Photoelectric detector based on metal-doped gallium oxide thin film and preparation method thereof

Abstract

The invention discloses a photoelectric detector based on a metal-doped gallium oxide thin film and a preparation method of the photoelectric detector, and belongs to the technical field of photoelectric device preparation. The detector sequentially comprises a sapphire substrate, a metal-doped gallium oxide thin film layer and a metal conductive electrode. Through the CVD technology, the metal-doped gallium oxide thin film material is enabled to grow freely, the grown metal-doped gallium oxide thin film is preferentially oriented, the crystallinity is high, and the preparation cost is extremely low. Moreover, post-annealing treatment is carried out on the metal-doped gallium oxide thin film, so that the crystallization quality of the thin film is improved, and high-purity oxygen atmosphere annealing further improves the crystallization quality of the metal-doped gallium oxide thin film. And oxygen atom dangling bonds on the surface of the metal-doped gallium oxide thin film are increased, so that Schottky is formed to reduce the dark current of the solar blind photoelectric detector.

Description

Technical Field

[0001] The present invention belongs to the technical field of photoelectric device preparation, and in particular relates to a metal-doped gallium oxide thin film photoelectric detector and a preparation method thereof. Background Art

[0002] Gallium Oxide 2 O 3 It is an ultra-wide bandgap transparent conductive semiconductor material with a bandgap width of 4.6 to 5.1 eV and a corresponding absorption cutoff edge of 240 to 270 nm, located in the solar-blind ultraviolet region (200 to 280 nm). Gallium oxide film has some special properties, which makes it potentially useful in electronics, optics and thermals. First, gallium oxide film has a high resistivity, which allows it to be used to prepare high-purity, low-noise electronic devices. Second, gallium oxide film has a direct bandgap and can be used in optoelectronic devices and solar cells. There are many methods for preparing gallium oxide film, including MOCVD, ALD, magnetron sputtering, pulsed laser deposition, electron beam evaporation, etc. These methods can control the composition, structure and thickness of the film, thereby obtaining a gallium oxide film with the desired properties.

[0003] The prior art uses a method of directly preparing a gallium oxide film on a substrate. However, the directly prepared gallium oxide film does not have a preferred orientation, and the gallium oxide film has low stability, insufficient crystallinity, and high preparation cost. In addition, the photodetector obtained based on the above gallium oxide film has a high dark current and a low switching ratio.

[0004] Based on the above reasons, this application is filed. Summary of the invention

[0005] Based on the above reasons, in view of the problems or defects in the prior art, the purpose of the present invention is to provide a metal-doped gallium oxide thin film photodetector and a preparation method thereof, which solves or at least partially solves the above technical defects in the prior art:

[0006] In order to achieve the above first object of the present invention, the technical solution adopted by the present invention is as follows:

[0007] A metal-doped gallium oxide thin film photoelectric detector comprises a sapphire substrate, a metal-doped gallium oxide thin film layer, and a metal conductive electrode in sequence.

[0008] Furthermore, in the above technical solution, the substrate is single-polished sapphire or double-polished sapphire; when the substrate is single-polished sapphire, the polished side of the substrate is placed upward. In a preferred embodiment of the present invention, the material of the substrate is c-plane (0001) double-polished sapphire.

[0009] Furthermore, in the above technical solution, the thickness of the metal-doped gallium oxide thin film layer is 1-10 microns; in a preferred embodiment of the present invention, the thickness of the metal-doped gallium oxide thin film layer is 4 microns.

[0010] Furthermore, in the above technical solution, the metal-doped gallium oxide film is prepared by the following method:

[0011] Gallium oxide powder, graphite powder, metal powder or metal oxide powder are mixed according to a ratio to obtain a reaction substrate; then the reaction substrate is placed in a quartz boat with uniform single gallium on the bottom, a sapphire substrate is placed directly above the quartz boat, and then the reaction substrate is transferred to a chemical vapor deposition (CVD) tube furnace, heated to 1000-1200° C. after gas is introduced, kept warm for 2-3 hours, and naturally cooled to room temperature; finally, fire treatment is performed in a high-purity oxygen atmosphere to obtain the metal-doped gallium oxide film.

