Bi1. 8Sm0. 2O3 ferroelectric film as well as preparation method and application thereof

Abstract

The invention provides a Bi < 1.8 > Sm < 0.2 > O < 3 > ferroelectric film as well as a preparation method and application thereof. The preparation method comprises the following steps: taking sapphire subjected to annealing treatment at the temperature of 1100-1300 DEG C as a substrate, bombarding a bismuth oxide samarium target material in a chamber by adopting pulse laser, and depositing on the substrate at the temperature of 450-600 DEG C to form the Bi1. 8Sm0. 2O3 ferroelectric film. The preparation method of the Bi1. 8Sm0. 2O3 ferroelectric film provided by the invention is simple to operate, the production cost of the ferroelectric film is low, a brand new method and thought are provided for the preparation of the Bi1. 8Sm0. 2O3 ferroelectric epitaxial film, and the prepared Bi1. 8Sm0. 2O3 ferroelectric epitaxial film has excellent crystallinity and ferroelectric property.

Description

Technical Field

[0001] The present invention relates to the technical field of ferroelectric materials, and particularly to a Bi 1.8 Sm 0.2 O3 ferroelectric thin film, a preparation method thereof, and an application thereof. Background Art

[0002] Ferroelectric materials are key components of non-volatile memories used as information storage media and field-effect transistors used as gate dielectrics. Bi 1.8 Sm 0.2 O3 thin films are considered to be a promising new type of ferroelectric material due to their excellent ferroelectric properties, high crystallization quality, low leakage characteristics, and application potential in various electronic devices, attracting extensive attention in the academic community. Currently, the growth methods of Bi 1.8 Sm 0.2 O3 thin films are relatively single, mainly concentrated in chemical solution methods. Traditional chemical solution methods are complex in operation, have high requirements for the environment and equipment, and high production costs. Developing a simple, efficient, and controllable high-quality Bi 1.8 Sm 0.2 O3 thin film production process has very important economic value. Summary of the Invention

[0003] Pulsed laser deposition technology can precisely control the thickness and composition of thin films and can achieve thin film growth from the nanoscale to the microscale. By adjusting parameters such as the frequency, energy, deposition oxygen pressure, and deposition time of laser pulses, fine control of the thin film growth process can be achieved. Pulsed laser deposition technology ablates the target material with high-energy laser pulses and deposits the target material on the substrate in the form of plasma to form high-quality epitaxial thin films. Although it is feasible to use pulsed laser deposition technology to prepare Bi 1.8 Sm 0.2 O3 thin films, however, it is found that when pulsed laser deposition technology is applied, there are still cases where the crystallinity of Bi 1.8 Sm 0.2 O3 thin films is low or even ferroelectric Bi 1.8 Sm 0.2 O3 thin films with ferroelectric properties cannot be obtained. Based on this, the present invention proposes a Bi 1.8 Sm 0.2 O3 ferroelectric thin film, a preparation method thereof, and an application thereof.

[0004] Specifically, in the first aspect, the present invention proposes a method for preparing a Bi 1.8 Sm 0.2 O3 ferroelectric thin film, the method comprising: Using sapphire annealed at a temperature of 1100 - 1300 °C as a substrate, a bismuth samarium oxide target is bombarded by pulsed laser in a chamber, and the Bi 1.8 Sm 0.2 O3 thin film is deposited on the substrate at a temperature of 450 - 600 °C.

[0005] According to the method for preparing the Bi 1.8 Sm 0.2 O3 ferroelectric thin film provided by the present invention, sapphire annealed at a temperature of 1100 - 1300 °C is used as a substrate. Annealing treatment can obtain sapphire with a neatly arranged groove surface structure. The atomic reconstruction of the substrate surface forms atomically flat steps on the surface, providing nucleation sites for film deposition, thus significantly improving the film quality. A bismuth samarium oxide target is bombarded by pulsed laser in a chamber. The continuous bombardment of the bismuth samarium oxide target by pulsed laser generates a plasma plume, and the plasma plume is deposited on the substrate to form a Bi 1.8 Sm 0.2 O3 thin film. Through precise control of the pulsed laser, the preparation of high-quality Bi 1.8 Sm 0.2 O3 ferroelectric thin film is realized. Among them, during the film deposition process, the temperature of the substrate is controlled at 450 - 600 °C, which can provide energy for the particles reaching the substrate surface to migrate and rearrange on the substrate, making the Bi 1.8 Sm 0.2 O3 thin film have a high degree of crystallinity and improve the ferroelectric properties of the Bi 1.8 Sm 0.2 O3 thin film. By selecting a sapphire substrate annealed at a certain temperature and controlling the temperature of the substrate during deposition within a certain range, the two work synergistically to jointly prepare a high-quality Bi 1.8 Sm 0.2 O3 thin film. Thus, this method is simple to operate and the production cost of the ferroelectric thin film is low, providing a new method and idea for the preparation of Bi 1.8 Sm 0.2 O3 ferroelectric epitaxial thin film, and the prepared Bi 1.8 Sm 0.2 O3 thin film has excellent crystallinity and ferroelectric properties.

