Tin-doped amorphous gallium oxide film and preparation method thereof

Abstract

The invention relates to the technical field of metal oxide thin film preparation, in particular to a tin-doped amorphous gallium oxide thin film and a preparation method thereof. Comprising the following steps: uniformly mixing nanoscale SnO2 powder with common SnO2 powder, adding the mixture into an infrared ceramic mold, pressing the mixture into a pre-sintered target block, sintering the pre-sintered target block in an oxygen atmosphere, and cooling the pre-sintered target block to obtain a SnO2 dopant ceramic target material; putting the cleaned substrate and the target seat loaded with the Ga2O3 target material into a sputtering chamber; n SnO2 dopant ceramic target materials are stacked on the annular sputtering area of the Ga2O3 target material at equal intervals to form annular arrangement and distribution, and vacuumizing is carried out; wherein N > = 1; and introducing inert gas at room temperature, and carrying out magnetron sputtering, so that the sputtering target material is deposited on the surface of the substrate. The method has the advantages of flexible doping concentration regulation and high preparation efficiency; the film is good in quality and low in defect concentration; the process is simple and low in cost; and the performance optimization of the device can be realized.

Description

Technical Field

[0001] This invention relates to the field of metal oxide thin film preparation technology, and in particular to a tin-doped amorphous gallium oxide thin film and its preparation method. Background Technology

[0002] Amorphous gallium oxide (a-Ga2O3) thin films exhibit great application potential in optoelectronic devices and other fields due to their excellent physicochemical properties. Doping can effectively control their electrical properties, which is one of the key technologies for realizing device applications.

[0003] Magnetron sputtering has become an ideal method for preparing doped thin films due to its advantages such as low cost, high yield, and good controllability. Currently, there are two main processes for preparing doped a-Ga₂O₃ thin films using magnetron sputtering: 1. Co-sputtering: This method uses a pre-fabricated composite target with a fixed doping concentration for sputtering. The advantages of this method are process stability and the ease of obtaining thin films with uniform quality. However, its disadvantages are also significant: First, it cannot flexibly adjust the doping concentration of the film; each concentration requires a custom-made target, resulting in high R&D and production costs. Second, different sputtering process parameters need to be explored for different doping concentrations of the target, leading to low production efficiency.

[0004] 2. Metal Particle Stacking Method: Metal particles (dopant sources) are stacked on the surface of a conventional Ga2O3 target, followed by sputtering. While this method allows for flexible adjustment of the doping concentration, it suffers from serious drawbacks: the metal particles are difficult to completely ionize during sputtering, leading to some metal atoms directly entering the thin film, forming impurities, causing lattice distortion and numerous defects. Although introducing oxygen and heating can repair these defects to some extent, this significantly increases equipment complexity and energy costs, places extremely high demands on precise gas flow control, and reduces sputtering yield, affecting production efficiency and film stability. Furthermore, multi-target co-sputtering methods typically require high-temperature annealing processes, which can cause amorphous gallium oxide to crystallize, making it unsuitable for preparing high-performance amorphous doped thin films.

[0005] Therefore, how to flexibly, efficiently, and cost-effectively prepare high-quality amorphous gallium oxide thin films with different doping concentrations is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a tin-doped amorphous gallium oxide thin film and its preparation method.

[0007] The primary objective of this invention is to provide a method for preparing tin-doped amorphous gallium oxide thin films, specifically comprising the following steps: S1. Mix nano-sized SnO2 powder with ordinary SnO2 powder, add it into an infrared ceramic mold and press it into a pre-fired target block, then sinter and cool it under an oxygen atmosphere to obtain SnO2 doped ceramic target material. S2. Clean the substrate; place the cleaned substrate and the target holder loaded with Ga2O3 target material into the sputtering chamber; S3. Place the Ga2O3 target at the center of the sputtering chamber. Based on the required doping concentration, stack N SnO2 doped ceramic targets at equal intervals on the annular sputtering region of the Ga2O3 target to form a ring-shaped arrangement. Evacuate the chamber. Wherein, N≥1. S4. At room temperature, an inert gas is introduced and the sputtering pressure is adjusted to 3~5 Pa; magnetron sputtering is performed to deposit the sputtering target on the substrate surface to obtain a tin-doped amorphous gallium oxide thin film.

