Method for inducing two-dimensional semiconductor to generate ferroelectricity through ion regulation and control and application
By embedding alkali metal ions into the two-dimensional semiconductor material Bi2O2Se using an ion modulation method, the problem of difficulty in introducing ferroelectricity in existing technologies has been solved, and the preparation of ferroelectric materials has been realized, which are suitable for non-volatile memories, optoelectronic integrated devices and energy devices.
Patent Information
- Application Number
- CN202511035305.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-25
- Publication Date
- 2025-12-09
Smart Images
Figure CN121099674A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of two-dimensional semiconductor materials, and particularly relates to a method for inducing ferroelectricity of two-dimensional semiconductors by ion regulation and application. BACKGROUND
[0002] The progress of material science, especially the development of new materials, is an important driving force for social development. As the preparation process of silicon-based chips approaches the physical limit, the problems of short channel effect and thermal effect are increasingly prominent, and semiconductor technology has entered the post-moore era. To continue Moore's law and achieve high-performance chips, the development of new materials is the key to breaking through the above bottlenecks. Two-dimensional materials, with their atomic-level thickness advantage, can effectively suppress the short channel effect, and are therefore considered as a strong candidate for the next generation of semiconductor devices. In addition, two-dimensional materials also have excellent electrical properties, such as high carrier mobility, tunable band gap, etc., whose properties cover the range of conductors, semiconductors and insulators, showing great potential for building electronic devices.
[0003] Among the many candidate materials, quasi-two-dimensional semiconductor Bi2O2Se has attracted widespread attention due to its unique comprehensive performance. This material has an ideal band gap of about 0.8 eV, an ultra-high carrier mobility (1.9 K temperature, up to 29000 cm 2 / (V·s), still maintaining 450 cm 2 / (V·s) at room temperature), a current switching ratio of more than 10 6 , and a subthreshold swing close to the theoretical limit (~65 mV / dec). These excellent properties make it have great application potential in the fields of logic devices, memory devices, sensors, photodetectors, etc.
[0004] The crystal structure of Bi2O2Se belongs to the I4 / mmm space group, which is a central symmetric structure, and is formed by the alternating arrangement of Bi2O2 layers and Se layers coupled by electrostatic force. It does not have intrinsic ferroelectricity. Therefore, it is of great significance to regulate Bi2O2Se through other means to induce its ferroelectricity to expand its application range. At present, researchers have found through first-principles calculations that applying biaxial strain can induce significant ferroelectric polarization in non-ferroelectric Bi2O2Se (polarization intensity up to 56.1 μC / cm 2 under 4.1% strain), and its piezoelectric coefficient is about 35 times that of monolayer MoS2. Based on the above theoretical prediction, existing technologies have verified through experiments that Bi2O2Se ultra-thin (about 2 nm) single crystal nanosheet has ferroelectricity. These findings make Bi2O2Se material promising for applications in ultra-high density non-volatile memory, ultra-low power logic devices, neuromorphic computing and brain-like chips, etc.
[0005] Although structural distortions can be introduced into Bi₂O₂Se materials through strain engineering to induce ferroelectricity, its practical application faces significant challenges. Unlike typical two-dimensional layered materials bound by weak van der Waals forces, [Bi₂O₂] in Bi₂O₂Se... 2+ Layers and [Se] 2- The layers are coupled by strong electrostatic forces. Therefore, it is difficult to obtain their ultrathin structures using traditional methods suitable for van der Waals materials, such as mechanical exfoliation. This preparation challenge severely restricts the development and application of Bi₂O₂Se and similar materials. Therefore, developing mild and controllable novel preparation techniques is crucial to overcoming traditional limitations. Summary of the Invention
[0006] The problem to be solved by the present invention is to provide a method and application for inducing ferroelectricity in two-dimensional semiconductors by ion modulation, so as to overcome the shortcomings of existing technologies such as reducing thickness and interfacial strain to induce ferroelectricity through structural distortion which are difficult to apply in practice.
