In2Se3 wurtzite ferroelectric semiconductor material and preparation method thereof
By preparing non-layered In2Se3 wurtzite ferroelectric semiconductor materials, the problems of harsh preparation processes and performance limitations of existing wurtzite ferroelectric materials have been solved, enabling the application of materials with low coercivity and high spontaneous polarization, which are suitable for high-performance memory devices and sensors.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-09
- Publication Date
- 2026-05-05
AI Technical Summary
Existing wurtzite ferroelectric materials have demanding preparation processes and limited material properties, making it difficult to achieve optoelectronic applications in the visible light range. Furthermore, their polarization reversal is complex and their coercive field is high, which limits their application in micro and nanoelectronic devices.
Two-dimensional In2Se3 sheets were prepared by mechanical tape peeling. The phase transition was controlled by electron beam irradiation, laser irradiation or heating, and combined with external electric field control to form a non-layered In2Se3 wurtzite ferroelectric semiconductor material.
In2Se3 material with low coercivity and high spontaneous polarization intensity has been achieved, which is suitable for high-performance non-volatile memory devices and high-sensitivity sensors. It solves the performance degradation problem of traditional materials in the miniaturization process and broadens the application scope.
Smart Images
Figure CN121985571A_ABST
Abstract
Description
Technical Field
[0001] This invention pertains to the preparation and device technology of silicon-based compatible electronic information functional materials in the field of integrated circuits, specifically an In2Se3 wurtzite ferroelectric semiconductor material and its preparation method. Background Technology
[0002] Ferroelectric materials, due to their spontaneous polarization that can be reversed by an external electric field, play a crucial role in fields such as non-volatile memories, sensors, power conversion devices, and microelectromechanical systems (MEMS). Since the discovery of ferroelectricity in wurtzite (WZ) structures, these materials have rapidly become a research hotspot for next-generation ferroelectric materials due to their excellent combination of high spontaneous polarization intensity and high breakdown field strength, demonstrating application potential beyond traditional perovskite oxides. Among them, ferroelectric semiconductors with wurtzite structures, such as aluminum scandium nitride (AlScN) and zinc magnesium oxide (ZnMgO), are currently the focus of research. These materials typically exhibit excellent piezoelectric response, wide band gaps, and good compatibility with existing semiconductor processes (such as CMOS), demonstrating enormous application potential. However, existing wurtzite ferroelectric materials, whether AlScN or ZnMgO systems, are essentially stable three-dimensional (3D) covalently bonded crystal structures. Their fabrication typically relies on thin film growth techniques such as magnetron sputtering and molecular beam epitaxy, where the desired three-dimensional network structure is formed through atomic layer-by-layer deposition in high-temperature or high-energy plasma environments. Although these materials exhibit excellent properties, their fabrication processes require sophisticated equipment and operate under harsh conditions, and they are mostly wide-bandgap materials, limiting their optoelectronic applications in the visible light range.
[0003] Wurtzite nitride ferroelectric materials, represented by AlScN, possess advantages such as strong spontaneous / piezoelectric polarization, strong ferroelectric properties, high Curie temperature, and CMOS compatibility. They overcome application bottlenecks such as the instability of the ferroelectric phase and incompatibility with mainstream semiconductor process platforms inherent in traditional oxide ferroelectrics, showing promise for applications in 5G communications, power electronics, and artificial intelligence. However, due to the involvement of metal-nitrogen atom co-migration in polarization reversal, the domain dynamics of wurtzite nitride ferroelectrics are more complex than those of traditional oxide ferroelectrics, resulting in a high polarization reversal barrier and challenges such as high coercivity and wake-up behavior. These limitations restrict their large-scale application.
