Method for preparing indium nitride and gallium indium nitride thin film by hot-wire assisted atomic layer deposition

Abstract

This invention discloses a method for preparing indium nitride and gallium nitride indium thin films by hot-wire assisted atomic layer deposition (ATD). The steps include: alternately introducing In(CH3)3 or Ga(C2H5)3 and N2 / NH3 according to the timing sequence of ATD deposition of indium nitride or gallium nitride thin films; adjusting the surface temperature of the hot wire to 600-1300℃; utilizing a high-temperature monolayer hot wire array or a multilayer staggered hot wire array to decompose the N2 / NH3 mixture to generate nitrogen-active groups that react with the thermal decomposition products of In(CH3)3 or Ga(C2H5)3 on the substrate surface to prepare monolayer indium nitride or monolayer gallium nitride thin films; achieving alternating deposition of indium nitride and gallium nitride thin films by changing the number of cycles and the order of deposition; and annealing the deposited multilayer films to obtain In films with different indium contents. x Ga 1‑x Indium (InN) semiconductor thin films. This invention utilizes atomic layer deposition (ALD) and high-temperature hot-filament decomposition (HTFD) techniques to control the indium content in gallium nitride (GaN) thin films through alternating deposition. After annealing, In films with adjustable bandgap can be obtained. x Ga 1‑x N-type semiconductor thin films.

Description

Technical Field

[0001] This application belongs to the field of thin film preparation technology, and particularly relates to a method for preparing indium nitride and gallium indium nitride thin films by hot filament-assisted atomic layer deposition. Background Technology

[0002] Currently, the most common methods for preparing indium nitride (InN) and indium gallium nitride (InGaN) thin films include molecular beam epitaxy (MBE), metal-organic chemical vapor deposition (MOCVD), and atomic layer deposition (ALD). Atomic layer deposition, due to its self-limiting growth characteristics, has become one of the important methods for producing high-quality thin films. For ALD of indium nitride and indium gallium nitride thin films, TMIn (Trimethylindium, chemical formula In(CH3)3) is generally used as the indium source, TEGa (Triethylgallium, chemical formula Ga(C2H5)3) is used as the gallium source, and N2, N2 / NH3 mixtures, or N2 / H2 mixtures from plasma are used as the nitrogen source.

[0003] However, using N2 plasma as the nitrogen source results in a low concentration of nitrogen-active groups, even under high-power plasma conditions, due to the high N / N bond energy in N2, which makes dissociation difficult. Therefore, this method primarily produces indium nitride (INB) films rich in nitrogen. Using N2 / NH3 and N2 / H2 mixtures as nitrogen sources can increase the nitrogen content in INB, but the generation of nitrogen-active groups from these mixtures is highly random, with significant variations in concentration and energy. While increasing plasma power can improve the concentration of nitrogen-active groups, INB and gallium indium nitride films deposited under high-power plasma are susceptible to plasma damage, resulting in numerous pinholes on the film surface and deep within the film. These defects are detrimental to the growth of high-quality INB and gallium indium nitride films.

[0004] Therefore, existing thin film deposition processes face a contradiction between "high-quality thin films" and "high-power plasma damage," and there is an urgent need to develop a method to prepare indium nitride and gallium indium nitride thin films without damage. Summary of the Invention

[0005] The purpose of this application is to provide a method for preparing indium nitride and indium gallium nitride thin films by hot-wire assisted atomic layer deposition (ATLD). This method utilizes the zero-plasma advantage of high-temperature hot-wire N2 / NH3 pyrolysis to avoid plasma damage. Furthermore, based on hot-wire assisted ALD deposition of indium nitride thin films, the introduction of a triethylgallium (TEGa) source and annealing treatment overcomes the limitation of only being able to prepare single-layer InN thin films, enabling the preparation of non-destructive, high-quality InN films with adjustable indium content. x Ga 1-x N thin film.