[0008] Preferably, step S1 includes the following sub-steps: S101. Mix nano-sized SnO2 powder with ordinary SnO2 powder of 250~350 mesh at a mass ratio of 1:8~10, and add a small amount of alcohol to grind and mix thoroughly. S102. Add the mixed powder to the infrared ceramic mold, apply a pressure of 8~10 MPa, hold the pressure for 0.5~2 minutes and then demold to obtain a pre-fired target block with a thickness of 1~2 mm; S103. The pre-fired target block is sintered in an oxygen atmosphere at 1000~1200℃ for 1.5~2.5 hours to make it completely dense and ceramicized. After cooling, the SnO2 doped ceramic target material is obtained.

[0009] Preferably, the particle diameter of the nano-sized SnO2 powder is less than 100 nm; the mass ratio of the nano-sized SnO2 powder to the ordinary SnO2 powder is 1:9.

[0010] Preferably, the pressure holding time in step S102 is 1 minute.

[0011] Preferably, the sintering in step S103 is carried out in a tube furnace at a sintering temperature of 1100°C for 2 hours.

[0012] Preferably, the particle diameter of the nano-sized SnO2 powder is less than 100 nm; the substrate is selected as an Al2O3 (0001) double-polished sapphire substrate.

[0013] Preferably, N=3 in step S3.

[0014] Preferably, the inert gas in step S4 is pure argon; the sputtering pressure is adjusted to 4 Pa; the magnetron sputtering power is 100~150W, and the sputtering time is 20~40 minutes.

[0015] Preferably, the magnetron sputtering power is 120W; the thickness of the tin-doped amorphous gallium oxide film is 300~350nm.

[0016] The second objective of this invention is to provide a tin-doped amorphous gallium oxide thin film, prepared using a method for preparing a tin-doped amorphous gallium oxide thin film.

[0017] Compared with the prior art, the present invention can achieve the following beneficial effects: (1) Flexible doping concentration control and high preparation efficiency: By simply increasing or decreasing the number of doped ceramic targets stacked on the main target, the doping concentration in the film can be quickly and conveniently controlled without replacing the entire main target, which greatly improves the research and development and production efficiency of preparing films with different doping concentrations.

[0018] (2) High film quality and low defect concentration: This invention uses an oxide ceramic target (such as SnO2) doped with elements as the doping source. During sputtering, this target can not only ionize dopant ions (such as SnO2) but also... 4+ It can also release oxygen ions simultaneously; these oxygen ions can effectively replenish the oxygen lost due to sputtering, thereby significantly reducing oxygen vacancy defects in the thin film and avoiding lattice distortion caused by direct doping of metal atoms. Experiments show that by optimizing the doping concentration, the oxygen vacancy concentration can be reduced from over 36% to less than 10%.

[0019] (3) Simple process and low cost: The preparation method of the present invention does not require additional oxygen to be introduced during the sputtering process, which simplifies process control and reduces the requirements for gas flow control equipment. At the same time, since high-quality amorphous thin films can be obtained without high-temperature annealing, energy consumption is also reduced, making the entire preparation process extremely low in terms of equipment and energy requirements, resulting in a significant cost advantage.

[0020] (4) Device performance optimization can be achieved: The preparation method of the present invention can be used to easily carry out gradient doping experiments and accurately find the "optimal process window" with the fewest defects (such as oxygen vacancies) and the best electrical performance (such as carrier concentration), providing a reliable basis for the preparation of high-performance devices. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the arrangement and distribution of SnO2 doped ceramic target on the annular sputtering region of Ga2O3 target according to an embodiment of the present invention.

[0022] Figure 2 This is a schematic diagram of the principle of stacked target radio frequency magnetron sputtering according to an embodiment of the present invention.