[0012] Preferably, in the above technical solution, the molar ratio of the gallium oxide powder, the graphite powder, the metal powder or the metal oxide powder is 40:1:1.

[0013] Preferably, in the above technical solution, the metal includes any one or more of magnesium, zinc, indium, tin, cadmium, ytterbium, etc. In a preferred embodiment of the present invention, the metal is preferably zinc.

[0014] Preferably, in the above technical solution, the metal oxide includes any one or more of magnesium oxide, zinc oxide, indium oxide, tin oxide, tellurium oxide, etc.

[0015] Preferably, in the above technical solution, the gas includes a protective gas and a reactive gas, the protective gas is argon gas, and the gas flow rate is 150-250 sccm; the reactive gas is oxygen gas, and the flow rate is 0.1-1.0 sccm.

[0016] Preferably, in the above technical solution, the flow ratio of the protective gas to the reaction gas is 400:0.5 to 400:2.

[0017] Preferably, in the above technical solution, the heating rate is 30-40°C / min.

[0018] Preferably, in the above technical solution, the distance between the substrate and the reaction substrate is 0.5-1 cm.

[0019] Preferably, in the above technical solution, the annealing temperature is 750-850°C, and the annealing time is 30-60 minutes. In a preferred embodiment of the present invention, the annealing temperature is 800°C.

[0020] Specifically, in the above technical solution, the high-purity oxygen refers to pure oxygen with a concentration of 100%.

[0021] The second object of the present invention is to provide a method for preparing the above-mentioned metal-doped gallium oxide thin film photodetector, the method specifically comprising the following steps:

[0022] S1: Get the substrate and clean it;

[0023] S2: prepare reaction substrate;

[0024] S3: growing a metal-doped gallium oxide thin film layer on the surface of a sapphire substrate using a CVD process;

[0025] S4: Evaporation of metal electrodes.

[0026] Furthermore, in the above technical solution, the cleaning steps of the substrate are as follows: sapphire is selected as the substrate, and acetone, anhydrous ethanol and ultrapure water are used to ultrasonically clean the substrate in sequence.

[0027] Furthermore, in the above technical solution, the reaction substrate in step S2 is prepared by the following method, which comprises the following steps: mixing gallium oxide powder, graphite powder, metal powder or metal oxide powder according to a proportion to obtain a reaction substrate.

[0028] Furthermore, in the above technical solution, the metal-doped gallium oxide film in step S3 is prepared by the following method, the steps are as follows:

[0029] The reaction substrate is placed in a quartz boat with uniform single-element gallium on the bottom, a sapphire substrate is placed directly above the quartz boat, and then transferred together to a chemical vapor deposition (CVD) tube furnace, heated to 1000-1200° C. after passing gas, and kept warm for 2-3 hours, and naturally cooled to room temperature; finally, annealing treatment is performed in a high-purity oxygen atmosphere to obtain the metal-doped gallium oxide film.

[0030] Preferably, in the above technical solution, the molar ratio of the gallium oxide powder, the graphite powder, the metal powder or the metal oxide powder is 40:1:1.

[0031] Preferably, in the above technical solution, the metal includes any one or more of magnesium, zinc, indium, tin, cadmium, ytterbium, etc.

[0032] Preferably, in the above technical solution, the metal oxide includes any one or more of magnesium oxide, zinc oxide, indium oxide, tin oxide, tellurium oxide, etc.

[0033] Preferably, in the above technical solution, the gas includes a protective gas and a reactive gas, the protective gas is argon gas, and the gas flow rate is 150-250 sccm; the reactive gas is oxygen gas, and the flow rate is 0.1-1.0 sccm.

[0034] Preferably, in the above technical solution, the flow ratio of the protective gas to the reaction gas is 400:0.5 to 400:2.

[0035] Preferably, in the above technical solution, the heating rate is 30-40°C / min.

[0036] Preferably, in the above technical solution, the distance between the substrate and the reaction substrate is 0.5-1 cm.

[0037] Preferably, in the above technical solution, the annealing temperature is 750-850°C, and the annealing time is 30-60 minutes. In a preferred embodiment of the present invention, the annealing temperature is 800°C.

