Preparation method of antiferromagnetic CrSb2 single crystal film

Abstract

The invention discloses a preparation method of an antiferromagnetic CrSb2 single crystal film. The preparation method comprises the following steps: step 1, providing a single crystal substrate and a chromium-antimony alloy target material; 2, the substrate is placed in ultrahigh vacuum magnetron sputtering equipment, and the tray is heated under the vacuum condition so that the temperature of the substrate can reach the preset temperature; 3, inert gas is introduced at the preset temperature, and a disordered chromium-antimony compound thin film is deposited on the surface of the substrate through a magnetron sputtering method; 4, continuously keeping the temperature of the substrate at a high temperature in vacuum, and annealing the film; and step 5, naturally cooling the temperature of the substrate to room temperature in vacuum to obtain the CrSb2 single crystal film. According to the preparation method, the anti-ferromagnetic CrSb2 single crystal film can be prepared by utilizing a magnetron sputtering technology.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor technology, and particularly relates to a method for preparing an antiferromagnetic CrSb2 single crystal thin film. Background Art

[0002] Due to their unique spin structures and magnetic properties, antiferromagnetic materials have important application values in the fields of spintronic devices, information storage, and sensors. Spintronics aims to utilize the spin degree of freedom of electrons to transmit and store information. The core lies in precisely controlling and manipulating the spin states of electrons, and then effectively regulating the magnetic structures. Inside antiferromagnetic materials, the magnetic moments are arranged in an antiparallel manner, which endows them with the property of zero net magnetization. However, there is still a strong spin symmetry inside. This special property makes antiferromagnetic materials an ideal platform for studying spin-related effects. Compared with widely used ferromagnetic materials, the torques of ferromagnetic materials are easily reoriented by external environmental interference, and the interference magnetic fields generated inside or outside the memory circuit may cause the stored data to be erased. While antiferromagnets have excellent robustness against charge and magnetic field perturbations. If they can be successfully applied to storage devices, it is expected to overcome this major defect of traditional magnetic storage devices. In addition, antiferromagnetic materials (including semiconductor or insulator materials) with ultrafast magnetic dynamics and room-temperature antiferromagnetic magnetic order have more advantages in performance than traditional ferromagnetic materials. Spin manipulation and signal detection of antiferromagnetic materials by electrical means can not only strongly promote the in-depth application of antiferromagnetic materials in the field of spintronics, but also provide a solid theoretical basis for the development of new low-power, ultrafast-response electronic devices.

[0003] CrSb2 is a narrow-gap semiconductor with a marcasite crystal structure, similar to the crystal structure of FeSb2. Its marcasite phase belongs to an n-type semiconductor with a narrow bandgap of 0.1 eV and exhibits significant anisotropic magnetoresistance in the surface state. It is worth mentioning that CrSb2 is also a topological insulator material, and at the same time has highly anisotropic and antiferromagnetic-ordered semiconductor collinear antiferromagnetic properties. Its Néel temperature Tn = 273K, has a 1×2×2 supercell, and the magnetic moment is perpendicular to the (101) plane. These excellent properties make CrSb2 have great application potential in the field of spintronic devices. At present, most of the research on CrSb2 focuses on the preparation and characteristics of bulk single crystal materials. Although the research on bulk materials provides an important basis for us to deeply understand the basic properties of CrSb2, in practical applications, thin film materials often have unique advantages, such as better compatibility with modern micro-nano processing technology, which is convenient for the miniaturization and integration of devices. Magnetron sputtering, as a common and efficient thin film deposition technology, has significant advantages in the preparation of various thin film materials, such as metals, oxides, semiconductors, and magnetic materials. It has high deposition rate and good uniformity, is suitable for a variety of materials, and the deposited film has high density, uniformity and low defect density, and high-quality films can usually be obtained. However, up to now, there is no mature method for preparing CrSb2 thin films using magnetron sputtering. Therefore, exploring and developing methods for preparing antiferromagnetic CrSb2 single crystal thin films using magnetron sputtering technology is of vital importance to promote the development of low-power and high-efficiency spintronic components, which has become one of the key issues to be solved in the current fields of materials science and electronics. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing an antiferromagnetic CrSb2 single crystal thin film, which can utilize magnetron sputtering technology to prepare the antiferromagnetic CrSb2 single crystal thin film.