[0023] Figure 3 This is a statistical analysis result graph of tin with different doping concentrations provided in an embodiment of the present invention.

[0024] Figure 4 These are XPS analysis spectra of tin-doped amorphous gallium oxide (Sn:a-Ga2O3) thin films with different doping concentrations provided according to embodiments of the present invention; wherein: (a) is the full XPS spectrum of the sample; and (b) is the three-dimensional spectrum of the Sn 3d peak.

[0025] Figure 5 The figures show the chemical state and defect analysis results of tin-doped amorphous gallium oxide thin films with different doping concentrations according to embodiments of the present invention; wherein: (a) is a fine spectrum of the Sn 3d peak of different samples; (b) is a fine spectrum of the O 1s peak of different samples; (c) is a fine spectrum of the Sn 3d peak of different samples. 4+ Ion ratio and lattice oxygen O L A statistical chart showing the percentages.

[0026] Figure 6 This is a graph showing the relationship between carrier concentration, resistivity and Sn doping concentration of a tin-doped amorphous gallium oxide thin film according to an embodiment of the present invention.

[0027] Figure label: 1. SnO2-doped ceramic target; 2. Ga2O3 target material; 3. Annular sputtering area; 4. Substrate; 5. Magnetic field; 6. Copper target; 7. Cooling system. Detailed Implementation

[0028] In the following description, embodiments of the invention will be described with reference to the accompanying drawings. In the description below, the same modules are denoted by the same reference numerals. Where the same reference numerals are used, their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0030] This invention provides a method for preparing tin-doped amorphous gallium oxide (Sn:a-Ga2O3) thin films using stacked target radio frequency magnetron sputtering, specifically including the following steps: S1. Preparation of SnO2-doped ceramic targets (SnO2 small targets): Nanoscale SnO2 powder is mixed with ordinary SnO2 powder, added to an infrared ceramic mold and pressed into a pre-sintered target block, then sintered and cooled under an oxygen atmosphere to obtain SnO2-doped ceramic targets; specifically including: S101. Mix nano-sized SnO2 powder with ordinary SnO2 powder of 250~350 mesh at a mass ratio of 1:8~10, and add a small amount of alcohol to grind and mix thoroughly. Preferably, the particle diameter of the nano-sized SnO2 powder is less than 100 nm; the mass ratio of nano-sized SnO2 powder to ordinary SnO2 powder is 1:9. S102. Add the mixed powder to the infrared ceramic mold, apply a pressure of 8~10 MPa, hold the pressure for 0.5~2 minutes and then demold to obtain a pre-fired target block with a thickness of 1~2 mm; Preferably, 0.35g of mixed powder is weighed; the size of the infrared ceramic mold is determined according to the size of the effective sputtering area of ​​the main target material, and in a specific embodiment, the radius of the infrared ceramic mold is 4 mm; the holding time is 1 minute; and the thickness of the pre-fired target block is 1.5 mm. S103. The pre-sintered target block is sintered in an oxygen atmosphere at 1000~1200℃ for 1.5~2.5 hours to make it completely dense and ceramicized. After cooling, SnO2 doped ceramic target material is obtained. Preferably, sintering is carried out in a tube furnace at a temperature of 1100°C for 2 hours.

[0031] S2. Clean the substrate using standard cleaning processes, and place the cleaned substrate and the target holder loaded with Ga2O3 target material into the sputtering chamber; Specifically, an Al2O3 (0001) double-polished sapphire substrate was selected; S3. Place the Ga2O3 target at the center of the sputtering chamber as the main target; according to the required doping concentration, stack N SnO2 doped ceramic targets at equal intervals on the annular sputtering region of the Ga2O3 target to form a ring arrangement to obtain the sputtering target; evacuate; where N≥1; Specifically, the vacuum level in the sputtering chamber was evacuated to 5 × 10⁻⁶. -4 Pa; S4. At room temperature, pure argon (Ar) gas is introduced as the sputtering atmosphere, and the sputtering pressure is adjusted to 3~5 Pa; turn on the RF power supply to perform target stacking magnetron sputtering, so that the sputtering target material is deposited on the substrate surface to obtain a tin-doped amorphous gallium oxide thin film. Preferably, the magnetron sputtering power is 100~150W, the sputtering time is 20~40 minutes, and the thickness of the tin-doped amorphous gallium oxide film is 300~350nm; In a specific embodiment, the parameters for magnetron sputtering are: sputtering pressure of 4 Pa, sputtering power of 120 W, and sputtering time of 30 minutes.