[0038] Furthermore, in the above technical solution, the evaporated metal electrode in step S4 is prepared by the following method, which comprises placing an interdigitated electrode mask on the metal-doped gallium oxide film, placing the mask in a metal evaporator, and evaporating metal to form a metal electrode.

[0039] Preferably, in the above technical solution, the metal electrode is

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) The present invention allows the metal-doped gallium oxide thin film material to "grow freely" through the CVD process. The grown metal-doped gallium oxide thin film has a preferred orientation, high crystallinity, and extremely low preparation cost.

[0042] (2) The present invention performs post-annealing treatment on the metal-doped gallium oxide film to improve the crystallization quality of the film. Annealing in a high-purity oxygen atmosphere further improves the crystallization quality of the metal-doped gallium oxide film, and increases the oxygen atom dangling bonds on the surface of the metal-doped gallium oxide film to form Schottky to reduce the dark current of the solar-blind photodetector. The present invention grows the metal-doped gallium oxide film through a CVD tube furnace, further reducing the preparation cost of high-performance gallium oxide film. The solar-blind photodetector prepared by this method has an ultra-high switching ratio, excellent detection and responsiveness, and extremely low response time. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1A schematic diagram of the process of preparing a metal-doped gallium oxide film according to the present invention;

[0045] Figure 2 A schematic diagram for placing reaction substrates;

[0046] Figure 3 This is a voltage-current performance diagram of a solar-blind photodetector based on zinc-doped gallium oxide thin film prepared in Example 1 of the present invention;

[0047] Figure 4 The cross-sectional view and the plan view of the zinc-doped gallium oxide thin film prepared in Example 1 of the present invention;

[0048] Figure 5 This is a voltage-current performance diagram of a solar-blind photodetector based on a gallium oxide thin film prepared in Example 2 of the present invention;

[0049] Figure 6 A cross-sectional view and a plan view of a gallium oxide thin film prepared in Example 2 of the present invention;

[0050] Figure 7 The voltage-current performance diagram of the solar-blind photodetector based on zinc-doped gallium oxide thin film prepared in Comparative Example 1;

[0051] Figure 8 This is a cross-sectional view of the zinc-doped gallium oxide thin film prepared in Comparative Example 1. DETAILED DESCRIPTION

[0052] The present invention is further described in detail below through implementation cases. This implementation case is implemented based on the technology of the present invention, and a detailed implementation method and specific operation process are now given to illustrate that the present invention is creative, but the protection scope of the present invention is not limited to the following implementation cases.

[0053] According to the information contained in this application, various changes can be easily made to the precise description of the present invention for those skilled in the art.It should be understood that the scope of the present invention is not limited to defined processes, properties or components, because these embodiments and other descriptions are only for illustrating specific aspects of the present invention.

[0054] In order to better understand the present invention but not to limit the scope of the present invention, all the numbers used in this application to express the amount, percentage, and other numerical values ​​should be understood as modified by the word "about" in all cases. Therefore, unless otherwise specified, the numerical parameters listed in the specification are approximate values, which may be changed according to the different ideal properties attempted to be obtained. Each numerical parameter should at least be regarded as obtained based on the reported significant figures and by conventional rounding methods.

[0055] The equipment and raw materials used in the present invention can be purchased from the market or are commonly used in the art. The methods in the following embodiments are all conventional methods in the art unless otherwise specified.

[0056] Example 1

[0057] See also Figure 1 , Figure 1 It is a schematic diagram of the steps of a method for preparing a gallium oxide thin film provided in an embodiment of the present invention.

[0058] A method for preparing a zinc-doped gallium oxide thin film solar-blind photodetector provided by an embodiment of the present invention comprises the following steps:

[0059] S1: Get the lining and clean it

[0060] Select c-plane sapphire (0001) as the substrate. The lattice structure of sapphire (0001) and gallium oxide is relatively close, and the grown gallium oxide film has low dislocation and better crystal quality. Put the sapphire (0001) into the slot, pour enough acetone organic solution to immerse the slot into the beaker, put the slot into the beaker, and immerse the sapphire (0001) completely in it. Then, use ultrasonic cleaning for 20 minutes. Then, take out the slot from the acetone solution, put it into an anhydrous ethanol solution that can immerse the slot, and use ultrasonic cleaning for 20 minutes. The same operation is put into ultrapure water for ultrasonic cleaning for 20 minutes. After the cleaning is completed, take out the slot and blow dry the sapphire with nitrogen.