[0006] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows: This application provides a method for preparing indium nitride and indium gallium nitride thin films by hot-wire assisted atomic layer deposition, including the following steps: (1) Substrate pretreatment: If the substrate is selected as single crystal ZnO(004), that is, the substrate is selected as single crystal ZnO with crystal orientation of (004), use acetone to sonicate for 10 min to remove organic matter on the substrate surface, then use ethanol and deionized water to sonicate for 10 min in sequence, take it out and blow dry the substrate with high-purity nitrogen gas, and finally use Ar plasma to etch the surface to improve the cleanliness of the substrate surface. If the substrate is selected as CZ-Si(100), that is, the substrate is selected as Czochralski single crystal silicon CZ-Si with crystal plane orientation of (100). The oxide on the surface is removed by HF beforehand, and then the single crystal ZnO(004) is cleaned according to the cleaning method. Finally, a high-quality ZnO film is deposited on the single crystal silicon. If the substrate is selected as single crystal Al2O3(0001), that is, the substrate is selected as single crystal Al2O3 with crystal plane orientation of (0001) (also known as single crystal sapphire with c plane orientation). It is soaked in aqua regia at 80°C to remove dust and oxides on the substrate surface. Then it is cleaned according to the single crystal ZnO(004) cleaning method. Finally, a high-quality GaN film is deposited on the sapphire. (2) InN thin film deposition: Adjust the pulse duty cycle or power output of the hot wire heating power supply to make the surface temperature of the hot wire reach 600-1300℃. Using In(CH3)3 as the indium source and N2 / NH3 mixed gas from the high-temperature hot wire decomposition as the nitrogen source, In(CH3)3 and N2 / NH3 mixed gas are alternately introduced according to the atomic layer deposition sequence of indium nitride thin film. N2 / NH3 is decomposed into nitrogen active groups through a high-temperature single-layer hot wire array or a multi-layer staggered array, and a single-layer InN thin film is prepared on the substrate; (3) GaN thin film deposition: Adjust the pulse duty cycle or power output of the hot wire heating power supply to make the surface temperature of the hot wire reach 600-1300℃. Using Ga(C2H5)3 as gallium source and N2 / NH3 mixed gas from high-temperature hot wire decomposition as nitrogen source, Ga(C2H5)3 and N2 / NH3 mixed gas are alternately introduced according to the atomic layer deposition sequence of gallium nitride thin film. N2 / NH3 is decomposed to produce nitrogen active groups through high-temperature single-layer hot wire array or multi-layer staggered array to prepare single-layer GaN thin film; (4) In x Ga 1-xInN thin film deposition: Repeat steps (2) and (3) above, and achieve alternating deposition of InN and GaN by changing the number of cycles for depositing InN and GaN thin films to obtain InN / GaN / InN multilayer films. Annealing is then used to obtain InN films with different indium contents. x Ga 1-x N-type semiconductor thin films.

[0007] Optionally, in steps (2) and (3), the surface temperature of the hot wire is changed by adjusting the pulse duty cycle or power output of the hot wire heating power supply of a single-layer hot wire array or a multi-layer staggered array, so as to control the thermal decomposition efficiency of N2 / NH3.

[0008] Optionally, in step (4), In with different indium contents is prepared. x Ga 1-x The specific processes for N-type semiconductor thin films include: Reduce the vacuum level in the deposition chamber to 1×10 -3 Below Pa, the substrate temperature is heated to 150-450℃, and argon gas is introduced to maintain the vacuum degree of the deposition chamber at 0.1-10.0 Pa. The duty cycle or power output of the hot wire heating power supply is adjusted to make the surface temperature of the hot wire 600-1300℃. In(CH3)3 and N2 / NH3 are alternately introduced according to the atomic layer deposition sequence of indium nitride thin film. The N2 / NH3 is decomposed by the high-temperature hot wire to release nitrogen active groups, which react with the thermal decomposition products of In(CH3)3 on the substrate surface. After 20-80 cycles, an InN thin film of 2-8 nm is prepared. Ga(C2H5)3 and N2 / NH3 are alternately introduced according to the atomic layer deposition sequence of gallium nitride thin film. Nitrogen-active groups from N2 / NH3 are pyrolyzed using a high-temperature hot filament and react with the thermal decomposition products of Ga(C2H5)3 on the substrate surface. After 20-100 cycles, a 2-10 nm GaN thin film is prepared. In(CH3)3 and N2 / NH3 are alternately introduced according to the atomic layer deposition sequence of indium nitride thin films, and after 20-80 cycles, an indium thin film of 2-8 nm is prepared, thus obtaining an inN / GaN / InN multilayer film. The deposited multilayer films are then annealed to obtain indium films with different indium contents. x Ga 1-x N thin film.

[0009] Optionally, in step (4): by changing the number of cycles and alternation order of depositing InN and GaN, multilayer composite films of different thicknesses composed of alternating InN and GaN deposition are prepared, and the bottom layer and top layer of the multilayer composite film are both InN films.