[0007] The technical solution adopted by this invention to solve its technical problem is: a method for inducing ferroelectricity in a two-dimensional semiconductor by ion modulation, comprising the following steps: S1, according to the type of ion to be inserted, a corresponding alkali metal is provided, and the alkali metal and aromatic hydrocarbon compound are added to an ether solvent and dissolved to form a mixed solution; S2, dilute the mixed solution prepared in S1 to obtain an alkali metal-aromatic hydrocarbon pre-doped solution; S3, the two-dimensional semiconductor material is completely immersed in the alkali metal-aromatic hydrocarbon pre-doped solution prepared in S2, and after standing for a predetermined time, the alkali metal ions are embedded into the lattice or surface structure of the two-dimensional semiconductor material. S4. Take out the two-dimensional semiconductor material processed in S3, wash and dry it repeatedly to finally obtain the two-dimensional semiconductor material doped with ions, and the two-dimensional semiconductor material doped with ions is induced to produce ferroelectricity.
[0008] As a further improvement of the present invention, in S1, the alkali metal is lithium metal, the aromatic hydrocarbon compound is biphenyl, and the ether solvent is tetrahydrofuran.
[0009] As a further improvement of the present invention, the mass ratio of the alkali metal to the aromatic hydrocarbon compound is 1:(15~25); the volume of the ether solvent is 100~200mL per gram of the alkali metal, which is based on the initial amount used to dissolve the alkali metal and the aromatic hydrocarbon compound.
[0010] As a further improvement of the present application, in the S2, the mixed solution prepared in the S1 is diluted by the same ether solvent as in the S1, and the dilution ratio is between 800 times and 1200 times, and the obtained alkali metal- aromatic hydrocarbon pre-doped solution is a LiBP pre-lithiation solution.
[0011] As a further improvement of the present application, the two-dimensional semiconductor material in the S3 is a Bi2O2Se material.
[0012] As a further improvement of the present application, the standing time is 6-48h.
[0013] As a further improvement of the present application, in the S4, the removed two-dimensional semiconductor material is repeatedly washed by the same ether solvent as in the S1.
[0014] As a further improvement of the present application, the drying steps in the S1 and the S4 are both completed in an inert gas atmosphere or a vacuum environment.
[0015] The two-dimensional semiconductor material doped with the ions obtained by the method for inducing ferroelectricity of two-dimensional semiconductor material by ion regulation according to the above can be applied to the preparation of a non-volatile memory, a photoelectric integrated device or an energy device.
[0016] The present application has the following beneficial effects: the present application provides a method for inducing ferroelectricity of two-dimensional semiconductor material by ion regulation and application, adopts ion liquid phase embedding strategy, directly induces ferroelectricity in bulk two-dimensional semiconductor material through liquid phase embedding of alkali metal ions, realizes lattice regulation through chemical embedding method, effectively avoids the technical limitations of physical stripping, and has moderate and controllable process, low cost and convenient operation, which is very suitable for large-scale commercial application; at the same time, by regulating ion concentration, standing time and other parameters, the ion embedding amount and depth can be accurately controlled, the adjustability is good, the original high carrier mobility, ideal band gap and other excellent electrical properties of the two-dimensional semiconductor material can be maintained while inducing ferroelectricity, which lays a foundation for device application. BRIEF DESCRIPTION OF DRAWINGS
[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows.