[0061] S2: Prepare reaction substrate

[0062] Gallium oxide powder, graphite powder and zinc powder are mixed uniformly according to a ratio to obtain the reaction substrate; wherein the molar ratio of the gallium oxide, graphite powder and zinc powder is 40:1:1.

[0063] S3: Place the reaction substrate into a CVD tube furnace to grow zinc metal-doped gallium oxide thin films

[0064] 1 g of single gallium was evenly spread on the bottom of the quartz boat, and then the reaction substrate was placed in the quartz boat with the single gallium evenly spread on the bottom. The c-plane sapphire substrate treated in step S1 was horizontally placed on the quartz boat at a distance of 5 mm from the reaction substrate, and transferred to a chemical vapor deposition (CVD) tube furnace (the specific placement position is as shown in Figure 2 As shown), gas was introduced for 30 minutes to remove the air in the quartz tube, and then the temperature was raised to 1100°C in 30 minutes, kept at this temperature for 2 hours, and naturally cooled to room temperature; wherein:

[0065] The gas includes a protective gas and a reactive gas. The protective gas is argon gas with a gas flow rate of 200 sccm; the reactive gas is oxygen gas with a flow rate of 0.5 ccm.

[0066] S4: Post-annealing in a high-purity oxygen atmosphere

[0067] Pure oxygen with a concentration of 100% was introduced into the tube furnace, and then the temperature was raised to 800° C. at a heating rate of 10° C. / min and kept at that temperature for 1 hour to obtain a zinc metal-doped gallium oxide film with a thickness of 4 μm.

[0068] S5: placing an interdigitated electrode mask on the surface of the zinc metal-doped gallium oxide film obtained in S4, placing it in a metal evaporator, evaporating gold to form a metal electrode.

[0069] like Figure 3 The electrical properties of the zinc-doped gallium oxide thin film photodetector prepared in Example 1 are shown. The dark current (dark current) was measured using a KEITHLEY 4200A semiconductor tester. The dark current was measured using 0.5, 10, 20, 40, 60, 80, 100, and 5000 μw / cm 2 The day-blind band light is irradiated on the surface of the photodetector. At this time, the current of the photodetector is measured as the photocurrent. Under the bias voltage of 37V, the dark current is still as low as 10 -11 ~10 -12 A, photocurrent up to 1×10 -3 A, achieved about 10 9 Ultra-high on / off ratio. And at 0.5μw / cm 2 Even at very low light intensity, it still shows 10 6 Extremely high on / off ratio. Can be used under extreme conditions in real environments and has good application prospects.

[0070] like Figure 4 The surface and cross-sectional SEM images of the zinc-doped gallium oxide prepared in Example 1 are shown. It can be seen that the surface of the gallium oxide film is flat, the interior is dense and has no voids, and the film quality is very good.

[0071] In this embodiment, the reaction of the single-element gallium layer laid on the bottom of the quartz boat may be as follows:

[0072] Ga 2 O 3 (s)+2C(s)→Ga 2 O(v)+2CO(g) (1)

[0073] Ga 2 O 3 (s)+3C(s)→2Ga(v)+3CO(g) (2)

[0074] 2Ga 2 O(v)+2Zn(v)+3O 2 (s)→2ZnGa 2O 4 (s) (3)

[0075] 2Ga(v)+Zn(v)+2O 2 (S)→ZnGa 2 O 4 (s) (4)

[0076] Gallium mainly catalyzes the reactions in steps (1) and (2). Gallium evaporates very slowly at 1100°C. Gallium at the bottom evaporates into gallium vapor and begins to diffuse evenly into the reaction substrate, reducing the activation energy of the reactions in steps (1) and (2), making it easier for the raw material molecules to reach an activated state and react. It also makes the gallium molecules obtained by reducing gallium oxide in the second step more volatile, promoting the reaction in step (4). According to experimental observations, if single gallium is not placed at the bottom, the activation energy required for the reaction is higher, and carbon tends to react with oxygen, resulting in experimental failure.