[0032] Example 1 See Figures 1-2This embodiment provides a method for preparing tin-doped amorphous gallium oxide thin films (Sn:a-Ga2O3) using stacked target radio frequency magnetron sputtering, specifically including the following steps: S1. Preparation of SnO2 doped ceramic target 1 (SnO2 small target): S101. Mix nano-sized SnO2 powder with a particle diameter of less than 100 nm with ordinary SnO2 powder of 300 mesh at a mass ratio of 1:9, and add a small amount of alcohol to grind and mix thoroughly. S102. Weigh 0.35g of the mixed powder and add it to an infrared ceramic mold with a radius of 4mm. Apply a pressure of 8~10 MPa, hold the pressure for 1 minute, and then demold to obtain a pre-fired target block with a thickness of about 1.5mm. S103. The pre-sintered target block is sintered in an oxygen atmosphere at 1100°C for 2 hours to make it completely dense and ceramicized. After cooling, SnO2 doped ceramic target material 1 is obtained.

[0033] S2. Clean the substrate 4 using standard cleaning processes, and place the cleaned substrate and the target holder loaded with Ga2O3 target 2 into the sputtering chamber; Substrate 4 is selected as Al2O3 (0001) double-polished sapphire substrate.

[0034] S3. Place the Ga2O3 target 2 at the center of the sputtering chamber as the main target; stack a SnO2-doped ceramic target 1 on the annular sputtering region 3 of the Ga2O3 target 2 to obtain the sputtering target; evacuate the vacuum to 5 × 10⁻⁶. -4 Pa; S4. At room temperature, pure argon (Ar) gas is introduced as the sputtering atmosphere, and the sputtering pressure is adjusted to 4 Pa; the RF power supply is turned on to perform magnetron sputtering, so that the sputtering target material is deposited on the substrate surface to obtain a tin-doped amorphous gallium oxide film with a thickness of 300~350 nm (doping concentration 1.96%); the magnetron sputtering parameters are: sputtering pressure of 4 Pa, sputtering power of 120 W, and sputtering time of 30 minutes.

[0035] according to Figure 2 The principle of stacked target magnetron sputtering is shown. The specific sputtering process is as follows: During the sputtering process, Ar gas is ionized to form Ar⁺ ions, which are accelerated towards the target material under the action of electric field E. The Ar⁺ ions bombard the target surface, causing the target atoms or molecules to be sputtered out and move towards the substrate 4, eventually forming a thin film on the substrate. Figure 2 The presence of magnetic field 5 is also shown, which helps to confine electron movement and improve sputtering efficiency; there is a cooling system 7 below the copper target 6 (cathode) to maintain the temperature of the target material during the sputtering process; this stacking method and sputtering process can be used to prepare tin-doped amorphous gallium oxide (Sn:a-Ga2O3) thin films with different doping concentrations.

[0036] Example 2 This embodiment provides a method for preparing tin-doped amorphous gallium oxide thin films based on stacked target radio frequency magnetron sputtering; wherein, in step S3, two SnO2 doped ceramic targets 1 are stacked at equal intervals on the annular sputtering region 3 of Ga2O3 target 2 to form an annular arrangement to obtain sputtering targets; the final tin-doped amorphous gallium oxide thin film has a doping concentration of 3.7%.

