Preparation method of high plasticity cadmium telluride film with super-nanotwin and equiaxed crystal structure

Abstract

The application discloses a preparation method of a high-plasticity cadmium telluride film with super-nanometer twin crystal and equiaxed crystal structures. The cadmium telluride film is prepared by means of magnetron sputtering deposition, and the film with super-nanometer twin crystal and equiaxed crystal structures is prepared by means of work gas pressure regulation and intermittent sputtering at a certain working temperature. The work gas pressure ranges from 1.5 Pa to 3.0 Pa, the working temperature ranges from 25 DEG C to 75 DEG C, the intermittent sputtering method is that sputtering is performed for 20 min to 30 min, sputtering is stopped for 15 min to 30 min as a cycle, and the sputtering is repeated for several cycles so that the total sputtering time is 3 h to 5 h. The cadmium telluride film prepared by the method has an equiaxed crystal average grain size of 5 nm to 10 nm and an average twin crystal layer thickness of 1.2 nm to 2.0 nm, and both are in the order of magnitude of super-nanometer (<10 nm), and the plasticity is increased by 3 to 6 times under the condition that the strength is equivalent to that of a traditional columnar crystal structure.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor materials, specifically relating to a method for preparing cadmium telluride thin films with highly ductile ultra-nanotwins and equiaxed crystal structures. Background Technology

[0002] Cadmium telluride (CdTe) is a high-performance semiconductor material with a band width of 1.50 eV and a good light absorption coefficient (approximately 10). 5 cm -1 Currently, the highest laboratory conversion efficiency of cadmium telluride thin-film batteries is 22%, showing broad application prospects in photovoltaic cells and electronic devices. The main methods for preparing cadmium telluride thin films include magnetron sputtering, electrochemical deposition, wet chemical deposition, vacuum evaporation, and organic solvent methods. Among these, magnetron sputtering offers advantages such as ease of operation, simple process, non-toxicity, and high repeatability, making it suitable for large-scale, controllable production of thin films.

[0003] Related studies have shown that the characteristic dimensions of the microstructure in thin film materials, such as grain size and morphology, have a significant impact on the electrical, optical, and mechanical properties of the films. In the microstructure of materials, nanotwin boundaries are coherent interfaces with low energy, and nanotwin materials typically exhibit good electrical conductivity, thermal stability, and high plasticity. Meanwhile, the morphology and size of grains affect the carrier mobility and phonon scattering properties of semiconductor materials, which are crucial for controlling electrical, optical, and mechanical properties. Research indicates that when the grain morphology changes from columnar crystals with large grain sizes and aspect ratios to equiaxed crystals with nano- or even ultra-nano (<10 nm) sizes, grain boundary movements (such as grain boundary rotation, grain boundary slip, and grain boundary migration) replace dislocation movements as the dominant force in plastic deformation, exhibiting ultra-high plasticity.

[0004] Currently reported cadmium telluride thin films all exhibit columnar crystal structures. While columnar crystal films typically possess high strength, they often demonstrate significant brittleness in flexible device applications. Therefore, developing nanotwinned cadmium telluride thin films with equiaxed crystal structures and effectively controlling their grain morphology and size is crucial for further improving the performance of cadmium telluride thin films and overcoming application bottlenecks. Summary of the Invention