[0006] According to the method for preparing the Bi 1.8 Sm 0.2 O3 ferroelectric thin film provided by the present invention, the distance between the bismuth samarium oxide target and the substrate is 3 cm - 7 cm. The inventor found that controlling the distance between the bismuth samarium oxide target and the substrate has an impact on the Bi 1.8 Sm 0.2The crystallization of the O3 thin film is significantly affected. If the distance between the bismuth samarium oxide target and the substrate is too small, the migration of particles on the substrate surface is hindered by subsequent particles. If the distance between the bismuth samarium oxide target and the substrate is too large, the particle density reaching the substrate surface is too low, which is not conducive to crystallization. Therefore, controlling the distance between the two within the above range can prepare a high-quality Bi 1.8 Sm 0.2 O3 thin film.

[0007] In some embodiments of the present invention, cleaning the surface of the bismuth samarium oxide target before thin film growth can effectively remove the thin layer on the target surface and clean the impurities attached to the target surface.

[0008] In some embodiments of the present invention, before depositing on the substrate, the substrate needs to be heated to reach the deposition temperature. Controlling the heating rate of the substrate at 3-6 °C / min can improve the crystallization quality, uniformity and surface performance of the thin film.

[0009] In some embodiments of the present invention, the sapphire substrate is fixed on the sample stage with silver glue. The role of the silver glue is to conduct heat, so that the temperature of the sample stage can be better transmitted to the substrate, and the thin film growth temperature is more accurate.

[0010] In some embodiments of the present invention, the sapphire is selected from c-plane sapphire, A-plane sapphire, R-plane sapphire or M-plane sapphire, preferably c-plane sapphire (c-plane Al2O3 single crystal).

[0011] According to the method for preparing a Bi 1.8 Sm 0.2 O3 ferroelectric thin film provided by the present invention, the annealing temperature of the sapphire is 1100-1300 °C, and the time is 10h-20h. Controlling the annealing temperature of the sapphire within the above range can reconstruct the atoms on the substrate surface, form atomic steps on the surface, create nucleation sites for thin film deposition, and improve the quality of the Bi 1.8 Sm 0.2 O3 ferroelectric thin film.

[0012] In some embodiments of the present invention, the sapphire annealing treatment is carried out in an oxygen atmosphere with a flow rate of 50-80 sccm.

[0013] In some embodiments of the present invention, during the thin film deposition process, the oxygen pressure in the deposition chamber is controlled at 8-12 Pa.

[0014] In some embodiments of the present invention, before the thin film deposition growth, ensure that the vacuum degree in the chamber is not greater than 10 - 6 mbar, then introduce oxygen into the chamber. When depositing the thin film, the chamber vacuum degree reaches 8-12 Pa.

[0015] In some embodiments of the present invention, the repetition frequency of the pulsed laser is 2 - 7 Hz.

[0016] In some embodiments of the present invention, the energy of the pulsed laser is 300 - 1000 mJ.

[0017] In some embodiments of the present invention, the time for depositing the thin film on the substrate is more than 20 min.

[0018] Preferably, the molar ratio of Bi atoms, Sm atoms, and O atoms in the samarium bismuth oxide target is 1.8:0.2:3.

[0019] In the second aspect of the present invention, the present invention proposes a ferroelectric material, namely Bi 1.8 Sm 0.2 The O3 ferroelectric thin film is prepared by the above method. Thus, the Bi 1.8 Sm 0.2 O3 ferroelectric thin film has high crystalline quality and ferroelectric properties.