[0004] Although wurtzite ferroelectric materials possess many excellent properties, current research on wurtzite ferroelectric materials is mainly limited to a few simple binary / ternary nitride or oxide compounds, such as AlScN. This limitation, to some extent, restricts our comprehensive and in-depth understanding of the intrinsic ferroelectric physical mechanisms of the wurtzite structure from a broader range of chemical compositions and structural variants. Therefore, actively exploring and discovering novel ferroelectric materials with wurtzite structures has dual significance. First, at the level of basic science, expanding the material system is the cornerstone for understanding the origin and regulation of wurtzite ferroelectricity. Second, at the level of technological application, developing new candidate materials is the only way to achieve performance breakthroughs and meet diverse integration needs. Currently, AlScN-based wurtzite ferroelectric thin films have shown good compatibility with mainstream semiconductor process platforms, making them highly attractive in micro / nanoelectronic devices such as memories, filters, and energy harvesters. However, to further optimize performance, such as reducing coercive field, improving durability, or achieving new functions, such as narrow bandgap semiconductor characteristics, innovation must be made at the material source. Exploring more diverse wurtzite ferroelectrics may lead to the discovery of materials with superior overall performance, such as higher remanent polarization, lower leakage current, better thermal stability, or unique functions, such as optocouplers and piezoelectric-ferroelectric synergy. This would greatly broaden the application scope of wurtzite ferroelectric technology and provide key material support for the development of next-generation high-performance, highly integrated electronic information devices. Summary of the Invention
[0005] In view of this, the purpose of this invention is to overcome the problems existing in the prior art and disclose an In2Se3 wurtzite ferroelectric semiconductor material and its preparation method. This ferroelectric semiconductor material is composed of two elements, In and Se, with a stoichiometric ratio of In:Se = 2:3; In-Se is tetrahedral coordinated, possessing a defective wurtzite structure, where the cation positions are occupied by both In and disordered vacancies, and the anion positions are occupied by Se; the space group is P63mc, and the lattice constants are a = 4.01 Å, b = 4.01 Å, and c = 6.82 Å.
[0006] The technical solution of the present invention is as follows: An In₂Se₃ wurtzite ferroelectric semiconductor material is composed of two elements, In and Se, with a stoichiometric ratio of In:Se = 2:3. The In-Se pair exhibits tetrahedral coordination and a defective wurtzite structure, where the cation sites are occupied by both In and disordered vacancies, and the anion sites are occupied by Se. The material has a space group of P63mc and lattice constants a = 4.01 Å, b = 4.01 Å, and c = 6.82 Å. The material is obtained by using a two-dimensional van der Waals layered In₂Se₃ semiconductor as a precursor, controlling the phase transition from two-dimensional layered In₂Se₃ to non-layered 6H-type or 3R-type In₂Se₃ through electron beam irradiation, laser irradiation, or heating, and then controlling the transition through an applied electric field.
[0007] A method for preparing a novel wurtzite ferroelectric semiconductor material In2Se3 includes the following steps: Step 1: The two-dimensional single-crystal In2Se3 bulk was peeled off using a mechanical tape peeling method to obtain In2Se3 thin film samples of different thicknesses; Step 2: Irradiate the In2Se3 thin film sample obtained in Step 1 using any of the following methods: electron beam irradiation, rapid heating annealing, high-power laser, etc., and use focused ion beam to prepare the sample for transmission. Then, perform atomic structure characterization. It can be confirmed that a non-layered In2Se3 material with a 6H structure (six-layer atomic cycle, hexagonal symmetry) or a 3R structure (three-layer atomic cycle, trigonal symmetry) has been obtained. Step 3: Apply DC current to the non-layered In2Se3 material with a 6H or 3R structure after Step 2. Step 4: Characterize the crystal structure and ferroelectric properties of the novel wurtzite In2Se3 obtained after step 3.
[0008] Furthermore, the mechanical tape peeling method described in step 1 involves placing the In2Se3 block material on 3M transparent tape or PET blue film tape, and using the mechanical tape peeling method to fold and stick the tape multiple times, gradually thinning the In2Se3 block into thin sheets of different thicknesses. Then, using tweezers or similar tools, a relatively flat thin sheet sample is removed and placed on a circular iron sheet. Furthermore, the high-power laser irradiation described in step 2 is performed using an InVia InSpect micro Raman spectrometer, and the specific steps are as follows: 21. Focus under a 50x optical microscope and locate a sample area with uniform color and a smooth surface; 22: The laser wavelength was selected as 473 nm, and the power was selected with a 10% ND filter, resulting in a final power of approximately 5.0 mW; 23: The selected locations with uniform and flat color during the fractional irradiation, with a total irradiation time of 20 seconds; 24: Focused ion beam was used to prepare transmission samples, and aberration-corrected transmission electron microscopy was used to characterize the atomic structure.