[0005] In order to solve the above problems, the technical solution of the present invention is: A method for preparing an antiferromagnetic CrSb2 single crystal thin film comprises the following steps: Step 1, providing a single crystal substrate and a chromium-antimony alloy target; Step 2: placing the substrate in an ultra-high vacuum magnetron sputtering device, and heating the tray under vacuum conditions to make the substrate temperature reach a preset temperature; Step 3, introducing an inert gas at a preset temperature, and using a magnetron sputtering method to deposit a disordered chromium antimony compound film on the surface of the substrate; Step 4, maintaining the substrate temperature at a high temperature under vacuum to anneal the film; Step 5: Allow the substrate to cool naturally to room temperature under vacuum to obtain a CrSb2 single crystal thin film. Preferably, the substrate is a LaALO3 substrate. Preferably, the antiferromagnetic single crystal film is a CrSb2 film. Preferably, in step 2, the vacuum condition of the magnetron sputtering equipment is less than 10 -5 Pa, the substrate heating temperature is 480℃-520℃. Preferably, in step 3, the DC magnetron sputtering mode is adopted, the deposition temperature is 480°C - 520°C, the constant sputtering power is 60 - 120 w, the inert gas introduced is argon, its gas flow rate range is 30~60 sccm, the sputtering gas pressure range is 1.8~2.2 Pa, and the deposition time is 6 - 10 min. Preferably, in step 4, the annealing temperature is 480°C - 520°C, and the annealing time is 0.5 h - 1 h. Preferably, in step 4, the vacuum condition of the annealing chamber is less than 8*10 -4 Pa. Preferably, in step 5, the vacuum condition of the natural cooling chamber is less than 8*10 -4 Pa. Preferably, in step 5, the sample after annealing is transferred to a structure characterization device. Preferably, the morphology characterization device includes an X-ray diffractometer.

[0006] The beneficial effects of the present invention are as follows: 1. Preparation is carried out with the aid of a ultra-high vacuum interconnection system, which greatly avoids the contamination of impurities on the surface of the single-crystal thin film. By precisely controlling various parameters in the preparation process, such as in the substrate heating, sputtering deposition, and annealing processes, strictly controlling key factors such as vacuum degree, temperature, gas flow rate, and sputtering power, the defects and dislocation numbers inside the thin film are effectively reduced, and at the same time, the surface roughness is reduced. This enables the prepared CrSb2 single-crystal thin film to have high crystallinity integrity, providing a solid quality foundation for its application in the field of spintronics.

[0007] 2. The buffer layer used to eliminate lattice mismatch in the traditional process is abandoned, significantly simplifying the preparation process. At the same time, the subsequent annealing process is simple to operate, only requiring specific vacuum and temperature conditions, and no other complex gases need to be introduced except argon. This simple preparation method not only reduces production costs but also improves production efficiency, creating favorable conditions for large-scale industrial production. 3. The antiferromagnetic CrSb2 material itself has excellent robustness against charge and magnetic field perturbations. Combined with the high-quality thin film preparation technology of the present invention, spin electronics components with low power consumption, high performance, and strong anti-interference ability can be manufactured.

[0008] 4. The selected LaAlO3 substrate is highly compatible with the subsequent preparation process, greatly promoting the growth of the CrSb2 thin film. This enables the thin film to not only have excellent crystallization quality but also better integrate with modern micro-nano processing technology, providing strong support for the miniaturization and integration of devices. Description of the Drawings

[0009] The following further describes the present invention with reference to the drawings: Figure 1 This is the basic schematic diagram of the preparation of CrSb2 thin film by magnetron sputtering according to the present invention; Figure 2 This is the schematic diagram of the atomic structure of CrSb2 according to the present invention; Figure 3 This is the high-resolution X-ray diffraction schematic diagram of CrSb2 thin film when the sputtering power is 90W.