[0020] Preferably, the microstructure of the Bi 1.8 Sm 0.2 O3 thin film presents a triangular morphology.

[0021] Preferably, the Bi 1.8 Sm 0.2 O3 thin film has no impurity phase.

[0022] Preferably, the thickness of the Bi 1.8 Sm 0.2 O3 thin film is 30 nm - 340 nm.

[0023] In the third aspect of the present invention, the present invention proposes an electronic device, which includes the above-mentioned Bi 1.8 Sm 0.2 O3 ferroelectric thin film.

[0024] The present invention at least includes the following technical effects: Through precise regulation of the pulsed laser deposition parameters, the present invention can achieve the preparation of high-quality, centimeter-scale area Bi 1.8 Sm 0.2 O3 ferroelectric epitaxial thin films, providing a new method for growing Bi 1.8 Sm 0.2 O3 ferroelectric epitaxial thin films, solving problems such as low safety of Bi 1.8 Sm 0.2 O3 ferroelectric epitaxial thin films, and providing basic conditions for researching and designing high-capacity and energy-saving electronic devices based on Bi 1.8 Sm 0.2 O3 ferroelectric epitaxial thin films. The Bi obtained by the present invention1.8 Sm 0.2 The Bi 1.8 Sm 0.2 O3 thin film has excellent crystallization quality and ferroelectric properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 is the X-ray diffraction pattern of the Bi 1.8 Sm 0.2 O3 ferroelectric thin film in Embodiment 1 of the present invention; 1.8 Sm 0.2 O3 ferroelectric thin film; Figure 2 is the Phi scan result diagram of the Bi 1.8 Sm 0.2 O3 ferroelectric thin film in Embodiment 1 of the present invention; 1.8 Sm 0.2 O3 ferroelectric thin film; Figure 3 is the electron microscope image of the untreated c-plane Al2O3 substrate in Comparative Example 2 of the present invention; Figure 4 is the atomic force microscope image of the annealed c-plane Al2O3 substrate in Embodiment 1 of the present invention; Figure 5 is the X-ray diffraction pattern of the Bi 1.8 Sm 0.2 O3 ferroelectric thin film prepared in Embodiments 1-4 of the present invention; 1.8 Sm 0.2 O3 ferroelectric thin film; Figure 6 is the scanning electron microscope image of the Bi 1.8 Sm 0.2 O3 ferroelectric thin film prepared in Embodiments 1-4 of the present invention; 1.8 Sm 0.2 O3 ferroelectric thin film; Figure 7 is the X-ray diffraction pattern of the Bi 1.8 Sm 0.2 O3 ferroelectric thin film prepared in Embodiments 1, 5, and 6 of the present invention; 1.8 Sm 0.2 O3 ferroelectric thin film; Figure 8 is the X-ray diffraction pattern of the Bi 1.8 Sm 0.2 O3 ferroelectric thin film prepared in Embodiments 1, 5, and 6 of the present invention; 1.8 Sm 0.2 O3 ferroelectric thin film (003) peak full width at half maximum and the calculation result diagram of the out-of-plane lattice constant of the Bi 1.8 Sm 0.2 O3 ferroelectric thin film; 1.8 Sm 0.2 O3 ferroelectric thin film; Figure 9 is the cross-sectional scanning electron microscope image of the Bi 1.8 Sm 0.2 O3 ferroelectric thin film at different magnifications in Embodiment 7 of the present invention; 1.8 Sm 0.2 O3 ferroelectric thin film; Figure 10is the piezoresponse force microscopy image of the Bi 1.8 Sm 0.2 O3 ferroelectric thin film prepared in Example 1 of the present invention; Figure 11 is the cross-sectional scanning transmission electron microscopy image of the Bi 1.8 Sm 0.2 O3 ferroelectric thin film in Example 8 of the present invention; Figure 12 is the X-ray diffraction pattern of the Bi 1.8 Sm 0.2 O3 ferroelectric thin film in Comparative Example 1 of the present invention; Figure 13 is the atomic force microscopy image of the annealed c-plane Al2O3 substrate in Comparative Example 5 of the present invention; Figure 14 is the atomic force microscopy image of the annealed c-plane Al2O3 substrate in Comparative Example 6 of the present invention. Detailed implementation manners

[0027] Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. The present invention will be described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0028] The c-plane Al2O3 substrates used in this example and the comparative examples were purchased from Nanjing Muke Nano Technology Co., Ltd., with a specification of 5x5x0.43 mm; commercial brand: MK1201 / 1344-28-1.