[0005] The present invention aims to provide a method for preparing a highly ductile cadmium telluride thin film with ultra-nano (<10nm) twin and equiaxed crystal structures. By adjusting the working gas pressure and intermittent sputtering at a certain temperature, the grain size and twin layer thickness are controlled to prepare a cadmium telluride thin film with both equiaxed grain size and twin layer thickness less than 10nm. Moreover, the cadmium telluride thin film has good ductility and can meet the application scenarios of flexible devices.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This invention utilizes magnetron sputtering technology, using cadmium telluride alloy as the radio frequency sputtering target and high-purity argon as the working gas. Ionized argon ions bombard the target surface, causing cadmium telluride particles to be sputtered and deposited onto the substrate surface from bottom to top. By controlling the working gas pressure and using an intermittent sputtering method at a specific operating temperature, highly ductile cadmium telluride films with ultra-nanotwin and equiaxed crystal structures are prepared. Specifically, within a working gas pressure range of 1.5 Pa–3.0 Pa and a working temperature range of 25 °C–75 °C, the intermittent sputtering method involves sputtering for 20–30 minutes followed by a 15–30 minute pause, repeating several cycles to achieve a total sputtering time of 3–5 hours. Within this controllable range, cadmium telluride films with an average equiaxed crystal grain size of 5 nm–10 nm, an average aspect ratio of 1.0–1.6, and an average twin layer thickness of 1.2 nm–2.0 nm can be prepared. Specifically, the equiaxed crystal grain size is mainly concentrated in the range of 5nm-10nm, accounting for more than 50% of the total, so the average size is 5nm-10nm; the grain height-to-diameter ratio is mainly concentrated in the range of 1.0-1.6; the twin wafer layer thickness is mainly concentrated in the range of 1.18nm-2.54nm, with an average thickness of 1.2nm-2.0nm.

[0008] The nanotwinned cadmium telluride thin film prepared by the above method has a Cd to Te atomic fraction ratio of 1:1, a film thickness of 1.5μm-2.0μm, an ultimate compressive strength of 1.15GPa-1.35GPa, and an ultimate compressive strain of 15%-30%. Compared with cadmium telluride thin films with columnar crystal structure, its strength is comparable, and its plasticity is improved by 3-6 times.

[0009] This invention provides a more specific method for preparing cadmium telluride thin films with high plasticity, ultra-nanotwins, and equiaxed crystal structures, comprising the following steps:

[0010] (1) Substrate pretreatment: Select single-sided polished monocrystalline silicon as the substrate, perform ultrasonic cleaning, and dry the substrate surface with a hot air blower to make the substrate surface bright and free of impurities. After fixing the substrate on the tray, place it in the sputtering chamber for later use.

[0011] (2) Sputtering preparation: Fix the cadmium telluride alloy target onto the RF power supply, adjust the target-substrate distance to 90mm-100mm, and the sputtering angle to 60°-62°; close the sputtering chamber door, and start the mechanical pump and molecular pump sequentially to evacuate the sputtering chamber to a high vacuum state, with a vacuum level required to be 5×10⁻⁶. -4 Below Pa, high-purity argon gas is introduced as the working gas and a bias voltage is applied to ionize it. The single crystal substrate is cleaned with argon ions for 10-20 minutes.

[0012] (3) Sputtering thin film: According to the present invention, the working temperature and working gas pressure are set, the heating switch is turned on to make the substrate temperature reach the set temperature, and the shut-off valve is opened to introduce argon gas to make the working gas pressure reach the set value; then the substrate baffle, substrate stage rotation switch and radio frequency power switch are turned on in sequence to sputter the thin film. After sputtering for a period of time, the radio frequency power switch is turned off to stop sputtering for a period of time. According to the requirements of the intermittent sputtering method of the present invention, this step is repeated several times to reach the total sputtering time, and a highly ductile cadmium telluride thin film with ultra-nano-twin and equiaxed crystal structure is obtained.

[0013] According to the above scheme, in step (1), the surface of the single crystal silicon is a (100) crystal plane. It is first ultrasonically cleaned in distilled water for at least 5 minutes, then ultrasonically cleaned in anhydrous ethanol for at least 5 minutes, and dried until the silicon substrate is bright.

[0014] According to the above scheme, in step (1), the purity of the cadmium telluride target is not less than 99.9%, wherein the atomic ratio of Cd to Te in the cadmium telluride alloy target is 1:1, and the target-substrate distance is 90mm-100mm.