[0037] Example 3 This embodiment provides a method for preparing tin-doped amorphous gallium oxide thin films based on radio frequency magnetron sputtering using stacked targets; wherein, in step S3, three SnO2-doped ceramic targets 1 are stacked at equal intervals on the annular sputtering region 3 of Ga2O3 target 2 to form an annular arrangement to obtain sputtering targets; the final tin-doped amorphous gallium oxide thin film has a doping concentration of 5.45%.

[0038] Example 4 This embodiment provides a method for preparing tin-doped amorphous gallium oxide thin films based on radio frequency magnetron sputtering using stacked targets; wherein, in step S3, four SnO2-doped ceramic targets 1 are stacked at equal intervals on the annular sputtering region 3 of Ga2O3 target 2 to form an annular arrangement and obtain sputtering targets; the final tin-doped amorphous gallium oxide thin film has a doping concentration of 8.54%.

[0039] Example 5 This embodiment provides a method for preparing tin-doped amorphous gallium oxide thin films based on radio frequency magnetron sputtering using stacked targets; wherein, in step S3, five SnO2-doped ceramic targets 1 are stacked at equal intervals on the annular sputtering region 3 of Ga2O3 target 2 to form an annular arrangement to obtain sputtering targets; the final tin-doped amorphous gallium oxide thin film has a doping concentration of 12.54%.

[0040] The tin-doped amorphous gallium oxide thin films prepared in Examples 1-5 were labeled as samples D1, D2, D3, D4, and D5, respectively. Performance tests were performed on samples D1-D5, and the results are as follows: Figures 3-6 As shown.

[0041] Figure 3 For the doping concentration analysis results: By changing the amount of SnO2 target material, a series of thin films with Sn atomic concentrations (Sn / (Sn+Ga)) of 1.96% (D1), 3.70% (D2), 5.45% (D3), 8.54% (D4), and 12.54% (D5) were successfully prepared. The results show that by changing the amount of SnO2 doped ceramic target material, the Sn doping concentration in the thin film can be conveniently and precisely controlled.

[0042] Figure 4 XPS analysis spectra of tin-doped amorphous gallium oxide films (samples D1~D5) with different doping concentrations are shown.

[0043] Figure 5 The results show the chemical state and defect analysis of samples D1 to D5. The results indicate that: Sample D1 (1 target, 1.96% Sn): Sn 4+ The proportion of ions was only 43.89%, while the oxygen vacancy concentration was as high as 36.04%. Sample D2 (2 targets, 3.70% Sn): With the increase of SnO2 source, the amount of O ions provided increases, and the oxygen vacancy concentration decreases to 29.54%. 4+ Its share increased to 56.41%; Sample D3 (3 targets, 5.45% Sn): At this point, the optimal state is reached. The O ions provided by SnO2 effectively compensate for the oxygen vacancies, causing its concentration to drop sharply to 8.66%; simultaneously, Sn... 4+ The proportion reached a peak of 91.34%, indicating that Sn achieved the most efficient substitutional doping under these conditions; Sample D4 (4 targets, 8.54% Sn): With further increase in doping concentration, the lattice distortion effect caused by the difference in Sn and Ga ion radii began to appear, and the oxygen vacancy concentration rebounded to 17.1%. 4+ The proportion dropped to 78.83%; Sample D5 (5 targets, 12.54% Sn): The lattice distortion effect caused by high doping concentration is more obvious, with the oxygen vacancy concentration rising to 19.08% and Sn 4+ The percentage dropped to 76.94%. This indicates that at a fixed power of 120 W, the excessively high dopant flux exceeded the optimal process window.

[0044] Electrical performance analysis results Figure 6 . Figure 6 The trend of carrier concentration in the thin film with doping concentration is in high agreement with the defect analysis results. From D1 to D3, with the improvement of Sn effective doping efficiency and defect repair, the carrier concentration continues to rise, reaching a peak at D3 (5.45% Sn) (approximately 2.7 × 10⁻⁶). 17 cm -3 Subsequently, as the defect concentration in D4 and D5 increased, the carrier concentration began to decrease. This clearly demonstrates that this method can effectively control the electrical properties by adjusting the doping concentration and optimizing the film quality.