[0010] Optionally, in step (4): by changing the number of cycles and alternation order of depositing InN and GaN, and through annealing, In with different indium contents can be obtained.x Ga 1-x N-type semiconductor thin films.

[0011] Optionally, the substrate pretreatment may also include the following degassing steps: Place the substrate onto the sample holder in the deposition chamber, and then turn on the dry vacuum pump and molecular pump in sequence to achieve a vacuum level of 1.0 × 10⁻⁶ in the deposition chamber. -3 Below Pa, heat the substrate to 150°C and degas the substrate for half an hour.

[0012] Compared with the prior art, the beneficial effects of the embodiments of this application are: The method for preparing indium nitride and gallium indium nitride thin films by hot-wire assisted atomic layer deposition provided in this application uses TMIn as the indium source, TEGa as the gallium source, and N2 / NH3 from high-temperature hot-wire decomposition as the nitrogen source. By changing the number of atomic layer deposition cycles for InN and GaN, the hot-wire surface temperature of a single-layer hot-wire array or a multi-layer staggered array, and the spacing between the staggered arrays, multilayer composite thin films of different thicknesses composed of alternating InN and GaN deposition are prepared. The bottom and top layers of the multilayer composite thin films are both InN films. After deposition, the multilayer composite thin films are annealed. x Ga 1-x The quality of N thin films can be significantly improved, showing promising application prospects for the development of optoelectronic devices. The hot-filament assisted atomic layer deposition (HFAD) technique used in this invention is zero-plasma, causing zero damage to the deposited film surface, and has significant advantages compared to plasma-derived N2, N2 / NH3 mixtures, and N2 / H2 mixtures. By changing the surface temperature of the single-layer array hot filament, the concentration of nitrogen-active groups in the hot-filament-derived N2 / NH3 mixture can be adjusted. Furthermore, double-layer and multi-layer staggered arrays can be used to further improve the N2 / NH3 pyrolysis efficiency. The advantages of double-layer and multi-layer staggered arrays are more pronounced, specifically including: 1) expanding the N2 / NH3 pyrolysis region, further improving the N2 / NH3 pyrolysis efficiency, effectively suppressing the polymerization of pyrolyzed nitrogen-active groups, and significantly increasing the chemical ratios of In:N, Ga:N, and (In+Ga):N, thereby obtaining high-quality, non-destructive InN, GaN, and In... x Ga 1-x 2) After pyrolysis, nitrogen-active groups can obtain higher energy when passing through the high-temperature region between the double-layer interlaced array and the multi-layer interlaced array, which is conducive to the migration and chemical bonding of nitrogen-active groups on the substrate surface. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the deposition chamber structure and the high-temperature single-layer array hot filament nitrogen / ammonia mixed gas pyrolysis in this invention.

[0015] Figure 2 This is a schematic diagram of the deposition chamber structure and the high-temperature double-layer staggered array of hot filaments for nitrogen / ammonia gas pyrolysis in this invention.

[0016] Figure 3 This is a schematic diagram of the deposition chamber structure and the high-temperature multilayer staggered array hot filament nitrogen / ammonia gas pyrolysis in this invention.

[0017] Figure 4 The timing diagram of atomic layer deposition of InN thin films is shown.

[0018] Figure 5 The timing diagram of atomic layer deposition of GaN thin films is shown. Detailed Implementation

[0019] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0020] To illustrate the technical solution described in this application, specific embodiments are provided below.

[0021] Please see Figures 1 to 5 As shown, embodiments of this application provide a method for preparing indium nitride and indium gallium nitride thin films using hot-wire assisted atomic layer deposition (ITD). The method employs ITD techniques and hot-wire assisted N2 / NH3 splitting technology using single-layer arrays and multi-layer staggered arrays to deposit InN, GaN, and InN on a pretreated substrate. x Ga 1-x N thin film, comprising the following steps: (1) Substrate pretreatment: If a single-crystal ZnO(004) substrate is selected, the substrate is pretreated by cleaning and degassing.

[0022] For example, the pretreatment includes: placing the cleaned, dried, and surface-etched single-crystal ZnO(004) substrate onto the sample holder in the deposition chamber, and sequentially turning on the vacuum dry pump and the molecular pump to achieve a vacuum level of 1.0 × 10⁻⁶ in the deposition chamber. -3Below Pa, heat the single crystal ZnO substrate to 150°C and degas the single crystal ZnO substrate for half an hour.