[0015] According to the above scheme, in step (2), the bias voltage is 700V-800V, the pulse duty cycle is 50%-80%, the RF power supply sputtering power is 30W-50W, the argon flow rate is 60sccm-80sccm, and the working pressure is 2.0Pa-3.0Pa. The preferred concentration of the high-purity argon gas used is 99.999%.

[0016] According to the above scheme, before thin film sputtering in step (3), target pre-sputtering is required to remove contaminants from the target surface. During pre-sputtering, the vacuum level is maintained at 3.0 × 10⁻⁶. -4 Pa-5.0×10 -4 Pa, the working gas is high-purity argon, the argon flow rate is 40sccm-50sccm, the working pressure is 1.5Pa-2.0Pa, the RF sputtering power is adjusted to 30W-50W, and the pre-sputtering time is 15min-25min.

[0017] According to the above scheme, in step (3), the vacuum degree should be 3.0 × 10⁻⁶. -4 Pa-5.0×10 -4 Pa, substrate stage speed is 10r / min-15r / min, sputtering temperature is 20℃-100℃, RF power supply sputtering power is 30W-50W, working gas flow rate is 45sccm-80sccm, and working gas pressure is 1.5Pa-3.0Pa.

[0018] According to the above scheme, in step (3), the continuous sputtering time is 20min-30min each time, and the stop sputtering time is 20min-30min. This cycle is repeated so that the sputtering time reaches 3h-5h.

[0019] According to the above scheme, after step (3) is completed, the film sputtering needs to be stabilized in a high vacuum environment for 1 to 2 hours.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] This invention utilizes magnetron sputtering technology to prepare cadmium telluride thin films with highly ductile ultra-nanotwin and equiaxed crystal structures by periodically shutting off the sputtering power supply during the sputtering process within a set operating temperature and pressure range.

[0022] Most reported thin films currently exist in columnar crystal structures. This invention, by controlling the working gas pressure and employing intermittent sputtering at a specific temperature, prepares ultra-nano-twinned and equiaxed cadmium telluride thin films with grain sizes and twin layer thicknesses both less than 10 nm, exhibiting both ultra-nano-twinned and equiaxed crystal structures. Increasing the working gas pressure reduces the mean free path of gas molecules, leading to an increase in the number of collisions between target atoms and gas molecules during their journey from the target to the substrate, resulting in significant energy loss. Some target atoms will move away from the substrate after multiple collisions, resulting in lower energy and fewer atoms reaching the substrate, thus reducing the deposition rate. On the other hand, increasing the working temperature increases the diffusion rate of target atoms on the substrate deposition surface, potentially leading to larger grain sizes or non-uniform agglomeration and nucleation of target atoms on the substrate surface due to excessively high sputtering rates. Both of these are detrimental to the preparation of ultra-nano-scale equiaxed crystals. Therefore, this invention selects a working temperature range of 25℃-75℃, which has minimal impact on grain size and twin layer thickness. Furthermore, the intermittent sputtering method, which regularly interrupts film growth during sputtering, allows for sufficient relaxation of the film surface. Simultaneously, atomic rearrangement lowers the surface energy, facilitating the adsorption, nucleation, expansion, and growth of target atoms on the substrate surface. By controlling the working gas pressure and employing intermittent sputtering, the cadmium telluride film achieves an equiaxed crystal structure. This equiaxed crystal structure exhibits good isotropic properties, and during compression, it demonstrates excellent strength and plasticity through coordinated deformation processes at grain boundaries, such as lattice distortion, grain torsion, and merging.