[0029] Example 1 This example provides a Bi 1.8 Sm 0.2 O3 ferroelectric thin film, and its preparation process is as follows: (1) Place a 0.5 cm * 0.5 cm c-plane Al2O3 substrate in an alumina ceramic boat and anneal it in an oxygen atmosphere at 1200 °C for 15 hours to obtain a c-plane sapphire with a neatly arranged groove surface structure.

[0030] (2) Using bismuth oxygen samarium with a molar ratio of bismuth, samarium, and oxygen of 1.8:0.2:3 as the target, when the vacuum degree of the main chamber is less than 10 -6 mbar, pre-sputter in an oxygen atmosphere with a main chamber vacuum of 10 Pa for 30 min (during the pre-sputtering process, the baffle is placed between the target and the substrate, and no film grows on the substrate. After the pre-sputtering ends, the baffle between the target and the substrate is removed, and continuous bombardment sputtering is carried out). After the pre-sputtering ends, start growing Bi 1.8 Sm 0.2O3, the growth time is 30 min, the laser repetition frequency is 5 Hz, the energy of the pulsed laser is 380 mJ, the growth oxygen pressure is 10 Pa, the laser irradiates on the target, the substrate temperature is controlled at 500 °C, and the distance between the target and the substrate is 5 cm.

[0031] Example 2 This example provides a Bi 1.8 Sm 0.2 O3 ferroelectric thin film. The difference in its preparation process from Example 1 is: The substrate temperature is controlled at 450 °C.

[0032] Example 3 This example provides a Bi 1.8 Sm 0.2 O3 ferroelectric thin film. The difference in its preparation process from Example 1 is: The substrate temperature is controlled at 550 °C.

[0033] Example 4 This example provides a Bi 1.8 Sm 0.2 O3 ferroelectric thin film. The difference in its preparation process from Example 1 is: The substrate temperature is controlled at 600 °C.

[0034] Example 5 This example provides a Bi 1.8 Sm 0.2 O3 ferroelectric thin film. The difference in its preparation process from Example 1 is: The distance between the target and the substrate is 3 cm.

[0035] Example 6 This example provides a Bi 1.8 Sm 0.2 O3 ferroelectric thin film. The difference in its preparation process from Example 1 is: The distance between the target and the substrate is 7 cm.

[0036] Example 7 This example provides a Bi 1.8 Sm 0.2 O3 ferroelectric thin film. The difference in its preparation process from Example 1 is: The growth time is 5 h.

[0037] Example 8 This example provides a Bi 1.8 Sm 0.2 O3 ferroelectric thin film. The difference in its preparation process from Example 1 is: The growth time is 50 min.

[0038] Comparative Example 1 This comparative example provides a Bi 1.8 Sm 0.2 O3 ferroelectric thin film. The difference in its preparation process from that of Example 1 is that: The substrate used is a mica substrate.

[0039] Comparative Example 2 This comparative example provides a Bi 1.8 Sm 0.2 O3 ferroelectric thin film. The difference in its preparation process from that of Example 1 is that: The substrate used is c-plane Al2O3 that has not been annealed.

[0040] Comparative Example 3 This comparative example provides a Bi 1.8 Sm 0.2 O3 ferroelectric thin film. The difference in its preparation process from that of Example 1 is that: The substrate temperature is controlled at 400 °C.

[0041] Comparative Example 4 This comparative example provides a Bi 1.8 Sm 0.2 O3 ferroelectric thin film. The difference in its preparation process from that of Example 1 is that: The substrate temperature is controlled at 650 °C.

[0042] Comparative Example 5 This comparative example provides a Bi 1.8 Sm 0.2 O3 ferroelectric thin film. The difference in its preparation process from that of Example 1 is that: A 0.5 cm * 0.5 cm c-plane Al2O3 substrate is placed in an alumina ceramic boat and annealed in an oxygen atmosphere at 1400 °C for 15 hours.

[0043] Comparative Example 6 This comparative example provides a Bi 1.8 Sm 0.2 O3 ferroelectric thin film. The difference in its preparation process from that of Example 1 is that: A 0.5 cm * 0.5 cm c-plane Al2O3 substrate is placed in an alumina ceramic boat and annealed in an oxygen atmosphere at 1000 °C for 15 hours.