[0023] If the substrate is selected as CZ-Si(100) or single crystal Al2O3(0001), the substrate is pretreated by cleaning and degassing.

[0024] For example, the pretreatment includes: placing a CZ-Si(100) substrate with a ZnO thin film or a single-crystal Al2O3(0001) substrate with a GaN thin film onto the sample holder in the deposition chamber, and sequentially turning on the vacuum dry pump and the molecular pump to achieve a vacuum level of 1.0 × 10⁻⁶ in the deposition chamber. -3 Heat a single-crystal silicon or sapphire substrate to 150°C below Pa and degas the substrate for half an hour.

[0025] (2) InN thin film deposition: The vacuum level in the deposition chamber is reduced to 1×10 -3 Below Pa, the substrate temperature is heated to 150-450℃, argon gas is introduced to make the vacuum in the deposition chamber 0.1-10.0 Pa, the duty cycle or power output of the hot wire heating power supply is adjusted to make the surface temperature of the hot wire 600-1300℃, and In(CH3)3 and N2 / NH3 are alternately introduced according to the atomic layer deposition sequence of indium nitride thin film (TMIn pulse time = 0.1-1s, TMIn purge time = 2-6s, N2 / NH3 pulse time = 0.3-1s, N2 / NH3 purge time = 5-10s). N2 / NH3 is decomposed by the high temperature hot wire to release nitrogen active groups. After 20-80 cycles, an InN thin film of 2-8nm is prepared.

[0026] (3) GaN thin film deposition: Adjust the duty cycle or power output of the hot wire heating power supply to make the surface temperature of the hot wire 600-1300℃. According to the atomic layer deposition sequence of gallium nitride thin film (TEGa pulse time = 0.1-1s, TEGa purging time = 2-6s, N2 / NH3 pulse time = 0.3-1s, N2 / NH3 purging time = 5-12s), Ga(C2H5)3 and N2 / NH3 are alternately introduced. N2 / NH3 is decomposed by the high temperature hot wire to release nitrogen active groups. After 20-100 cycles, a GaN thin film of 2-10nm is prepared.

[0027] (4) In x Ga 1-xIndium nitride (InN) thin film deposition: Adjust the duty cycle or power output of the hot filament heating power supply to achieve a hot filament surface temperature of 600-1300℃. Alternately introduce In(CH3)3 and N2 / NH3 according to the atomic layer deposition sequence (TMIn pulse time = 0.1-1s, TMIn purge time = 2-6s, N2 / NH3 pulse time = 0.3-1s, N2 / NH3 purge time = 5-10s), and prepare a 2-8nm InN thin film after 20-80 cycles. Then, deposit gallium nitride (GaN) thin films according to the atomic layer deposition sequence (TEGa pulse time = 0.1-1s, TEGa purge time = 2-6s, N2 / NH3 pulse time = 0.3-1s). Ga(C2H5)3 and N2 / NH3 were alternately introduced (N2 / NH3 purge time = 5-10 s) for 20-100 cycles to prepare 2-10 nm GaN thin films. InN and GaN thin films were then deposited alternately using the same method to prepare multilayer composite films of varying thicknesses, consisting of alternating InN and GaN deposits. The bottom and top layers of these multilayer composite films were both InN films. After annealing, InN films with different indium contents were obtained. x Ga 1-x N thin film.

[0028] In the embodiments of this application, alternating deposition of InN and GaN can be achieved by changing the number of cycles of InN and GaN deposition.