[0010] In the figure: tray 1, LaAlO3 substrate 2, CrSb2 thin film 3, gas inlet 4, chromium-antimony alloy target 5, target circulating cooling water 6, DC power supply 7, vacuum pumping port 8, high-magnetic target position 9, Cr atom 10, Sb atom 11. Specific embodiments

[0011] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. 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.

[0012] The ultra-high vacuum magnetron sputtering equipment used in this embodiment is a magnetron sputtering thin film 3 deposition system (PVD). The substrate 2 is a single-crystal LaAlO3 substrate 2, and the antiferromagnetic single-crystal thin film 3 is a CrSb2 thin film 3. The single-crystal LaAlO3 substrate 2 can be adapted to the subsequent preparation process, which is beneficial to the growth of the CrSb2 thin film 3 and enables the thin film 3 to have better crystallization quality and performance.

[0013] The preparation method of the CrSb2 single-crystal thin film 3 includes the following steps, as Figure 1 and 2 shown: S1: Ultrasonically clean the single-crystal LaAlO3 substrate 2 in acetone, ethanol, and deionized water to remove surface organic pollutants and adsorbed particulate matters, and prepare the chromium-antimony alloy target 5.

[0014] S2: Place the substrate 2 on the tray 1 in the magnetron sputtering thin film 3 deposition system, place the chromium-antimony alloy target 5 in the high-magnetic target position, turn on the target 5 circulating cooling water 6, heat the tray 1 after vacuum pumping, and then continue to pump vacuum to the vacuum condition required for thin film 3 deposition.

[0015] S3: Introduce the inert gas argon into the gas inlet 4 of the magnetron sputtering thin film 3 deposition system, and use magnetron sputtering to deposit a disordered chromium-antimony compound thin film 3 on the surface of the substrate 2.

[0016] S4: After deposition, keep the temperature of the substrate 2 at a high temperature in vacuum to anneal the thin film 3.

[0017] S5: After the annealing is completed, turn off the heating and wait for the substrate 2 to cool to room temperature under vacuum conditions to obtain the CrSb2 single crystal thin film 3.

[0018] S6: Use an X-ray diffractometer to detect the CrSb2 thin film 3 to obtain a high-resolution X-ray diffraction pattern. Detect the crystal phase structure of the thin film 3 through the X-ray diffractometer to determine whether it is the target CrSb2 thin film 3. As Figure 3 shown, X1 and X2 are the diffraction peaks of CrSb2, and Y1 and Y2 are the diffraction peaks of LaAlO3.

[0019] This preparation method of the CrSb2 single crystal thin film 3 of the present invention can be carried out in an ultra-high vacuum interconnection system, effectively avoiding the pollution of impurities on the surface of the single crystal thin film 3. At the same time, the defects, dislocations and surface roughness in the thin film 3 are minimized. In addition, this method is simple to operate and lays a foundation for subsequent production.

[0020] In step S2, the vacuum condition for the substrate 2 to be heated is 8×10 -4 Pa; the heating temperature of the tray 1 of the substrate 2 is 500°C; the vacuum deposition condition is 8×10 -4 Pa. Under this vacuum and temperature condition, it can provide a good environment for heating the substrate 2 and subsequent processes such as sputtering and annealing, contribute to the diffusion of atoms and the crystallization of the thin film 3, reduce the incorporation of impurities, and improve the quality of the thin film 3.

[0021] In step S3, adjust the argon gas flow rate to 60 sccm, the chamber pressure during sputtering is 2 Pa, the sputtering power of the DC power supply 7 is 90 w, and the sputtering time is 6 min; the setting of these parameters can accurately control the growth rate, composition and structure of the thin film 3, ensure that the formed disordered chromium antimonide compound thin film 3 has good uniformity and low defect density, and is beneficial to the subsequent formation of a high-quality CrSb2 single crystal thin film 3.