[0018] Figure 1 The step block diagram of the method for inducing ferroelectricity of two-dimensional semiconductor material by ion regulation of the present application; Figure 2 The process diagram of doping lithium ions into Bi2O2Se of the present application; Figure 3 Figure (a) is an X-ray diffraction spectrum of Bi2O2Se; Figure 3 Fig. 6 is an X-ray diffraction spectrum of Li-Bi2O2Se prepared according to the present application; Figure 4 Fig. 6 is an X-ray diffraction spectrum of Li-Bi2O2Se prepared according to the present application; Figure 4 Fig. 6 is an X-ray diffraction spectrum of Li-Bi2O2Se prepared according to the present application; Figure 4 Fig. 6 is an X-ray diffraction spectrum of Li-Bi2O2Se prepared according to the present application; + Fig. 6 is an X-ray diffraction spectrum of Li-Bi2O2Se prepared according to the present application; Figure 4 Fig. 6 is an X-ray diffraction spectrum of Li-Bi2O2Se prepared according to the present application; Figure 4 Fig. 6 is an X-ray diffraction spectrum of Li-Bi2O2Se prepared according to the present application; 3+ Fig. 6 is an X-ray diffraction spectrum of Li-Bi2O2Se prepared according to the present application; Figure 5 Fig. 6 is an X-ray diffraction spectrum of Li-Bi2O2Se prepared according to the present application; Figure 5 Fig. 6 is an X-ray diffraction spectrum of Li-Bi2O2Se prepared according to the present application; Figure 5 Fig. 6 is an X-ray diffraction spectrum of Li-Bi2O2Se prepared according to the present application; Figure 5 Fig. 6 is an X-ray diffraction spectrum of Li-Bi2O2Se prepared according to the present application; DETAILED DESCRIPTION
[0019] Obviously, the embodiments described above are only some but not all of the embodiments of the present application. The present application can be implemented or applied in other different specific embodiments, and the details in the present specification can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.
[0020] It is to be appreciated that various aspects of the embodiments described below are presented for illustration and that the described aspects are merely examples of the many aspects of the application. Any feature, structure, or function described in relation to an aspect can be combined in any way with any other aspect or feature described in relation to any other aspect. It is further appreciated that the aspects described below can be implemented in hardware, software, firmware, or any combination thereof. It is further appreciated that the aspects described below can be implemented in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or a system that converts a computer-readable medium into other computer-readable media. Computer-readable media include both volatile and nonvolatile media used to store information and instructions for use by or in connection with an instruction execution system, apparatus, or device. Computer-readable media include, but are not limited to, magnetic storage devices, optical storage devices, and any other storage devices that store data and instructions for use by or in connection with an instruction execution system, apparatus, or device. The term "computer-readable medium" includes both volatile and nonvolatile media, removable and non-removable media, and computer-readable media encoded in any computer-readable language. The term "computer-readable medium" includes the Internet and intranets, as well as all forms of computer-readable media.
[0021] It is also to be understood that the present application will be described in terms of a few embodiments only, and that with specific embodiments, numerous details, variations, alternatives, modifications and equivalent materials to those described herein can be resorted to by persons skilled in the art. It is therefore contemplated that the application cover any and all modifications, variations, alternatives and equivalents expected to fall with the scope of the present application. Accordingly, while the specification includes examples, the application's scope is indicated by the following claims.
[0022] Furthermore, in the following description, numerous specific details are set forth in order to provide a thorough understanding of the examples. However, it will be apparent to one skilled in the art that the examples can be practiced without these specific details.
[0023] The technical solutions provided by the embodiments of the present application are described below with reference to the drawings.
[0024] Referring to Figure 1 The present application provides a method for inducing ferroelectricity of a two-dimensional semiconductor by ion regulation, comprising the following steps S1-S4.
[0025] S1, providing an alkali metal corresponding to the ion to be embedded, adding the alkali metal and an aromatic compound into an ether solvent to form a mixed solution after dissolution.
[0026] The mass ratio of the alkali metal to the aromatic compound is 1: (15-25), and the volume of the ether solvent is 100-200 mL per gram of the alkali metal, which is based on the initial amount used for dissolving the alkali metal and the aromatic compound.
[0027] S2, diluting the mixed solution prepared in S1 to obtain an alkali metal-aromatic compound pre-doped solution.