[0029] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for preparing indium nitride and indium gallium nitride thin films by hot-wire assisted atomic layer deposition, characterized in that, Includes the following steps: (1) Substrate pretreatment: If the substrate is selected as a single crystal ZnO with a crystal orientation of (004), use acetone to sonicate for 10 min to remove organic matter from the substrate surface, then use ethanol and deionized water to sonicate for 10 min in sequence, take it out and blow it dry with high-purity nitrogen, and finally use Ar plasma to etch the surface to improve the cleanliness of the substrate surface. If the substrate is selected as Czochralski single-crystal silicon CZ-Si with a crystal orientation of (100), the oxide on the surface is removed by HF beforehand, and then it is cleaned according to the single-crystal ZnO (004) cleaning method. Finally, a ZnO thin film is deposited on the single-crystal silicon. If the substrate is selected as a single crystal Al2O3 with a crystal orientation of (0001), it is soaked in aqua regia at 80°C to remove dust and oxides from the substrate surface. Then it is cleaned according to the single crystal ZnO (004) cleaning method. Finally, a GaN thin film is deposited on the single crystal Al2O3. (2) InN thin film deposition: Adjust the pulse duty cycle or power output of the hot wire heating power supply to make the surface temperature of the hot wire reach 600-1300℃. Use In(CH3)3 as the indium source and N2 / NH3 mixed gas from the high-temperature hot wire decomposition as the nitrogen source. In(CH3)3 and N2 / NH3 mixed gas are alternately introduced according to the atomic layer deposition sequence of indium nitride thin film. N2 / NH3 is decomposed into nitrogen active groups through a high-temperature single-layer hot wire array or a multi-layer staggered array to prepare a single-layer InN thin film on the substrate. Among them, TMIn pulse time = 0.1-1s, TMIn purging time = 2-6s, N2 / NH3 pulse time = 0.3-1s, N2 / NH3 purging time = 5-10s; (3) GaN thin film deposition: Adjust the pulse duty cycle or power output of the hot wire heating power supply to make the surface temperature of the hot wire reach 600-1300℃. Use Ga(C2H5)3 as gallium source and N2 / NH3 mixed gas from hot wire decomposition as nitrogen source. Ga(C2H5)3 and N2 / NH3 mixed gas are alternately introduced according to the atomic layer deposition sequence of gallium nitride thin film. N2 / NH3 is decomposed to produce nitrogen active groups through a high-temperature single-layer hot wire array or a multi-layer staggered array to prepare a single-layer GaN thin film. Among them, TEGa pulse time = 0.1-1s, TEGa purging time = 2-6s, N2 / NH3 pulse time = 0.3-1s, N2 / NH3 purging time = 5-12s. (4) In x Ga 1-x InN thin film deposition: Repeat steps (2) and (3) above, and achieve alternating deposition of InN and GaN by changing the number of cycles for depositing InN and GaN thin films to obtain InN / GaN / InN multilayer films. Annealing is then used to obtain InN films with different indium contents. x Ga 1-x N-type semiconductor thin films; In step (3), the surface temperature of the hot wire is changed by adjusting the pulse duty cycle or power output of the hot wire heating power supply in order to control the thermal decomposition efficiency of NH3. In step (4), InN / GaN / InN multilayer films and In films with different indium contents are prepared. x Ga 1-x The specific processes for N thin films include: Reduce the vacuum level in the deposition chamber to 1×10 -3 Below Pa, the substrate temperature is heated to 150-450℃, and argon gas is introduced to maintain the vacuum degree of the deposition chamber at 0.1-10.0 Pa. The duty cycle or power output of the hot wire heating power supply is adjusted to make the surface temperature of the hot wire 600-1300℃. In(CH3)3 and N2 / NH3 are alternately introduced according to the atomic layer deposition sequence of indium nitride thin film. The N2 / NH3 is decomposed by the high-temperature hot wire to release nitrogen active groups, which react with the thermal decomposition products of In(CH3)3 on the substrate surface. After 20-80 cycles, an InN thin film of 2-8 nm is prepared. Ga(C2H5)3 and N2 / NH3 are alternately introduced according to the atomic layer deposition sequence of gallium nitride thin film. Nitrogen-active groups from N2 / NH3 are pyrolyzed using a high-temperature hot filament and react with the thermal decomposition products of Ga(C2H5)3 on the substrate surface. After 20-100 cycles, a 2-10 nm GaN thin film is prepared. In(CH3)3 and N2 / NH3 are alternately introduced according to the atomic layer deposition sequence of indium nitride thin films, and after 20-80 cycles, an indium thin film of 2-8 nm is prepared, thus obtaining an inN / GaN / InN multilayer film. The deposited multilayer films are then annealed to obtain indium films with different indium contents. x Ga 1-x N thin film.

2. The method for preparing indium nitride and indium gallium nitride thin films by hot-wire assisted atomic layer deposition according to claim 1, characterized in that, Substrate pretreatment also includes the following degassing steps: Place the substrate onto the sample holder in the deposition chamber, and then turn on the dry vacuum pump and molecular pump in sequence to achieve a vacuum level of 1.0 × 10⁻⁶ in the deposition chamber. -3 Below Pa, heat the substrate to 150°C and degas the substrate for half an hour.

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