[0045] In summary, the stacked target magnetron sputtering method proposed in this invention can conveniently and quickly prepare amorphous gallium oxide thin films with different doping concentrations. Under suitable process parameters (such as a doping concentration of 5.45% corresponding to a sputtering power of 120 W), it can effectively reduce the defect concentration of the thin film and improve its electrical properties, thus having extremely high practical value and application prospects.

[0046] 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 this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0047] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for preparing a tin-doped amorphous gallium oxide thin film, characterized in that: Specifically, the steps include the following: S1. Mix nano-sized SnO2 powder with ordinary SnO2 powder, add it into an infrared ceramic mold and press it into a pre-fired target block, then sinter and cool it under an oxygen atmosphere to obtain SnO2 doped ceramic target material. S2. Clean the substrate; place the cleaned substrate and the target holder loaded with Ga2O3 target material into the sputtering chamber; S3. Place the Ga2O3 target at the center of the sputtering chamber. Based on the required doping concentration, stack N SnO2 doped ceramic targets at equal intervals on the annular sputtering region of the Ga2O3 target to form a ring-shaped arrangement. Evacuate the chamber. Wherein, N≥1. S4. At room temperature, an inert gas is introduced and the sputtering pressure is adjusted to 3~5 Pa; magnetron sputtering is performed to deposit the sputtering target on the substrate surface to obtain a tin-doped amorphous gallium oxide thin film.

2. The method for preparing a tin-doped amorphous gallium oxide thin film according to claim 1, characterized in that: Step S1 includes the following sub-steps: S101. Mix nano-sized SnO2 powder with ordinary SnO2 powder of 250~350 mesh at a mass ratio of 1:8~10, and add a small amount of alcohol to grind and mix thoroughly. S102. Add the mixed powder to the infrared ceramic mold, apply a pressure of 8~10 MPa, hold the pressure for 0.5~2 minutes and then demold to obtain a pre-fired target block with a thickness of 1~2 mm; S103. The pre-fired target block is sintered in an oxygen atmosphere at 1000~1200℃ for 1.5~2.5 hours to make it completely dense and ceramicized. After cooling, the SnO2 doped ceramic target material is obtained.

3. The method for preparing a tin-doped amorphous gallium oxide thin film according to claim 2, characterized in that: The particle diameter of the nano-sized SnO2 powder is less than 100 nm; the mass ratio of the nano-sized SnO2 powder to the ordinary SnO2 powder is 1:

9.

4. The method for preparing a tin-doped amorphous gallium oxide thin film according to claim 2, characterized in that: The pressure holding time in step S102 is 1 minute.

5. The method for preparing a tin-doped amorphous gallium oxide thin film according to claim 2, characterized in that: The sintering in step S103 is carried out in a tube furnace at a temperature of 1100°C for 2 hours.

6. The method for preparing a tin-doped amorphous gallium oxide thin film according to claim 1, characterized in that: The particle diameter of the nano-sized SnO2 powder is less than 100 nm; the substrate is selected as an Al2O3 (0001) double-polished sapphire substrate.

7. The method for preparing a tin-doped amorphous gallium oxide thin film according to claim 1, characterized in that: In step S3, N=3.

8. The method for preparing a tin-doped amorphous gallium oxide thin film according to claim 1, characterized in that: The inert gas in step S4 is pure argon; the sputtering pressure is adjusted to 4 Pa; the magnetron sputtering power is 100~150W, and the sputtering time is 20~40 minutes.

9. The method for preparing a tin-doped amorphous gallium oxide thin film according to claim 8, characterized in that: The magnetron sputtering power is 120W; the thickness of the tin-doped amorphous gallium oxide film is 300~350nm.

10. A tin-doped amorphous gallium oxide thin film, characterized in that: The tin-doped amorphous gallium oxide thin film was prepared using the method described in claim 1.

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