Method for preparing Mg-doped gallium oxide thin film and Mg-doped gallium oxide solar-blind ultraviolet photoelectric detector

Abstract

The invention relates to a method for preparing an Mg-doped gallium oxide (Ga2O3) thin film and an Mg-doped gallium oxide solar-blind ultraviolet photoelectric detector. The method comprises the following steps: providing a precursor solution containing a magnesium source and a gallium source; preparing an epitaxial layer on a substrate by using the precursor solution as a raw material through a spin-coating method to obtain the substrate with the epitaxial layer; the substrate with the epitaxial layer is annealed under the condition of 150-250 DEG C and then cooled to the room temperature; sequentially repeating the steps S2-S3 for 1-10 times to obtain a substrate with an epitaxial layer; and annealing the substrate with the epitaxial layer at the temperature of 550-750 DEG C to obtain the Mg-doped gallium oxide thin film. According to the novel method for preparing the Mg-doped gallium oxide film, the Mg-doped Ga2O3 film is prepared through a solution method, expensive equipment and a harsh growth environment are not needed, the Mg-doped gallium oxide Ga2O3 film can be prepared in the air atmosphere, preparation of the Mg-doped gallium oxide film is simplified, and the preparation cost is reduced.

Description

Technical Field

[0001] The invention relates to a method for preparing a Mg-doped gallium oxide film and a Mg-doped gallium oxide solar-blind ultraviolet photodetector, and in particular to a method for preparing a Mg-doped gallium oxide film and a Mg-doped gallium oxide solar-blind ultraviolet photodetector based on a solution method, and belongs to the field of photoelectric devices. Background Art

[0002] With the advancement of artificial intelligence and automation, achieving automatic recognition and calculation has become the goal pursued by the development of the new generation of science and technology. Photoelectric detection technology is the first task to be solved. It plays an important role in display and imaging, optical communication, remote sensing, biomedicine and other fields.

[0003] As a representative of the third generation of semiconductors, Ga2O3 has an intrinsically extremely wide band gap, an ultra-wide optical band gap of about 4.9 eV, and its corresponding light response band is located in the solar-blind ultraviolet band UVC, which can effectively shield the influence of solar radiation and artificial light sources. Therefore, it is suitable for solar-blind photodetectors with λ≤280nm. Ga2O3 has five crystal forms: α, β, γ, δ and ε, among which β-Ga2O3 is the most stable phase. However, due to the presence of shallow donors of oxygen vacancies, β-Ga2O3 always exhibits n-type semiconductor behavior. For applications, p-type β-Ga2O3 films are indispensable, however, the preparation of p-type β-Ga2O3 films is still challenging, mainly due to the lack of suitable dopants (like other oxide semiconductors) and overcompensation of oxygen vacancies. Theoretically, Mg 2+ 、Zn 2+ 、Be 2+ Divalent ions replace trivalent Ga 3+ The position of p-type β-Ga2O3 can be achieved, but the current doping methods are mostly through magnetron sputtering and chemical vapor deposition and other technologies, which require expensive equipment and harsh growth environment, have high requirements on the operation of the preparation process, and the actual preparation cost is high.

[0004] Chinese invention patent application CN201610785354.0 discloses a zero-power solar-blind ultraviolet detector based on Mg:β-Ga2O3 / NSTO heterojunction and its preparation method, which specifically refers to the use of laser molecular beam epitaxy technology to deposit a layer of magnesium-doped β-Ga2O3 film on an NSTO single crystal substrate, and then using a mask and radio frequency magnetron sputtering technology to deposit a layer of titanium / gold film on the magnesium-doped gallium oxide film as a light-transmitting electrode, and using mechanical force to emboss In electrodes on the Ti / Au electrode and the substrate as the upper electrode and the lower electrode, respectively, to prepare the Mg:β-Ga2O3 / NSTO heterojunction solar-blind ultraviolet detection device. Although this preparation method can obtain a dense and uniform film, it requires the use of laser molecular beam epitaxy technology and radio frequency magnetron sputtering technology, the process is relatively complicated, and the equipment requirements are high, and the preparation cost is high, which limits its promotion and application. Summary of the invention

[0005] In view of the shortcomings of the prior art, an object of the present invention is to provide a method for preparing Mg-doped gallium oxide thin film with lower requirements on production equipment; a second object of the present invention is to provide a method for preparing Mg-doped gallium oxide (Ga2O3) day-blind ultraviolet photodetector to reduce the requirements on production equipment.