[0009] Furthermore, step 3 includes: 31: Using a NaOH solution with a concentration of 5 ~ 10 mol / L, tungsten wire is used as the positive electrode and iron wire as the negative electrode to electrochemically corrode the tip of the tungsten wire; 32: Vacuum degree is 1×10 -5 Pa, with the bottom of the sample grounded, the probe in contact with the irradiated area at the top of the sample, and a DC voltage of 0.1~2 V applied; 33: Observe the current reading; its order of magnitude ranges from 10... -9 A increased to 10 -6 A stops powering on.
[0010] Furthermore, the characterization described in step 4 specifically involves preparing the sample after the power is applied in step 3 using a focused ion beam (FIB) for transmission sample preparation, followed by atomic structure characterization using an aberration-corrected transmission electron microscope (AC-TEM).
[0011] This invention provides a novel technical approach in the research and preparation of new silicon-based compatible ferroelectric semiconductor materials. A novel wurtzite ferroelectric semiconductor material is disclosed through the method of this invention. At the application level, it provides an essential path to achieving performance breakthroughs and meeting diverse integration needs. Exploring more diverse wurtzite ferroelectrics is expected to uncover materials with superior overall performance, such as higher remanent polarization, lower leakage current, better thermal stability, or unique functions, such as optocouplers and piezoelectric-ferroelectric synergy, thereby greatly expanding the application scope of wurtzite ferroelectric technology and providing key material support for the development of next-generation high-performance, highly integrated electronic information devices.
[0012] The novel wurtzite In2Se3 obtained by the method of this invention shows promising application prospects in terms of performance. Crystal structure analysis reveals that its three-dimensional covalent bonding network and non-centrosymmetric characteristics facilitate the formation of a stronger electric dipole moment. Therefore, its spontaneous polarization intensity and remanent polarization value are predicted to be much higher than its two-dimensional layered parent structure, which is significant for improving the performance of non-volatile memory devices. Compared to the AlScN system, the novel wurtzite In2Se3 semiconductor involved in this invention has a simple composition, strong polarization intensity, low coercive field, suitable bandgap, and silicon-based compatibility, making it an excellent candidate material for the development of in-memory computing devices in the post-Moore's Law era. Crucially, this invention directly observed the flipping behavior of ferroelectric domains in this novel wurtzite In2Se3 under the influence of an external electric field through experimental methods. This observation provides direct and compelling experimental evidence for the ferroelectric functionality of this material, thus validating the technical feasibility of the proposed method. Compared to traditional storage technologies, this novel wurtzite In2Se3-based storage cell not only achieves ultra-low power data read / write through rapid electric field switching, but also maintains non-volatility at extremely thin scales, solving the performance degradation problem of traditional ferroelectric materials during miniaturization. Furthermore, its semiconductor properties demonstrate significant application potential in in-memory computing architectures and high-sensitivity flexible sensors. Attached Figure Description
[0013] Figure 1 a is a light microscope image of the high-power laser irradiation site on the sample; Figure 1 b is Figure 1 a. Cross-sectional transmission electron microscope image of a medium-to-high power laser irradiation site; Figure 2 a represents the Raman spectra before and after step 2; Figure 2 b is the atomic structure diagram after irradiation in step 2; Figure 3 a is a transmission electron microscope image of the probe under DC power-on in step 3; Figure 3 b is a schematic diagram of the probe being DC powered in step 3; Figure 4 This is a diagram showing the preparation process and structural evolution of the novel zinc fiber In2Se3 of this invention.
[0014] Figure 4 The upper part shows the process path: demonstrating the transformation of two-dimensional layered In2Se3 into the 6H / 3R type by light / electric irradiation or heating, and then into a wurtzite structure by electric field modulation. The lower part shows a transmission electron microscope image taken along the
[100] zone axis; Figure 5 a is a cross-sectional transmission electron microscope image of the In2Se3 domain inversion region of wurtzite in the example; Figure 5b is a schematic diagram of the polarization structure of the In2Se3 domain flip region in wurtzite in the embodiment; Detailed Implementation
[0015] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
[0016] This invention provides an In2Se3 wurtzite ferroelectric semiconductor material, composed of In and Se in a stoichiometric ratio of In:Se = 2:3. The In-Se pair exhibits tetrahedral coordination and a defective wurtzite structure, with cation sites occupied by both In and disordered vacancies, and anion sites occupied by Se. The material has a space group of P63mc and lattice constants a = 4.01 Å, b = 4.01 Å, and c = 6.82 Å. The material is obtained by using a two-dimensional van der Waals layered In2Se3 semiconductor as a precursor, controlling the phase transition from two-dimensional layered In2Se3 to non-layered 6H-type or 3R-type In2Se3 through electron beam irradiation, laser irradiation, or heating, and then controlling the transition through an applied electric field.
