layer, and the bottom electrode is obtained after hot plate baking, thereby completing the preparation of the gallium oxide-based vertical structure ultraviolet detector.

[0027] Example 1 like Figure 1-Figure 2As shown, this embodiment provides a gallium oxide-based vertical structure ultraviolet detector, including a bottom electrode 105, a substrate 101, a buffer layer 102, e Phase gallium oxide layer 103 and point electrode 104; The material of the buffer layer 102 is nickel oxide (111) with a thickness of 1-50 nm; the substrate is a silicon (111) substrate; The point electrode 104 and the bottom electrode 105 are used to apply a bias voltage to achieve the e Gallium Oxide polarization deflection of layer 103; The top electrode 104 is a point electrode made of platinum; the diameter of the point electrode is 10 μm; The material of the bottom electrode 105 is conductive silver paste; the electrode thickness of the bottom electrode and the top electrode is 10-200 nm; e The thickness of the gallium oxide layer 103 is 0.1-10 μm.

[0028] The preparation method specifically comprises the following steps: S1. The substrate 101 is cleaned, and after cleaning, the substrate 101 is placed in a growth chamber of a magnetron sputtering; The specific operation is as follows: soak the silicon (111) substrate in 5% by mass hydrofluoric acid for 5 minutes to remove the natural silicon dioxide layer on the surface of the substrate, then ultrasonically clean it in trichloroethylene, acetone, anhydrous ethanol, and deionized water for 5 minutes in turn to remove the organic matter adsorbed on the surface of the silicon (111) substrate, and then blow dry the substrate with high-purity nitrogen; place the silicon (111) substrate in the growth chamber of magnetron sputtering.

[0029] S2. Growing a buffer layer 102 of nickel oxide (111) on the substrate 101; The specific operation is as follows: the growth chamber is evacuated to the primary vacuum degree by a mechanical pump, and then the molecular pump is started to evacuate the vacuum degree to 7×10 -6 Torr, using 10 minutes of pre-sputtering to remove contamination on the target surface; the target is a nickel oxide ceramic target with a purity of 99.99%, the RF power is 150W, the gas pressure during sputtering is 0.5Pa, the oxygen flow rate is 12sccm, the argon flow rate is 8sccm, and the growth time is 20 minutes.

[0030] S3. After the growth of the buffer layer 102 nickel oxide (111) is completed, it is taken out and placed in the MOCVD reaction chamber for e Growth of the gallium oxide layer 103; the specific operation is as follows: The organic gallium source is triethylgallium (TEGa), the cold trap temperature of the organic gallium source is set at 10°C, the oxygen source is high-purity oxygen, and the organic source carrier gas and booster gas are both 6-N high-purity nitrogen. During the growth process, the tail gas treatment system is used to treat the tail gas through physical adsorption or chemical adsorption to reduce the toxic substances to meet national standards. Use a mechanical pump to evacuate the reaction chamber, then set the temperature of the heating base to heat the substrate; to avoid pre-reaction between the organic source and the sample before contact, adjust the substrate to 6 cm below the spray device; after heating to the set temperature, preheat the substrate for 10 minutes, then set the gas pressure in the reaction chamber and introduce the organic source and reaction gas to start epitaxial growth; the growth pressure is 800 Pa, the substrate temperature is 630ºC, the oxygen source flow rate is 500sccm, the gallium source flow rate is 5.3sccm, and the growth time is 120 minutes.

[0031] S4. Apply photoresist on the ε-phase gallium oxide layer 103, and form a metal electrode pattern on the photoresist through pre-baking, exposure, post-baking, and development.

[0032] S5. Using an electron beam deposition method, depositing metal on the metal electrode pattern area; performing a lift-off process, and obtaining a point electrode 104 after peeling; the number of point electrodes 104 is 4; The deposition conditions are room temperature, the metal target is platinum, the pre-sputtering time is 2 minutes, and the deposition time is 20 minutes; the diameter of the point electrode 104 is 10 μm.

[0033] S6. A bottom electrode 105 is prepared on the surface of the substrate 101 facing away from the buffer layer 102, and a layer of silver paste is evenly coated on the electrode. After hot plate baking, the gallium oxide-based vertical structure UV detector is prepared (flow chart as shown in FIG. Figure 3 ). The three-dimensional schematic diagram of its structure is as follows Figure 1 .