[0044] The properties of the Bi 1.8 Sm 0.2 O3 thin films of the examples and comparative examples were measured, and the details are as follows: The X-ray diffraction pattern of the Bi 1.8 Sm 0.2 O3 ferroelectric thin film of Example 1 is as Figure 1As shown, the grown Bi 1.8 Sm 0.2 O3 thin film has high crystallinity and almost no impurities are generated.

[0045] The Bi 1.8 Sm 0.2 Phi scan result diagram of the O3 ferroelectric thin film is as shown in Figure 2 As shown, the Phi scan result shows that Bi 1.8 Sm 0.2 O3 has a very sharp (002) diffraction peak, which completely corresponds to the (012) diffraction peak of c-plane Al2O3, indicating the symmetry of Bi 1.8 Sm 0.2 O3 and confirming the epitaxial growth of Bi 1.8 Sm 0.2 O3 on c-plane Al2O3.

[0046] The untreated c-plane Al2O3 substrate of Comparative Example 2 has an atomically flat surface, as shown in Figure 3 As shown.

[0047] The atomic force microscope (AFM) image of the annealed c-plane Al2O3 substrate of Example 1 is as shown in Figure 4 As shown, compared with Figure 3 , it can be seen from Figure 4 that annealing reconstructs the surface atoms of the substrate, and atomically flat steps are formed on the surface, providing nucleation sites for film deposition.

[0048] The X-ray diffraction patterns of the Bi 1.8 Sm 0.2 O3 ferroelectric thin films prepared in Examples 1-4 are as shown in Figure 5 As shown, the X-ray diffraction results show that the Bi 1.8 Sm 0.2 O3 thin films grown in the range of 450 °C - 600 °C have high crystallinity, and almost no impurities are detected, and no second phase appears during the entire film growth process.

[0049] The scanning transmission electron microscope images of the Bi 1.8 Sm 0.2 O3 ferroelectric thin films prepared in Examples 1-4 are as shown in Figure 6 As shown, it can be seen from Figure 6 that clear and obvious triangular morphologies can be observed in the scanning transmission electron microscope images of the Bi 1.8 Sm 0.2 O3 thin films prepared at different temperatures.

[0050] The Bi 1.8 Sm0.2 The X-ray diffraction pattern of the Bi Figure 7 Sm 1.8 Sm 0.2 O3 ferroelectric thin film is as shown. The X-ray diffraction results show that the Bi

[0051] Sm 1.8 Sm 0.2 O3 ferroelectric thin film grown within the range of 3 cm - 7 cm between the target and the substrate has a high degree of crystallinity, and almost no impurities are detected, and no second phase appears during the entire thin film growth process. 1.8 Sm 0.2 The full width at half maximum of the (003) peak of the Bi Figure 8 Sm 1.8 Sm 0.2 O3 ferroelectric thin film and the calculation results of the out-of-plane lattice constant of the Bi

[0052] Sm 1.8 Sm 0.2 O3 ferroelectric thin film at different magnifications are as shown. It can be seen from Figure 9 that there is a clear and obvious boundary between the Bi Figure 9 Sm 1.8 Sm 0.2 O3 ferroelectric thin film and the substrate. Specifically, the thickness of the Bi 1.8 Sm 0.2 O3 thin film grown at a laser repetition frequency of 5 Hz and a laser energy of 380 mJ for 5 h is 340 nm.

[0053] The piezoresponse force microscopy image of the Bi 1.8 Sm 0.2 O3 ferroelectric thin film prepared in Example 1 is as shown. A 4μm * 4μm area on the surface of the thin film was selected for scanning. The PFM test results successfully verified that the spontaneous polarization of the ferroelectric can be regulated by an external electric field. The Bi Figure 10 Sm 1.8 Sm 0.2 O3 thin film of the present invention has excellent ferroelectricity.

[0054] The cross-sectional scanning electron microscopy image of the Bi 1.8 Sm 0.2 O3 ferroelectric thin film in Example 8 is as shown. It can be seen from Figure 11 that the thickness of the Bi Figure 11 Sm 1.8 Sm 0.2 O3 thin film is 60 nm.