[0017] Example 1 The novel In2Se3 wurtzite ferroelectric semiconductor material is prepared by the following steps: Step 1: Use mechanical tape peeling method to peel off the two-dimensional single crystal bulk In2Se3 material to obtain thin film In2Se3 samples; Using a mechanical tape peeling method, the In2Se3 block material was placed on 3M transparent tape / PET blue film tape. After the tape was folded and pasted multiple times, the In2Se3 block was gradually thinned into thin sheets of different thicknesses. The thin sheet sample with uniform color and flat surface was removed with tweezers and placed on a circular iron sheet. Step 2: At room temperature and atmospheric pressure, the In2Se3 thin film sample obtained in Step 1 was irradiated with the generated high-power laser by an InVia InSpect micro Raman spectrometer; details are as follows: 21: Focus under a 50x optical microscope and locate a flat sample area; 22: The laser wavelength was selected as 473 nm, and the power was selected with a 10% ND filter, resulting in a final power of approximately 5.0 mW; 23: Irradiate the selected location in fractions, with a total irradiation duration of 20 seconds, such as... Figure 1 As shown.
[0018] 24: Focused ion beam was used to prepare transmission samples, and aberration-corrected transmission electron microscopy was used to characterize the atomic structure.
[0019] Step 3: Apply high-vacuum DC tungsten probe current to the sample after Step 2; 31: Using a 5 mol / L or 10 mol / L NaOH solution, with a tungsten wire as the positive electrode and an iron wire as the negative electrode, electrochemical corrosion is performed on the tip of the tungsten wire; 32: Vacuum degree is 1×10 -5 Pa, with the bottom of the sample grounded, the probe in contact with the irradiated area at the top of the sample, and a DC voltage of 0.1~2 V applied; 33: Observe the current reading; its order of magnitude ranges from 10... -9 A increased to 10 -6 A stops powering on.
[0020] Step 4: Characterize the crystal structure and ferroelectric properties of the novel In2Se3 wurtzite prepared in Step 3. The atomic structure of the sample after applying electricity in Step 3 is characterized using aberration-corrected transmission electron microscopy.
[0021] The obtained transmission electron microscopy (TEM) structural analysis images of the samples are as follows: Figure 4 and 5 As shown, laser irradiation altered the stacking pattern of atomic layers, transforming the material into an intermediate state of 6H-In₂Se₃. Upon application of an electric field, a fundamental phase transition occurred, forming a non-layered wurtzite phase, In₂Se₃. This entire process reveals a novel physical pathway for the transformation from two-dimensional van der Waals crystals to non-layered crystals. Figure 5 Two different polarization directions and domain wall regions were demonstrated, confirming its ferroelectric properties.
[0022] Example 2 Step 2 is: in a high vacuum at room temperature (10 -5 ~10 -6 The In2Se3 thin film sample obtained in step 1 was irradiated with electron beam at a power of Pa; the In2Se3 thin film sample obtained in step 1 was then irradiated with the generated high-power electron beam; the details are as follows: 21: Focus under a 50x optical microscope and locate a flat sample area; 22: Use focused ion beam for transmission sample preparation.
[0023] 23: High vacuum (10) microscopy using aberration-corrected transmission electron microscopy -5 ~10 -6 Electron beam irradiation (Pa), with an irradiation dose range of 2 × 10⁻⁶ Pa. 6 ~ 5×10 6 C / cm 2 .
[0024] 24: After electron beam irradiation, changes in atomic structure were observed using a spherical aberration-corrected transmission electron microscope.
[0025] Steps 1, 3, and 4 of this embodiment are the same as in embodiment 1.
[0026] Example 3 Step 2 involves irradiating the In2Se3 thin film sample obtained in Step 1 using a rapid heating annealing method; the details are as follows: 21: Focus under a 50x optical microscope and locate a flat sample area; 22: In a rapid heating annealing furnace (vacuum degree 10) -4 Place the sample in the container (pa), set the heating rate to 15 ~ 50℃ / s, heat to 500 ~ 700 ℃, and hold for 90 ~ 150 s; 23: Focused ion beam was used to prepare transmission samples, and aberration-corrected transmission electron microscopy was used to characterize the atomic structure.