[0022] In step S4, continue to evacuate to 8×10 -4 Pa, keep the heating tray 1 on, and keep the temperature of the substrate 2 at 500° for annealing for 1 h. Within this annealing temperature and time range, it can effectively eliminate the internal stress of the thin film 3, promote the orderly arrangement of atoms, improve the crystallinity and quality of the thin film 3, and improve the performance of the thin film 3. In step S5, the vacuum condition is less than 8×10 -4 Pa, and the cooling rate is 20 - 50 °C / min. Natural cooling under vacuum environment can prevent foreign impurities from adsorbing on the surface of the thin film 3 during the cooling process, maintain the purity of the thin film 3, and at the same time is beneficial to the stability of the internal structure of the thin film 3.

[0023] The content described in the embodiments of this specification is only an enumeration of the implementation forms of the inventive concept. The protection scope of the present invention should not be regarded as limited to the specific forms stated in the embodiments, and the protection scope of the present invention also extends to equivalent technical means that can be conceived by those skilled in the art according to the inventive concept of the present invention.

Claims

1. A method for preparing an antiferromagnetic CrSb2 single crystal thin film, characterized in that: The following steps are involved: Step 1, providing a single crystal substrate and a chromium-antimony alloy target; Step 2: placing the substrate in an ultra-high vacuum magnetron sputtering device, and heating the tray under vacuum conditions to make the substrate temperature reach a preset temperature; Step 3, introducing an inert gas at a preset temperature, and using a magnetron sputtering method to deposit a disordered chromium antimony compound film on the surface of the substrate; Step 4, maintaining the substrate temperature at a high temperature under vacuum to anneal the film; Step 5: Allow the substrate to cool naturally to room temperature under vacuum to obtain a CrSb2 single crystal thin film.

2. The method for preparing an antiferromagnetic CrSb2 single crystal thin film according to claim 1, characterized in that: The single crystal substrate is a LaAlO3 single crystal substrate.

3. The method for preparing an antiferromagnetic CrSb2 single crystal thin film according to claim 1, characterized in that: The antiferromagnetic single crystal film is a CrSb2 film.

4. The method for preparing an antiferromagnetic CrSb2 single crystal thin film according to claim 1, characterized in that: In step 2, the vacuum condition of the magnetron sputtering equipment is less than 10 -5 Pa, the substrate heating temperature is 480℃-520℃.

5. The method for preparing an antiferromagnetic CrSb2 single crystal thin film according to claim 1, characterized in that: In step 3, a DC magnetron sputtering mode is adopted, the deposition temperature is 480°C-520°C, the constant sputtering power is 60-120w, the inert gas introduced is argon, the gas flow range is 30-70sccm, the sputtering pressure range is 1.8~2.2Pa, and the deposition time is 6-10min.

6. The method for preparing an antiferromagnetic CrSb2 single crystal thin film according to claim 1, characterized in that: In step 4, the annealing temperature is 480° C.-520° C., and the annealing time is 0.5 h-1 h.

7. The method for preparing an antiferromagnetic CrSb2 single crystal thin film according to claim 1, characterized in that: In step 4, the vacuum condition of the annealing chamber is less than 8*10 -4 Pa.

8. The method for preparing an antiferromagnetic CrSb2 single crystal thin film according to claim 1, characterized in that: In step 5, the vacuum condition of the natural cooling chamber is less than 8*10 -4 Pa.

9. The method for preparing an antiferromagnetic CrSb2 single crystal thin film according to claim 1, characterized in that: In step 5, the annealed sample is transferred to a structural characterization device.

10. The method for preparing an antiferromagnetic CrSb2 single crystal thin film according to claim 9, characterized in that: The morphology characterization equipment includes an X-ray diffractometer.

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