[0006] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0007] A method for preparing a Mg-doped gallium oxide thin film comprises the following steps:

[0008] S1. providing a precursor solution containing a soluble magnesium source and a soluble gallium source;

[0009] S2, using the precursor solution as a raw material, preparing an epitaxial layer on a substrate by spin coating to obtain a substrate with an epitaxial layer;

[0010] S3, annealing the substrate with the epitaxial layer at 150-250° C., and cooling to room temperature;

[0011] S4, repeat S2-S3 1-10 times in sequence to obtain a substrate with an epitaxial layer;

[0012] wherein, when S2 is repeated, an epitaxial layer is prepared on the substrate by spin coating on the same side of the substrate;

[0013] S5, annealing the substrate with the epitaxial layer obtained in S4 at 550-750° C. to obtain a Mg-doped gallium oxide thin film.

[0014] Thus, the present application uses the precursor solution as a raw material, prepares an epitaxial layer by spin coating, performs pre-annealing, repeats spin coating and pre-annealing, and obtains an epitaxial layer with a desired thickness and uniformity, and then obtains a Mg-doped gallium oxide film with excellent performance after annealing. In the preparation process of the present invention, no laser molecular beam epitaxy equipment or radio frequency magnetron sputtering equipment is required, and the preparation of the Mg-doped gallium oxide film can be completed by using common spin coating equipment and annealing furnace, which can effectively reduce the requirements for production equipment, help simplify the preparation process, and reduce the preparation cost.

[0015] Further, in S1, the soluble magnesium source is one or more of magnesium chloride, magnesium acetylacetonate, magnesium nitrate and their hydrates; the soluble gallium source is one or more of gallium chloride, gallium acetylacetonate, gallium nitrate and their hydrates; preferably, the solvent of the precursor solution is deionized water and / or an organic solvent; more preferably, the organic solvent includes one or more of ethanol, isopropanol, and 2-methoxyethanol (2-ME).

[0016] Optionally, the soluble magnesium source, the soluble gallium source and the solvent are mixed uniformly to obtain a precursor solution. Optionally, the mixture is mixed uniformly by magnetic stirring.

[0017] Further, in S1, in the precursor solution, the molar ratio of magnesium to gallium is 2-20:80-98, preferably 8-12:88-92; preferably, the concentration of magnesium is 0.04-0.06 mol / L. The applicant has repeatedly found that controlling the molar ratio of magnesium to gallium within a specific range is helpful to obtain a Mg-doped gallium oxide film with more outstanding performance.

[0018] Optionally, before S2, the substrate is surface cleaned and subjected to ultraviolet irradiation treatment.

[0019] Further, in S2, an epitaxial layer is prepared on a substrate by spin coating; preferably, when preparing the epitaxial layer, after dripping a precursor solution in the center of the substrate, the substrate is first controlled to spin at a rate of 800-1200rpm for 5-15s, and then the substrate is controlled to spin at a rate of 2500-3500rpm for 20-40s to obtain a substrate with an epitaxial layer; more preferably, the amount of the precursor solution added is 30-80μL, more preferably 40-70μL, and more preferably 50-60μL; preferably, spin coating is performed by a desktop glue spreader; preferably, the material of the substrate is sapphire. Preferably, after dripping a precursor solution in the center of the substrate, wait for 10-30s, then control the substrate to spin at a rate of 800-1200rpm for 5-15s, and then control the substrate to spin at a rate of 2500-3500rpm for 20-40s to obtain a substrate with an epitaxial layer.

[0020] Furthermore, in S3, the annealing temperature is 175-225°C, preferably 180-220°C.

[0021] Furthermore, in S3, the annealing time is 10-50 min, preferably 15-45 min, and more preferably 20-40 min.

[0022] Further, in S4, S2-S3 are repeated sequentially 2-8 times, preferably 3-7 times, and more preferably 4-6 times.

[0023] Furthermore, in S5, the annealing temperature is 575-725°C, preferably 600-700°C, and more preferably 625-675°C.