[0023] The working pressure range mentioned in this invention is 1.5Pa-3.0Pa, and the working temperature range is 25℃-75℃. Within this control range, combined with the intermittent sputtering method, cadmium telluride thin films with equiaxed crystal structure and containing a large number of nanotwins can be prepared. Moreover, the films have good plasticity and can meet the application scenarios of flexible devices. Attached Figure Description

[0024] Figure 1 These are the X-ray diffraction patterns of Example 1 and Comparative Example 1;

[0025] Figure 2These are scanning electron microscope (SEM) images of the cadmium telluride thin film surface prepared under different deposition conditions (i.e., different gas pressures and whether or not intermittent sputtering method is used), with a magnification of 50,000x (a is Example 1, b is Comparative Example 1, c is Comparative Example 2).

[0026] Figure 3 These are SEM images of cross-sections of cadmium telluride films under different deposition conditions, magnified at 12,000 times (a is Example 1, b is Comparative Example 1, c is Comparative Example 2).

[0027] Figure 4 These are transmission electron microscope (TEM) images and analysis results of the cross-section of the cadmium telluride thin film prepared in Example 1 (a is the TEM image, b is the high-resolution transmission electron microscope (HRTEM) image of the selected area in a, c is the grain size statistics, d is the aspect ratio statistics, e is the twin wafer thickness statistics).

[0028] Figure 5 This is a schematic diagram of the microstructure of the cadmium telluride thin film under different working gas pressures in Example 3.

[0029] Figure 6 The images show TEM images and analysis results of the cross-section of the cadmium telluride thin film prepared in Comparative Example 1 (a is the TEM image, b is the HRTEM image of the selected area in a, c is the grain size statistics, d is the aspect ratio statistics, and e is the twin layer thickness statistics).

[0030] Figure 7 The images show TEM images and analysis results of the cross-section of the cadmium telluride thin film prepared in Comparative Example 2 (a is the TEM image, b is the selected area electron diffraction and calibration results, c is the grain size statistics, and d is the aspect ratio statistics).

[0031] Figure 8 These are the compressive stress-strain curves of cadmium telluride thin films prepared in Example 1 (1.5 Pa, intermittent sputtering), Example 2 (3.0 Pa, intermittent sputtering), Comparative Example 1 (0.5 Pa, continuous sputtering), and Comparative Example 2 (1.5 Pa, continuous sputtering). Detailed Implementation

[0032] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the implementation of the present invention is not limited thereto.

[0033] Example 1

[0034] A highly ductile cadmium telluride thin film with ultra-nanotwinned and equiaxed crystal structures is prepared by the following steps:

[0035] (1) Substrate pretreatment: The single crystal silicon substrate was ultrasonically cleaned with distilled water and anhydrous ethanol for 5 minutes each, and the substrate surface was dried with a hot air blower before being placed in the sputtering chamber for later use.

[0036] (2) Sputtering preparation: Fix the cadmium telluride alloy target onto the sputtering power source, adjust the target-substrate distance to 90mm-100mm, the sputtering angle to 60°-62°, and after closing the sputtering chamber door, evacuate the chamber to 5×10⁻⁶. -4 Pa, followed by argon ion cleaning of the substrate surface. During substrate cleaning, the vacuum level was maintained at 5 × 10⁻⁶. -4 Pa, working gas is argon with a purity of 99.999%, argon flow rate is 80 sccm, working pressure is 3.0 Pa, bias voltage is 800 V, pulse duty cycle is 50%, and the substrate surface is cleaned for 10 min.

[0037] (3) Pre-sputter the target material to remove contaminants from its surface. During pre-sputtering, the vacuum level is maintained at 5 × 10⁻⁶. -4 The working gas is argon with a purity of 99.999%, the argon flow rate is 45 sccm, the working pressure is 1.5 Pa, the RF sputtering power is adjusted to 40 W, and the pre-sputtering time is 20 min.