[0027] Steps 1, 3, and 4 of this embodiment are the same as in embodiment 1.
[0028] It should be understood that those skilled in the art can make improvements or modifications based on the above description, including replacing the In element of the present invention with other elements of the same group, replacing the Se element with other elements of the same group, or using other energy-driven methods, such as heating, electron beam irradiation, etc., to achieve the phase transition from layered In2Se3 to 6H / 3R In2Se3, etc. All such improvements and modifications should fall within the protection scope of the appended claims of the present invention.
Claims
1. An In₂Se₃ wurtzite ferroelectric semiconductor material, composed of two elements, In and Se, with a stoichiometric ratio of In:Se = 2:3; In-Se is tetrahedral coordinated, possessing a defective wurtzite structure, where the cation sites are occupied by both In and disordered vacancies, and the anion sites are occupied by Se; the material has a space group of P63mc, and lattice constants a = 4.01 Å, b = 4.01 Å, c = 6.82 Å; the material is obtained by: using a two-dimensional van der Waals layered In₂Se₃ semiconductor as a precursor, controlling the phase transition from two-dimensional layered In₂Se₃ to non-layered 6H-type or 3R-type In₂Se₃ through electron beam irradiation, laser irradiation, or heating, and then controlling the phase transition through an electric field.
2. A method for preparing the In2Se3 wurtzite ferroelectric semiconductor material as described in claim 1, comprising the following steps: Step 1: The two-dimensional single-crystal In2Se3 bulk was peeled off using a mechanical tape peeling method to obtain In2Se3 thin film samples of different thicknesses; Step 2: Irradiate the In2Se3 thin film sample obtained in Step 1 using any one of the following methods: electron beam irradiation, rapid heating annealing, or high-power laser irradiation. Use a focused ion beam to prepare the transmission sample and then perform atomic structure characterization to confirm that a non-layered In2Se3 material with a 6H or 3R structure has been obtained. Step 3: Apply DC current to the non-layered In2Se3 material with a 6H or 3R structure after Step 2. Step 4: Characterize the crystal structure and ferroelectric properties of the novel wurtzite In2Se3 obtained after step 3.
3. The method for preparing an In₂Se₃ wurtzite ferroelectric semiconductor material according to claim 1, characterized in that, The mechanical tape peeling method described in step 1 involves placing the bulk In2Se3 material on 3M transparent tape or PET blue film tape, folding and pasting the tape multiple times, gradually thinning the In2Se3 bulk material into sheets of different thicknesses, and then removing a sample of the sheet with a flat surface and placing it on a silicon wafer.
4. The method for preparing an In₂Se₃ wurtzite ferroelectric semiconductor material according to claim 1, characterized in that, The high-power laser irradiation mentioned in step 2 is performed using a micro Raman spectrometer. The specific steps are as follows: 21: Focus under a 50x magnification microscope and locate a sample area with uniform and smooth color; 22: The laser wavelength was selected as 473 nm, and the power was selected with a 10% ND filter, resulting in a final power of approximately 5.0 mW; 23: The selected locations with uniform and flat color during the fractional irradiation, with a total irradiation time of 20 seconds; 24: Focused ion beam was used to prepare transmission samples, and aberration-corrected transmission electron microscopy was used to characterize the atomic structure.
5. The method for preparing an In₂Se₃ wurtzite ferroelectric semiconductor material according to claim 1, characterized in that, Step 3 includes: 31: Using a NaOH solution with a concentration of 5 ~ 10 mol / L, tungsten wire is used as the positive electrode and iron wire as the negative electrode to electrochemically corrode the tip of the tungsten wire; 32: Vacuum degree is 1×10 -5 Pa, the bottom of the sample is grounded, the probe contacts the irradiated position on the top of the sample, and a DC voltage of 0.1~2 V is applied; 33: Observe the change in the current reading; its order of magnitude changes from 10... -9 A increased to 10 -6 A stops powering on.
6. The method for preparing an In₂Se₃ wurtzite ferroelectric semiconductor material according to claim 1, characterized in that, The characterization described in step 4 is to perform atomic structure characterization on the sample after applying electricity in step 3.