[0024] Furthermore, in S5, the annealing time is 1-3 h, preferably 1.25-2.75 h, and more preferably 1.5-2.5 h.

[0025] Optionally, annealing is performed in a muffle furnace.

[0026] Based on the same inventive concept, the present invention also provides a method for preparing a Mg-doped gallium oxide solar-blind ultraviolet photodetector, comprising the following steps:

[0027] (1) preparing a Mg-doped gallium oxide thin film on a sapphire substrate by the method described above;

[0028] (2) Preparing a gold electrode on the Mg-doped gallium oxide film obtained in step (1) to obtain a Mg-doped gallium oxide solar-blind ultraviolet photodetector.

[0029] Preferably, the material of the substrate is one of sapphire (α-Al2O3), gallium nitride (GaN), and gallium oxide (Ga2O3). Optionally, a gold (Au) electrode is prepared by a deposition method on the Mg-doped gallium oxide film obtained in step (1). Further, the deposition method is a sputtering method. Furthermore, the Au electrode is sputtered and deposited using a metal mask.

[0030] The present invention dopes Mg into a β-Ga2O3 film by a solution method, and the prepared Mg-doped Ga2O3 day-blind ultraviolet photodetector has good photoelectric performance, and its responsivity, light-to-dark current ratio and sensitivity are better than those of undoped Ga2O3 photodetector devices.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The present invention proposes a new method for preparing Mg-doped gallium oxide thin films, namely, preparing Mg-doped Ga2O3 thin films by a solution method, without the need for expensive equipment and harsh growth environment, and the Mg-doped gallium oxide Ga2O3 thin films can be prepared in an air atmosphere, which helps to simplify the preparation process and operation precision requirements of the Mg-doped gallium oxide thin films and reduce the preparation costs.

[0033] (2) The present invention prepares a Mg-doped gallium oxide thin film by spin coating, and further prepares a top electrode to obtain a Mg-doped gallium oxide solar-blind ultraviolet photodetector. The absorption spectrum wavelength range of the Mg-doped gallium oxide solar-blind ultraviolet photodetector is 200nm-280nm, and its device performance such as responsiveness, light-to-dark current ratio, and detection rate are relatively excellent, achieving high-performance detection of ultraviolet rays in the solar-blind ultraviolet band, and solving the problem of difficulty in device preparation faced in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The present invention is a flow chart for preparing a Mg-doped gallium oxide solar-blind ultraviolet photodetector.

[0035] Figure 2 It is a schematic structural diagram of a Mg-doped gallium oxide solar-blind ultraviolet photodetector of the present invention.

[0036] Figure 3 This is the X-ray diffraction (XRD) detection diagram of Ga2O3 thin films with different Ma doping amounts in the present invention.

[0037] FIG4 is a scanning electron microscope (SEM) characterization image of the Mg-doped Ga2O3 film prepared in Example 1 of the present invention, wherein: Figure 4a This is the SEM image under the condition of 20k times magnification. Figure 4b This is a SEM image at 50k times magnification.

[0038] Figure 5 These are the transmission spectrum detection results of the Mg-doped gallium oxide solar-blind ultraviolet photodetector with different Mg doping amounts in the present invention.

[0039] Figure 6 The results are a comparison of the performance parameters of the light-to-dark current ratio (PDCR) and the responsivity (R) of the gallium oxide solar-blind ultraviolet photodetector with different Mg doping amounts in the present invention. DETAILED DESCRIPTION

[0040] The present invention will be described in detail below in conjunction with the embodiments. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. Unless otherwise specified, the relevant percentages refer to mass percentages.

[0041] Example 1

[0042] The method for preparing the Mg-doped Ga2O3 thin film based on the solution method of this embodiment specifically includes the following steps:

[0043] S1: Configuration containing Mg 2+ Ga(NO3)3 precursor solution;

[0044] Among them, Mg 2+ Mg 2+ and Ga 3+ 5 mol% of the sum of the molar numbers of

[0045] Specifically, 15.25 mg of hydrated magnesium chloride (MgCl2·6H2O) and 595.28 mg of hydrated gallium nitrate (Ga(NO3)3·xH2O, molecular weight 417.74) were weighed on an electronic balance and mixed in a clean glass bottle. Filtered 2-methoxyethanol (2-ME) was measured and dripped into the clean glass bottle, and stirred until there was no obvious precipitation to prepare a precursor solution with a total volume of 3 mL. A clean magnet was then added, and the glass bottle was placed on a constant temperature magnetic stirrer, the temperature was set to 60°C and the speed was set to 2000 rpm. After stirring for 2 hours, it was allowed to stand for 24 hours to obtain a precursor solution for standby use.