[0038] (4) Cadmium telluride thin films were sputtered onto a single-crystal silicon substrate. A vacuum of 3 × 10⁻⁶ was maintained during the RF magnetron sputtering deposition. -4 The sputtering parameters were: Pa, stage speed 15 r / min, operating temperature 50℃, working gas argon (99.999% purity), flow rate 45 sccm, operating pressure 1.5 Pa, RF sputtering power 40 W, and sputtering time 4 h. The RF power was switched off and sputtering stopped for 30 minutes every 30 minutes, repeated 8 times. This was to prevent the continuous deposition of high-energy particles during prolonged sputtering, which could raise the substrate temperature and affect the film grain morphology. Furthermore, stopping sputtering midway hinders grain growth perpendicular to the substrate direction and promotes atomic rearrangement on the film surface to reduce surface energy. This allows subsequent grains to grow in different directions, resulting in a film with better isotropic properties.

[0039] (5) After sputtering is completed, turn off the RF power supply, substrate baffle and argon flow valve in sequence. The film temperature can be removed after the vacuum is broken and the film temperature drops to room temperature in a high vacuum environment.

[0040] Example 2

[0041] A highly ductile cadmium telluride thin film with ultra-nanotwinned and equiaxed crystal structures is prepared by the following steps:

[0042] The only difference between the preparation steps of Example 2 and Example 1 is that in step (4), the argon flow rate is 80 sccm and the working pressure is 3.0 Pa.

[0043] Comparative Example 1

[0044] Comparative Example 1 prepared a nanotwinned cadmium telluride thin film with columnar crystal structure. The preparation steps of Comparative Example 1 are different from those of Example 1 in that: in step (4), the working gas pressure is 0.5 Pa, the argon flow rate is 15 sccm, continuous sputtering is used, the radio frequency sputtering power is 40 W, and the continuous sputtering time is 4 h.

[0045] Comparative Example 2

[0046] Comparative Example 2 prepared a nanotwinned cadmium telluride thin film with columnar crystal structure. The difference between the preparation steps of Comparative Example 2 and Example 1 is that in step (4), continuous sputtering was used, the radio frequency sputtering power was 40W, and the continuous sputtering time was 4h.

[0047] The phase structures of the cadmium telluride thin films prepared in Example 1 and Comparative Example 1 are as follows: Figure 1 The XRD patterns show that all samples exhibit a zincblende structure with no impurity phases.

[0048] SEM images of the cadmium telluride thin films prepared in Example 1, Comparative Example 1, and Comparative Example 2 are shown below. Figure 2 As shown, the magnification is 50,000x. Figure (a) shows the surface morphology of the film prepared by intermittent sputtering at 1.5 Pa in Example 1; Figure (b) shows the surface morphology of the film prepared by continuous sputtering at 0.5 Pa in Comparative Example 1; and Figure (c) shows the surface morphology of the film prepared by continuous sputtering at 1.5 Pa in Comparative Example 2. This indicates that increasing the working pressure reduces the grain size, and the film prepared by intermittent sputtering has a smaller surface roughness than that prepared by continuous sputtering.

[0049] SEM images of the cross-sections of the cadmium telluride thin films prepared in Example 1, Comparative Example 1, and Comparative Example 2 are shown below. Figure 3 As shown, the magnification was 12000 times, and the thicknesses of the cadmium telluride films prepared in Example 1, Comparative Example 1, and Comparative Example 2 were measured to be 1.7 μm, 2.0 μm, and 1.9 μm, respectively. The film prepared by intermittent sputtering in Example 1 had no obvious grain boundaries, while the cadmium telluride film prepared by continuous sputtering had parallel grain boundaries.

[0050] TEM images and statistical results of the cross-section in Example 1 are as follows: Figure 4 As shown, comparing Comparative Examples 1 and 2, high working pressure and intermittent sputtering methods affect the size and aspect ratio of the grains. In Example 1, it was found that the proportion of grains with a size in the range of 5nm-10nm was about 55%, and the proportion in the range of 10nm-14nm was about 35%. The average grain size was 9.7nm when obtained by Gaussian distribution. The aspect ratio of the grains was mainly concentrated in the range of 1.0-1.6, with an average aspect ratio of 1.25. The twin wafer layer thickness was mainly concentrated in the range of 1.18nm-2.54nm, with an average twin wafer layer thickness of 1.8nm.