[0028] The solvent used for dilution is the same as the ether solvent used in S1.
[0029] Preferably, the dilution multiple is between 800 and 1200.
[0030] S3, immerse the two-dimensional semiconductor material completely into the alkali metal-arene pre-doping solution prepared in S2, and let the alkali metal ions embed into the crystal lattice or surface structure of the two-dimensional semiconductor material after standing for a predetermined time.
[0031] Preferably, the predetermined time for standing is 6-48h.
[0032] S4, take out the two-dimensional semiconductor material treated in S3, and finally obtain the two-dimensional semiconductor material doped with ions after repeated washing and drying, and the two-dimensional semiconductor material doped with ions is induced to have ferroelectricity.
[0033] The solvent used in the washing step is the same as the ether solvent used in S1.
[0034] The drying step in S1 and S4 in the present application is completed in an inert gas atmosphere or a vacuum environment.
[0035] The present application initiates a new path of ion liquid embedding to induce ferroelectricity, adopts ion liquid embedding strategy, directly induces ferroelectricity in bulk two-dimensional semiconductor material through liquid phase embedding of alkali metal ions, realizes lattice regulation through chemical embedding method, effectively avoids the technical limitations of physical peeling, and has the advantages of mild and controllable process, low cost, and convenient operation, which is very suitable for large-scale commercial application. At the same time, by adjusting the ion concentration, standing for a predetermined time and other parameters, the ion embedding amount and depth can be accurately controlled, and the adjustability is good. While inducing ferroelectricity, the two-dimensional semiconductor material can maintain its original high carrier mobility, ideal band gap and other excellent electrical properties, laying a foundation for device application.
[0036] As shown in Figure 2 The present application is specifically described in detail by taking doping of Li ions in Bi2O2Se material as an example.
[0037] In the present embodiment, the alkali metal is specifically lithium metal, the arene compound is specifically biphenyl, the ether solvent is specifically tetrahydrofuran, and the two-dimensional semiconductor material is specifically Bi2O2Se material.
[0038] S1, under an inert gas atmosphere such as argon or a vacuum environment, weigh 0.1g of lithium metal and 2.2g of biphenyl, add to 15ml of tetrahydrofuran solvent, stir for 12h to make the solid completely dissolved, and form an opaque dark blue-black mixed solution.
[0039] S2, dilute the mixed solution obtained in S1 with the same ether solvent, i.e. tetrahydrofuran, by 1000 times to obtain a LiBP pre-lithiation solution of 0.0667mg / ml.
[0040] S3, immerse the Bi2O2Se material completely into a predetermined volume of LiBP pre-lithiation solution prepared according to S2, and let the immersed Bi2O2Se material stand at room temperature for a predetermined time of 12 h, so as to enable lithium ions to be effectively embedded or doped into the crystal lattice or surface structure of the Bi2O2Se material.
[0041] It is worth mentioning that the amount of Li ion embedding can be regulated by adjusting the standing time, for example, 6 h or 24 h, so as to achieve a precisely controllable doping process, and customize key performances such as ferroelectric polarization strength and conductivity according to the requirements of target devices, thereby providing high flexibility for functional design.
[0042] S4, take out the material processed in S3, and wash the taken-out material with the same ether solvent, i.e. tetrahydrofuran, as used in S2, for multiple times, so as to remove residual LiBP pre-lithiation solution and reaction by-products; and then dry the washed material under an inert atmosphere, such as argon or vacuum, to finally obtain Li-Bi2O2Se.