[0046] S2: The sapphire substrate is surface cleaned and subjected to ultraviolet irradiation treatment.

[0047] Specifically, the substrate is ultrasonically cleaned in acetone, anhydrous ethanol and deionized water for 5 minutes in sequence, and after the washed substrate is dried, it is subjected to ultraviolet irradiation for 80 minutes.

[0048] S3: A Ga2O3 thin film epitaxial layer is grown on the cleaned substrate using a spin coating method.

[0049] Specifically, the forward rotation time of the desktop glue machine is set to 10s and the speed is 1000rpm, and the backward rotation time is 30s and the speed is 3000rpm. Place the UV-treated substrate on the glue machine suction cup, click the suction piece to fix the substrate, then use a pipette to absorb 50μL of the precursor solution obtained in step S1, drop it in the center of the substrate, wait for 20s and then start the glue machine. Then transfer it to a constant temperature table for pre-annealing, the annealing temperature is 200℃, the annealing time is 30min, and after cooling to room temperature, repeat the glue-pre-annealing-cooling operation 5 times. In the whole process, the glue-pre-annealing-cooling operation is performed a total of 6 times.

[0050] S4: The substrate with the Ga2O3 thin film epitaxial layer obtained in step S3 is transferred to a muffle furnace for high-temperature annealing at a temperature of 650° C. for 2 h to obtain a Mg-doped Ga2O3 thin film.

[0051] The relevant test results of the Mg-doped Ga2O3 film prepared in this example are as follows Figure 3 As shown in Figure 4, Figure 3 is an X-ray diffraction (XRD) detection diagram of the Mg-doped Ga2O3 film, from which it can be seen that the Mg-doped Ga2O3 film has good crystallization quality and contains β-Ga2O3; Figure 4 is a scanning electron microscope (SEM) characterization diagram of the prepared Mg-doped Ga2O3 film, from which it can be seen that the microscopic surface morphology of the Mg-doped Ga2O3 film is uniform.

[0052] Comparative Example 1

[0053] Example 1 was repeated, except that in S1, Mg 2+ Mg 2+ and Ga 3+ 0 mol% of the sum of the molar numbers of (ie, no hydrated magnesium chloride is added).

[0054] Example 2

[0055] Example 1 was repeated, except that in S1, Mg 2+ Mg 2+ and Ga 3+ 2 mol% of the sum of the molar numbers of

[0056] Example 3

[0057] Example 1 was repeated, except that in S1, Mg 2+ Mg 2+ and Ga 3+ 10 mol% of the sum of the molar numbers of

[0058] Example 4

[0059] Example 1 was repeated, except that in S1, Mg 2+ Mg 2+ and Ga 3+ 15 mol% of the sum of the molar numbers of

[0060] Example 5

[0061] Example 1 was repeated, except that in S1, Mg 2+ Mg 2+ and Ga 3+ 20 mol% of the sum of the molar numbers of

[0062] Examples 6-10, Comparative Example 2

[0063] This case provides a method for preparing a gallium oxide solar-blind ultraviolet photodetector. Figure 1 The present invention provides a flow chart for preparing a Mg-doped gallium oxide solar-blind ultraviolet photodetector. Figure 2 It is a schematic structural diagram of a Mg-doped gallium oxide solar-blind ultraviolet photodetector of the present invention.

[0064] The specific preparation method is as follows: on the basis of Examples 1-5 and Comparative Example 1, each further comprises step S5: depositing a gold (Au) electrode on the Ga2O3 film after high temperature annealing in step S4 by sputtering using a metal mask, wherein the channel width is 1 mm and the length is 0.2 mm. Finally, the gallium oxide solar-blind ultraviolet photodetector prepared by the solution method is obtained.