[0051] Comparative Example 1: TEM images and statistical results are as follows Figure 6 As shown in Figures (a) and (b), the grain morphology is a slender columnar crystal structure. The nanotwins within the grains are parallel to each other and perpendicular to the grain boundaries. The statistical results of grain size, aspect ratio, and twin lamella thickness are shown in Figures (c), (d), and (e). The statistics show that approximately 80% of the grains are distributed in the 13nm-22nm range, with an average grain size of 20nm; approximately 80% of the grains have aspect ratios concentrated in the 9.5-24.5 range, with an average aspect ratio of 14.4; and approximately 80% of the twin lamella thicknesses are between 1.5nm and 5.5nm, with an average twin lamella thickness of 2.5nm. The grain size and aspect ratio of Comparative Example 1 are significantly increased compared to Example 1.

[0052] Comparative Example 2: TEM images and statistical results of the cross-section are as follows Figure 7 As shown, in Comparative Example 1, continuous sputtering resulted in columnar crystal morphology. Statistically, approximately 80% of the grain size was concentrated in the 18nm-30nm range, with aspect ratios concentrated in the 7-19 range. The average grain size was 20nm and the average aspect ratio was 13.5. The grain size and aspect ratio of Comparative Example 2 were significantly increased compared to Example 1.

[0053] Figure 8 The compressive stress-strain curves of the films prepared in Examples 1, 2, 1, and 2 are shown. Examples 1 and 2 are cadmium telluride films with highly plastic ultra-nanotwinned and equiaxed crystal structures prepared by intermittent sputtering. Comparative Examples 1 and 2 are cadmium telluride films with columnar crystal structures. According to the stress-strain curves, the ultimate compressive strength of the columnar cadmium telluride film is 1.25 GPa-1.35 GPa, and the ultimate compressive strain is 5%. The compressive strength of Examples 1 and 2 is 1.18 GPa-1.35 GPa, and the ultimate compressive strain is 15%-30%. Compared with the columnar cadmium telluride films (Comparative Examples 1 and 2), the strength of the examples is comparable, while the plasticity is increased by 3-6 times.

[0054] Example 3

[0055] A highly ductile cadmium telluride thin film with ultra-nanotwinned and equiaxed crystal structures is prepared by the following steps:

[0056] The only difference between the preparation steps of Example 3 and Example 1 is that in step (4), the working gas pressure is set to 1.5 Pa, 2.0 Pa, 2.5 Pa, and 3.0 Pa respectively (wherein, when the working gas pressure is 1.5 Pa and 3.0 Pa respectively, that is, Example 1 and 2).

[0057] Figure 5This summary describes how, in Example 3, equiaxed cadmium telluride nanotwinned films were prepared by intermittent sputtering at an operating temperature of 50°C and an operating pressure range of 1.5 Pa to 3.0 Pa, with pressure increments of 0.5 Pa. The statistical results for the microstructure, i.e., the average grain size and average twinned wafer thickness, are as follows: Figure 5 As shown, the average grain size is less than 10nm, basically in the range of 5nm-10nm, and the average twin layer thickness is in the range of 1.2nm-2.0nm.

[0058] Obviously, the above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a high plasticity cadmium telluride thin film having a super-nanotwin and equiaxed crystal structure, characterized in that, The cadmium telluride alloy is used as a radio frequency sputtering target, argon gas is used as working gas, the surface of the target is bombarded by ionized argon ions, cadmium telluride particles are sputtered and deposited on the surface of the substrate from bottom to top, and the cadmium telluride thin film with super-nanometer twin crystal and equiaxed crystal structure is prepared by controlling the working pressure in the sputtering deposition process and using the intermittent sputtering method at a certain working temperature; wherein the working pressure is 1.5 Pa-3.0 Pa, and the working temperature is 25℃-75℃; the intermittent sputtering method is that sputtering for 20 min-30 min and stopping sputtering for 15 min-30 min is a cycle, and the sputtering is repeated for several cycles to make the total sputtering time be 3 h-5 h.