[0055] Bi in Comparative Example 11.8 Sm 0.2 The X-ray diffraction pattern of the Bi Figure 12 Sm Figure 12 O3 ferroelectric thin film is shown as follows. It can be seen from 2.33 that only two diffraction peaks of (002) and (003) appear on the mica substrate, indicating a relatively low crystallization quality. Moreover, an impurity peak of Bi2O

[0056] (107) appears in the grown thin film, which may affect the electrical, optical, and chemical stability of the thin film and reduce its performance in practical applications. 1.8 Sm 0.2 O3 ferroelectric thin film cannot be deposited on the surface of c-plane Al2O3 without annealing treatment in Comparative Example 2.

[0057] In Comparative Example 3, when the growth temperature is controlled at 400 °C, Bi 1.8 Sm 0.2 O3 ferroelectric thin film cannot be deposited on the surface of c-plane Al2O3.

[0058] In Comparative Example 4, when the growth temperature is controlled at 650 °C, Bi 1.8 Sm 0.2 O3 ferroelectric thin film cannot be deposited on the surface of c-plane Al2O3.

[0059] The atomic force microscope image of the annealed c-plane Al2O3 substrate in Comparative Example 5 is shown as follows. It can be seen from Figure 13 that although high temperature enhances the migration ability of atoms, it may exceed the equilibrium range of the substrate surface energy, resulting in excessive migration and aggregation of surface atoms, forming irregular steps. These irregular steps may cause additional stress during the cooling process of the substrate, hindering the attachment and growth of the thin film, and resulting in the inability to deposit Bi Figure 13 Sm 1.8 Sm 0.2 O3 ferroelectric thin film on the surface of c-plane Al2O3.

[0060] The atomic force microscope image of the annealed c-plane Al2O3 substrate in Comparative Example 6 is shown as follows. It can be seen from Figure 14 that no regular steps are formed on the surface of the annealed c-plane Al2O3 substrate, and the annealing temperature is too low to cause migration and rearrangement of the substrate surface atoms, resulting in an increase in surface roughness. Due to the lack of regular steps, thin film particles cannot find suitable growth sites, resulting in the inability to deposit Bi Figure 14 Sm 1.8 Sm 0.2 O3 ferroelectric thin film on the surface of c-plane Al2O3.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a ferroelectric material, the ferroelectric material being a Bi 1.8 Sm 0.2 O3 thin film, characterized in that, Comprising: Using sapphire annealed at a temperature of 1100 - 1300 °C as a substrate, a bismuth samarium oxide target is bombarded by pulsed laser in a chamber to deposit the Bi 1.8 Sm 0.2 O3 thin film on the substrate at a temperature of 450 - 600 °C.

2. The preparation method of the ferroelectric material according to claim 1, characterized in that, The distance between the samarium bismuth oxide target and the substrate is 3 cm - 7 cm; And / or, the heating rate of the substrate is 3 - 6 °C / min.

3. The preparation method of the ferroelectric material according to claim 1, characterized in that, The sapphire is selected from c-plane sapphire, A-plane sapphire, R-plane sapphire or M-plane sapphire, preferably c-plane sapphire.

4. The preparation method of the ferroelectric material according to any one of claims 1-3, characterized in that, The annealing time of the sapphire is 10 h - 20 h.

5. The preparation method of the ferroelectric material according to claim 4, wherein The annealing treatment of the sapphire is carried out in an oxygen atmosphere with a flow rate of 50 - 80 sccm.

6. The preparation method of the ferroelectric material according to any one of claims 1-3, characterized in that, The oxygen pressure in the chamber is 8 - 12 Pa.

7. The preparation method of the ferroelectric material according to any one of claims 1-3, characterized in that The repetition frequency of the pulsed laser is 2 - 7 Hz; And / or, the energy of the pulsed laser is 300 - 1000 mJ.

8. The preparation method of the ferroelectric material according to any one of claims 1-3, characterized in that, The time for depositing the film on the substrate is more than 20 min; And / or, the molar ratio of Bi atoms, Sm atoms and O atoms in the samarium bismuth oxide target is 1.8:0.2:

3.

9. A ferroelectric material, characterized in that, Prepared by the preparation method of the ferroelectric material according to any one of claims 1 - 8.

10. An electronic device, characterized in that, Comprising the ferroelectric material according to claim 9.

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