[0065] Figure 5 The transmission spectrum detection results of the gallium oxide solar-blind ultraviolet photodetector are shown, indicating that the absorption spectrum wavelength range of the Mg-doped gallium oxide solar-blind ultraviolet photodetector is 200nm-280nm. Figure 6 As shown in the figure, compared with the undoped Mg Ga2O3 device, its device performance such as responsiveness and light-to-dark current ratio is better, achieving high-performance detection of ultraviolet light in the solar-blind ultraviolet band. 2+ Mg 2+ and Ga 3+ When the content of Mg-doped gallium oxide is 2-10 mol% of the sum of the molar numbers of Mg, the performances such as the response and light-to-dark current ratio of the corresponding Mg-doped gallium oxide day-blind ultraviolet photodetector are significantly more outstanding.

[0066] The contents explained in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

Claims

1. A method for preparing a Mg-doped gallium oxide thin film, characterized in that: The steps include: S1. providing a precursor solution containing a soluble magnesium source and a soluble gallium source; S2, using the precursor solution as a raw material, preparing an epitaxial layer on a substrate by spin coating to obtain a substrate with an epitaxial layer; S3, annealing the substrate with the epitaxial layer at 150-250° C., and cooling to room temperature; S4, repeat S2-S3 1-10 times in sequence to obtain a substrate with an epitaxial layer; wherein, when S2 is repeated, an epitaxial layer is prepared on the substrate by spin coating on the same side of the substrate; S5. Annealing the substrate with the epitaxial layer obtained in S4 at 550-750° C. to obtain a Mg-doped gallium oxide film.

2. The method according to claim 1, characterized in that: In S1, the soluble magnesium source is one or more of magnesium chloride, magnesium acetylacetonate, magnesium nitrate and their hydrates; the soluble gallium source is one or more of gallium chloride, gallium acetylacetonate, gallium nitrate and their hydrates; preferably, the solvent of the precursor solution is deionized water and / or an organic solvent; more preferably, the organic solvent includes one or more of ethanol, isopropanol, and 2-methoxyethanol.

3. The method according to claim 1, characterized in that In S1, in the precursor solution, the molar ratio of magnesium to gallium is 2-20:80-98, preferably 8-12:88-92; preferably, the concentration of magnesium is 0.04-0.06 mol / L.

4. The method according to claim 1, characterized in that: In S2, an epitaxial layer is prepared on the substrate by spin coating; preferably, when preparing the epitaxial layer, after dropping a precursor solution in the center of the substrate, the substrate is first controlled to spin at a rate of 800-1200rpm for 5-15s, and then the substrate is controlled to spin at a rate of 2500-3500rpm for 20-40s to obtain a substrate with an epitaxial layer; more preferably, the amount of the precursor solution added is 30-80μL; preferably, spin coating is performed by a desktop coating machine; preferably, the material of the substrate is sapphire.

5. The method according to any one of claims 1 to 3, characterized in that: In S3, the annealing temperature is 175-225°C, preferably 180-220°C.

6. The method according to any one of claims 1 to 3, characterized in that: In S3, the annealing time is 10-50 min, preferably 15-45 min, and more preferably 20-40 min.

7. The method according to any one of claims 1 to 3, characterized in that: In S4, S2-S3 are repeated sequentially 2-8 times, preferably 3-7 times, and more preferably 4-6 times.

8. The method according to any one of claims 1 to 3, characterized in that: In S5, the annealing temperature is 575-725°C, preferably 600-700°C, and more preferably 625-675°C.

9. The method according to any one of claims 1 to 3, characterized in that: In S5, the annealing time is 1-3 h, preferably 1.25-2.75 h, and more preferably 1.5-2.5 h.

10. A method for preparing a Mg-doped gallium oxide solar-blind ultraviolet photodetector, characterized in that: The steps include: (1) Preparing a Mg-doped gallium oxide thin film on a substrate by the method according to any one of claims 1 to 9; preferably, the substrate is made of one of sapphire, gallium nitride and gallium oxide; (2) Preparing a gold electrode on the Mg-doped gallium oxide film obtained in step (1) to obtain a Mg-doped gallium oxide solar-blind ultraviolet photodetector.

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