2. The method for preparing a highly ductile cadmium telluride thin film with ultra-nanotwinned and equiaxed crystal structures according to claim 1, characterized in that, The average equiaxed crystal grain size of the high plasticity cadmium telluride thin film is 5 nm-10 nm, and the average twin crystal layer thickness is 1.2 nm-2.0 nm.

3. The method of claim 1, wherein the method is characterized by: The thickness of the high plasticity cadmium telluride thin film is 1.5 μm-2.0 μm, the ultimate compressive strength is 1.18 GPa-1.35 GPa, and the ultimate compressive strain is 15%-30%.

4. The method for preparing a highly ductile cadmium telluride thin film with ultra-nanotwinned and equiaxed crystal structures according to claim 1, characterized in that, The method comprises the following steps: (1) substrate pretreatment: a single crystal silicon with one side polished is selected as the substrate, ultrasonic cleaning is performed, and the substrate surface is dried with a hair dryer to make the substrate surface bright and free of impurities; the substrate is fixed on a tray and placed in a sputtering chamber for use; (2) sputtering preparation: the cadmium telluride alloy target is fixed on a radio frequency power source, the target-substrate distance is adjusted to 90 mm-100 mm, the sputtering angle is 60°-62°, the sputtering chamber door is closed, the sputtering chamber is pumped to a high vacuum state, argon gas is introduced as working gas and a bias voltage is applied to ionize the argon gas, and the single crystal silicon substrate is cleaned with argon ions for 10 min-20 min; (3) sputtering thin film: the working temperature and working pressure are set according to claim 1, the heating switch is turned on to make the substrate temperature reach the set temperature, the argon gas is introduced through the open stop valve to make the working pressure reach the set value; then the substrate shutter, substrate table rotation switch and radio frequency power source switch are turned on in sequence to sputter the thin film, the total sputtering time reaches 3 h-5 h according to the intermittent sputtering method in claim 1, and the high plasticity cadmium telluride thin film with super-nanometer twin crystal and equiaxed crystal structure is obtained.

5. The method for preparing a highly ductile cadmium telluride thin film with ultra-nanotwin and equiaxed crystal structures according to claim 4, characterized in that, The vacuum degree required for high vacuum environment in sputtering thin film is required to be 5 x 10 -4 Pa or below; argon is high purity argon with purity ≥ 99.999%.

6. The method for preparing a highly ductile cadmium telluride thin film with ultra-nanotwin and equiaxed crystal structures according to claim 4, characterized in that, In step (2), the bias voltage is 700 V-800 V, the pulse duty cycle is 50%-80%, the argon gas flow is 60 sccm-80 sccm, and the working pressure is 2.0 Pa-3.0 Pa.

7. The method for preparing a highly ductile cadmium telluride thin film with ultra-nanotwin and equiaxed crystal structures according to claim 4, characterized in that, The vacuum degree in step (3) is 3.0x10 -4 Pa-5.0x10 -4 The substrate table rotates at 10r / min-15r / min, the sputtering working temperature is 20℃-75℃, the radio frequency power is 30W-50W, the working gas flow is 45sccm-80sccm, and the working gas pressure is 1.5Pa-3.0Pa.

8. The method for preparing a highly ductile cadmium telluride thin film with ultra-nanotwin and equiaxed crystal structures according to claim 4, characterized in that, In step (3), after the thin film sputtering is completed, the high vacuum environment is stabilized for 1 h-2 h.

9. The high plasticity cadmium telluride thin film with super-nanometer twin crystal and equiaxed crystal structure prepared by the preparation method in any one of claims 1-8.

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