[0043] The Li-Bi2O2Se material prepared by the above method is subjected to performance testing, and the results are as follows: As shown in Figure 3 , wherein (a) is an X-ray diffraction spectrum of Bi2O2Se, and (b) is an X-ray diffraction spectrum of Li-Bi2O2Se prepared by the present application. A Bi2O2Se (BOSe for short) film with a thickness of about 100 nm is epitaxially grown on a STO (strontium titanate) substrate by using a pulsed laser deposition technique. As shown in Figure 3 (a), the X-ray diffraction spectrum shows characteristic diffraction peaks at 29.1°, 44.5°, 60.7° and 78.3°, which correspond to (002)n (n = 1-4) of BOSe (space group: I4 / mmm), thereby confirming the highly single-crystalline nature of the BOSe film. The BOSe sample is immersed in a LiBP pre-lithiation solution for 12 hours, so as to introduce a small amount of lithium ions into the BOSe film. As shown in Figure 3 (b), compared with Figure 3 the initial X-ray diffraction spectrum of BOSe / STO in (a), the diffraction peaks of the BOSe / STO doped with lithium ions do not change, and no new diffraction peaks are observed, which indicates that the insertion of a small amount of lithium ions does not change the crystal structure of BOSe.
[0044] As shown in Figure 4As shown, the Li-Bi2O2Se sample was analyzed using a focused ion beam-scanning electron microscope equipped with a ToF-SIMS (Time of Flight Secondary Ion Mass Spectrometry) module, and the distribution of Li, Bi, Ti and Sr elements was collected in a region with a cross-sectional size of 10 μm x 10 μm and a depth of 300 nm. As shown in Figure 4 As shown in (a) and (b), a large amount of lithium ions exist in the surface region, and the concentration decreases near the BOSe-substrate interface, indicating that the lithium ion concentration gradient drives its diffusion into the BOSe thin film.
[0045] As shown in Figure 5 The ferroelectric properties of Li-Bi2O2Se were verified using a piezoelectric force microscope (PFM) technique. To avoid the interference of electrostatic effects and charge injection on the experimental results, conductive Nb:STO was selected as the substrate, and a BOSe single crystal thin film with a thickness of about 100 nm was epitaxially grown on the surface of the Nb:STO under the same experimental method and conditions. Then, the BOSe / Nb:STO was pre-lithiated. Figure 5 (a) shows the surface morphology obtained by atomic force microscopy (AFM) testing, indicating that the surface is relatively smooth and has no obvious pits caused by corrosion of the pre-lithiation solution. In addition, some obvious small particles are observed on the surface, which are caused by residual lithium salts. By using an AFM probe to scan the BOSe thin film, as shown in Figure 5 (b), the hysteresis of the PFM phase clearly shows a 180° phase shift, and the amplitude signal curve shows the classic butterfly-shaped feature of ferroelectric materials.
[0046] In addition, in order to provide additional evidence of the significant ferroelectric properties of the Li-Bi2O2Se material, the amplitude and phase signals were examined using a probe in a larger area. As shown in Figure 5 (c), the figure shows the amplitude signal distribution characteristics of the ferroelectric domains after applying a bias electric field in different directions on a larger area of the material surface, reflecting the difference in mechanical vibration amplitude of the ferroelectric domains under the action of an alternating electric field, and providing experimental evidence for the ferroelectric response characteristics of the material. As shown in Figure 5 (d), the figure corresponds to the same area as Figure 5 (c), and shows the phase signal distribution of the ferroelectric domains after applying a bias electric field in different directions, and the domain pattern with a 180° phase shift is observed, corresponding to the reversal of the polarization direction of the ferroelectric domains, directly confirming the significant ferroelectric properties of the lithium-doped Bi2O2Se material.
[0047] Therefore, the application first proposes to use Li ion liquid phase embedding strategy to successfully induce ferroelectricity in Bi2O2Se body phase material with strong ionic bond, and the method realizes lattice regulation through chemical embedding, and effectively avoids the technical limitations of physical stripping.
[0048] The doped ion two-dimensional semiconductor material (such as Li-Bi2O2Se) prepared by the method for inducing ferroelectricity of two-dimensional semiconductor by ion regulation as described above has both ferroelectricity and semiconductor characteristics, and can be directly used for preparing non-volatile memory, optoelectronic integrated devices and energy devices (such as ferroelectric photovoltaic devices), and has important application value in the next generation of electronic information and new energy fields.