[0077] Example 2

[0078] A method for preparing a solar-blind photodetector based on a gallium oxide thin film provided in an embodiment of the present invention comprises the following steps:

[0079] S1: Get the lining and clean it

[0080] Select c-plane sapphire (0001) as the substrate. The lattice structure of sapphire (0001) and gallium oxide is relatively close, and the grown gallium oxide film has low dislocation and better crystal quality. Put the sapphire (0001) into the slot, pour enough acetone organic solution to immerse the slot into the beaker, put the slot into the beaker, and immerse the sapphire (0001) completely in it. Then, use ultrasonic cleaning for 20 minutes. Then, take out the slot from the acetone solution, put it into an anhydrous ethanol solution that can immerse the slot, and use ultrasonic cleaning for 20 minutes. The same operation is put into ultrapure water for ultrasonic cleaning for 20 minutes. After the cleaning is completed, take out the slot and blow dry the sapphire with nitrogen.

[0081] S2: Prepare reaction substrate

[0082] Gallium oxide powder and graphite powder are mixed evenly according to a ratio to obtain the reaction substrate; wherein the molar ratio of the gallium oxide to the graphite powder is 40:1.

[0083] S3: Place the reaction substrate into a CVD tube furnace to grow a gallium oxide film

[0084] 1 g of single gallium was evenly spread on the bottom of the quartz boat, and then the reaction substrate was placed in the quartz boat with the single gallium evenly spread on the bottom. The c-plane sapphire substrate treated in step S1 was horizontally placed on the quartz boat at a distance of 5 mm from the reaction substrate, and transferred to a chemical vapor deposition (CVD) tube furnace (the specific placement position is as shown in Figure 2 As shown), gas was introduced for 30 minutes to remove the air in the quartz tube, and then the temperature was raised to 1100°C in 30 minutes, kept at this temperature for 2 hours, and naturally cooled to room temperature; wherein:

[0085] The gas includes a protective gas and a reactive gas. The protective gas is argon gas with a gas flow rate of 200 sccm; the reactive gas is oxygen gas with a flow rate of 0.5 sccm.

[0086] S4: Post-annealing in a high-purity oxygen atmosphere

[0087] Pure oxygen with a concentration of 100% was introduced into the tube furnace, and then the temperature was increased to 800°C at a heating rate of 10°C / min and kept at that temperature for 1 hour.

[0088] S5: Place an interdigitated electrode mask on the surface of the gallium oxide film obtained in S4, put it into a metal evaporator, evaporate gold, and form a metal electrode.

[0089] like Figure 5 The electrical performance of the undoped gallium oxide thin film photodetector prepared in Example 2 is shown as follows. 7 The on / off ratio of the photodetector based on zinc-doped gallium oxide thin film prepared in Example 1 is significantly lower than that of the photodetector based on zinc-doped gallium oxide thin film prepared in Example 1. 2 At very low light intensities, it exhibits 10 4 The on / off ratio is also significantly lower than that of Example 1.

[0090] like Figure 6 Shown are the SEM images of the gallium oxide surface and cross section of the gallium oxide film prepared in Example 2. It can be seen that the surfaces of the undoped gallium oxide film and the zinc-doped gallium oxide film are both flat, the interior is dense, and the film quality is very good.

[0091] The function of the single gallium laid at the bottom in Example 2 is as follows:

[0092] Ga 2 O 3 (s)+2C(s)→Ga 2 O(v)+2CO(g) (1)

[0093] Ga 2 O 3 (s)+3C(s)→2Ga(v)+3CO(g) (2)

[0094] Ga 2 O(v)+2O 2 (s)→Ga 2 O 3 (s) (3)

[0095] 4Ga(s)+3O 2 (s)→2Ga 2 O 3 (s) (4)

[0096] Gallium mainly catalyzes the reactions in steps (1) and (2). Gallium evaporates very slowly at 1100 degrees. Gallium at the bottom evaporates into gallium vapor and begins to diffuse evenly into the reaction substrate, reducing the activation energy of the reactions in steps (1) and (2), making it easier for the raw material molecules to reach an activated state and react. It also makes the gallium molecules obtained by reducing gallium oxide in the second step more volatile, promoting the reaction in step (4). According to experimental observations, if single gallium is not placed at the bottom, the activation energy required for the reaction is higher, and carbon tends to react with oxygen, resulting in experimental failure.