[0034] Figure 4 The XRD diagram of the ε-phase gallium oxide layer is shown. It can be seen from the figure that the present invention can use the MOCVD method to grow a good quality e Phase gallium oxide. Figure 5 The SEM image of the ε-phase gallium oxide layer is shown. It can be seen from the figure that the e There are crystal particles on the surface of the phase gallium oxide film.

[0035] Brief description of the principle of the present invention: At present, the existing e Improve the quality of gallium oxide films to improve e phase GaO photodetector performance, without using ePhase gallium oxide has non-inversion symmetry along the c-axis and exhibits ferroelectric properties. In addition, silicon (111) as a conductive semiconductor has the advantages of low cost, high integration, and compatibility with CMOS integration processes, making it very suitable as e Phase gallium oxide-based solar-blind ultraviolet detector substrate material, but e There is a large lattice mismatch (up to about 24.2%) between the phase gallium oxide and silicon (111). The present invention proposes a method of inserting a buffer layer between the substrate silicon (111) layer and the gallium oxide layer to relax the lattice strain and reduce the lattice mismatch, thereby constructing e Phase-phase gallium oxide-based vertical structure solar-blind ultraviolet detector, polarization flipping of the material to induce internal electric field charge separation, e Research on polarization control of current in phase-converted gallium oxide thin films can effectively improve detector performance.

[0036] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0037] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A gallium oxide-based vertical structure ultraviolet detector, characterized in that: It includes a bottom electrode, a substrate, a buffer layer, ε phase gallium oxide layer and top electrode; The buffer layer is nickel oxide; the substrate is a silicon substrate; The top electrode and the bottom electrode are used to apply a bias voltage to achieve ε Polarization deflection of the phase gallium oxide layer.

2. The gallium oxide-based vertical structure ultraviolet detector according to claim 1, characterized in that: The buffer layer is nickel oxide (111), and the thickness of the buffer layer is 1-50 nm.

3. The gallium oxide-based vertical structure ultraviolet detector according to claim 1, characterized in that: Said ε The thickness of the phase gallium oxide layer is 0.1-10 μm; and the substrate is a silicon (111) substrate.

4. The gallium oxide-based vertical structure ultraviolet detector according to claim 1, characterized in that: The top electrode is a point electrode, and the material of the point electrode has a conductivity higher than 5×10 6 S / M, electrode material with strong adhesion.

5. The gallium oxide-based vertical structure ultraviolet detector according to claim 4, characterized in that: The diameter of the point electrode is 10 μm.

6. The gallium oxide-based vertical structure ultraviolet detector according to claim 5, characterized in that: The electrode thickness of the bottom electrode and the top electrode is 10-200 nm; the material of the top electrode is nickel, gold, titanium, platinum or conductive silver paste; the material of the bottom electrode is conductive silver paste.

7. The method for preparing a gallium oxide-based vertical structure ultraviolet detector according to any one of claims 1 to 6, characterized in that: The specific steps include: S1. Cleaning the substrate, and placing the substrate in a growth chamber of magnetron sputtering after cleaning; S2. growing a buffer layer on the substrate by magnetron sputtering; S3. After the buffer layer is taken out, it is placed in the MOCVD reaction chamber for ε Growth of phase gallium oxide layers; S4. Applying a photoresist on the ε-phase gallium oxide layer, and forming a metal electrode pattern on the photoresist after pre-baking, exposure, post-baking, and development; S5. Depositing metal on the metal electrode pattern region by electron beam deposition; performing a lift-off process to obtain a top electrode after peeling; S6. The electrode material is uniformly coated on the surface of the substrate facing away from the buffer layer, and the bottom electrode is obtained after hot plate baking, thereby completing the preparation of the gallium oxide-based vertical structure ultraviolet detector.

8. The method for preparing a gallium oxide-based vertical structure ultraviolet detector according to claim 7, characterized in that: In step S3 ε The growth temperature of the phase gallium oxide layer is 600~700°C, the growth time is 100~150 minutes, and the growth pressure is 750~850Pa.

9. The method for preparing a gallium oxide-based vertical structure ultraviolet detector according to claim 7, characterized in that: In the step S2, the radio frequency power of the magnetron sputtering is 130-180 W, the gas pressure during sputtering is 0.3-1 Pa, the oxygen flow rate is 10-15 sccm, the argon flow rate is 5-10 sccm, and the growth time is 10-30 minutes.

10. The method for preparing a gallium oxide-based vertical structure ultraviolet detector according to claim 7, characterized in that: The deposition temperature in step S4 is room temperature, the metal target is platinum, the pre-sputtering time is 1 to 5 minutes, and the deposition time is 15 to 25 minutes.

Images