[0049] In addition, the Li ion liquid phase embedding strategy proposed by the application has universality, and is not only suitable for Bi2O2Se, but also can be extended to other two-dimensional semiconductor materials (such as transition metal sulfide, black phosphorus, etc.), and ferroelectricity, ferromagnetism or superconductivity can be induced by selecting ion species (such as Na + , K + ) embedding, and a novel material platform is provided for neuromorphic computing, ultra-low power memory and other new devices.
[0050] In the specification, the same and similar parts among various embodiments can be referred to each other, and each embodiment focuses on the difference from other embodiments.
[0051] The above is only a specific implementation of the application, but the protection scope of the application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed in the application, which should be covered in the protection scope of the application. Therefore, the protection scope of the application should be subject to the protection scope of the claims.
Claims
1. A method for inducing ferroelectricity in a two-dimensional semiconductor by ion modulation, characterized in that, Includes the following steps: S1, according to the type of ion to be inserted, a corresponding alkali metal is provided, and the alkali metal and aromatic hydrocarbon compound are added to an ether solvent and dissolved to form a mixed solution; S2, dilute the mixed solution prepared in S1 to obtain an alkali metal-aromatic hydrocarbon pre-doped solution; S3, the two-dimensional semiconductor material is completely immersed in the alkali metal-aromatic hydrocarbon pre-doped solution prepared in S2, and after standing for a predetermined time, the alkali metal ions are embedded into the lattice or surface structure of the two-dimensional semiconductor material. S4. Take out the two-dimensional semiconductor material processed in S3, wash and dry it repeatedly to finally obtain the two-dimensional semiconductor material doped with ions, and the two-dimensional semiconductor material doped with ions is induced to produce ferroelectricity.
2. The method for inducing ferroelectricity in a two-dimensional semiconductor by ion modulation according to claim 1, characterized in that: In S1, the alkali metal is lithium metal, the aromatic hydrocarbon compound is biphenyl, and the ether solvent is tetrahydrofuran.
3. The method for inducing ferroelectricity in a two-dimensional semiconductor by ion modulation according to claim 2, characterized in that: The mass ratio of the alkali metal to the aromatic hydrocarbon compound is 1:(15~25); the volume of the ether solvent is 100~200mL per gram of the alkali metal, which is the initial amount used to dissolve the alkali metal and the aromatic hydrocarbon compound.
4. The method for inducing ferroelectricity in a two-dimensional semiconductor by ion modulation according to claim 2, characterized in that: In step S2, the mixed solution prepared in step S1 is diluted using the same ether solvent as in step S1, with the dilution factor between 800 and 1200 times, and the resulting alkali metal-aromatic hydrocarbon pre-doped solution is a LiBP pre-lithiation solution.
5. The method for inducing ferroelectricity in a two-dimensional semiconductor by ion regulation according to claim 2, characterized in that: The two-dimensional semiconductor material in S3 is Bi2O2Se.
6. The method for inducing ferroelectricity in a two-dimensional semiconductor by ion modulation according to claim 5, characterized in that: The settling time is 6 to 48 hours.
7. The method for inducing ferroelectricity in a two-dimensional semiconductor by ion modulation according to claim 5, characterized in that: In step S4, the extracted two-dimensional semiconductor material is repeatedly washed using the same ether solvent as in step S1.
8. The method for inducing ferroelectricity in a two-dimensional semiconductor by ion modulation according to claim 1, characterized in that: The drying steps in S1 and S4 are both completed in an inert gas atmosphere or a vacuum environment.
9. The application of the two-dimensional semiconductor material with doped ions obtained by the method of ion-controlled induction of ferroelectricity in a two-dimensional semiconductor according to any one of claims 1 to 8 in the fabrication of non-volatile memory, optoelectronic integrated devices or energy devices.