[0097] Comparative Example 1

[0098] The preparation method of a zinc-doped gallium oxide film in this comparative example is the same as that in Example 1, except that the flow ratio of the protective gas argon and the reaction gas oxygen in this comparative example is 400:2, while the flow ratio of the protective gas argon and the reaction gas oxygen used in Example 1 is 400:1, that is, 200 sccm argon + 1 sccm oxygen is used in this comparative example.

[0099] Furthermore, the method for preparing the solar-blind photodetector in this comparative example is substantially the same as that in Example 1, except that the zinc-doped gallium oxide thin film prepared by the above method in this comparative example is used in this comparative example.

[0100] Depend on Figure 7 , 8, it can be seen that the switching ratio and dark current of the day-blind photodetector of comparative example 1 are significantly different from those of embodiment 1, and the film quality is worse than that of embodiment 1. It can be seen that the flow rate of argon: oxygen = 400: 1 is better.

Claims

1. A metal-doped gallium oxide thin film photodetector, characterized in that: The detector comprises a sapphire substrate, a metal-doped gallium oxide thin film layer, and a metal conductive electrode in sequence; the thickness of the metal-doped gallium oxide thin film layer is 1-10 microns; the metal comprises any one or more of magnesium, zinc, indium, tin, cadmium, and ytterbium.

2. The metal-doped gallium oxide thin film photodetector according to claim 1, characterized in that: The metal-doped gallium oxide film is prepared by the following method: Gallium oxide powder, graphite powder, metal powder or metal oxide powder are mixed according to a ratio to obtain a reaction substrate; then the reaction substrate is placed in a quartz boat with uniform single gallium on the bottom, a sapphire substrate is placed directly above the quartz boat, and then the reaction substrate is transferred to a chemical vapor deposition CVD tube furnace, after gas is introduced, the temperature is raised to 1000-1200° C. and kept at this temperature for 2-3 hours, and then naturally cooled to room temperature; finally, a fire treatment is performed in a high-purity oxygen atmosphere to obtain the metal-doped gallium oxide film.

3. The metal-doped gallium oxide thin film photodetector according to claim 2, characterized in that: The molar ratio of the gallium oxide powder, the graphite powder, the metal powder or the metal oxide powder is 40:1:

1.

4. The metal-doped gallium oxide thin film photodetector according to claim 2, characterized in that: The gas includes a protective gas and a reactive gas. The protective gas is argon gas with a gas flow rate of 150-250 sccm; the reactive gas is oxygen gas with a flow rate of 0.1-1.0 sccm.

5. The metal-doped gallium oxide thin film photodetector according to claim 4, characterized in that: The flow ratio of the protective gas to the reaction gas is 400:0.5 to 400:

2.

6. The metal-doped gallium oxide thin film photodetector according to claim 2, characterized in that: The heating rate is 30-40°C / min.

7. The metal-doped gallium oxide thin film photodetector according to claim 2, characterized in that: The distance between the substrate and the reaction substrate is 0.5-1 cm.

8. The metal-doped gallium oxide thin film photodetector according to claim 2, characterized in that: The annealing temperature is 750-850° C., and the annealing time is 30-60 minutes.

9. The method for preparing a metal-doped gallium oxide thin film photodetector according to claim 1, characterized in that: The method specifically comprises the following steps: S1: Get the substrate and clean it; S2: prepare reaction substrate; S3: growing a metal-doped gallium oxide thin film layer on the surface of a sapphire substrate using a CVD process; S4: Evaporation of metal electrodes.

10. The preparation method according to claim 9, characterized in that: The metal includes any one or more of magnesium, zinc, indium, tin, cadmium, and ytterbium; the metal oxide includes any one or more of magnesium oxide, zinc oxide, indium oxide, tin oxide, and tellurium oxide.

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