Method for enhancing magnetism of Y-doped HfO2 diluted magnetic semiconductor film through gamma ray induction

Abstract

The invention belongs to the technical field of diluted magnetic semiconductor films, and particularly discloses a method for enhancing the magnetism of a Y-doped HfO2 diluted magnetic semiconductor film through gamma ray induction, and the method comprises the following steps: S1, placing a Y-doped HfO2 target material in a radio frequency device, fixing a 111-oriented YSZ substrate at the central position of a dial plate of the radio frequency device, and enabling the target material to correspond to the substrate; s2, turning on a radio frequency power supply, and officially sputtering after glow is stable to obtain a thin film; s3, annealing the film in a muffle furnace; and S4, placing the annealed film sample in a gamma ray device with 60Co as an irradiation source for irradiation to realize total ion implantation dose treatment. According to the method for enhancing the magnetism of the Y-doped HfO2 diluted magnetic semiconductor thin film through gamma ray induction, the problem that the saturation magnetization intensity of an existing diluted magnetic semiconductor thin film is not high is solved, and the magnetism of the Y-doped HfO2 epitaxial thin film is enhanced, regulated and controlled through gamma ray micro dose.

Description

Technical Field

[0001] This invention relates to the field of dilute magnetic semiconductor thin film technology, and in particular to a method for enhancing the magnetism of Y-doped HfO2 dilute magnetic semiconductor thin films by γ-ray induction. Background Technology

[0002] Spintronics (also known as magnetoelectronics) utilizes electron spin and magnetic moments for information storage and computation. Because the energy required to change the spin state is far less than that required for charge transport, spin devices outperform traditional microelectronic devices in terms of speed, power consumption, and heat generation. As a key material in spintronics, dilute magnetic semiconductors (DMS) have achieved room-temperature ferromagnetism in group II-VI, group III-V, or metal oxide systems by doping with transition metals or introducing point defects, providing a material basis for devices such as spin valves, magnetic tunnel junctions, magnetic sensors, and spin LEDs. In recent years, HfO2-based thin films have attracted widespread attention due to their high compatibility with CMOS processes, high dielectric constant, and ability to achieve ferroelectricity even at nanometer thicknesses. More importantly, research has found that Y-doped or defect-tuned HfO2 thin films can also exhibit "d" characteristics. o "Its ferromagnetic or multiferroic properties make it a new type of dilute magnetic semiconductor."

[0003] Qi et al. prepared HfO2 films of varying thicknesses on PPA substrates using DC magnetron sputtering. Hysteresis loop results showed that all HfO2 films exhibited significant ferromagnetism at room temperature, which they attributed to oxygen vacancies. Low- or medium-energy ion implantation by Chen et al. has been used for PbZrO3 and HfO2 films. 0.5 Zr 0.5 In O2 and other thin films, polarized nanoregions or defects can be introduced to significantly improve energy storage density or ferroelectric fatigue life. For hafnium-based devices, tolerance to total ion dose (TID) irradiation is of particular concern: for example, 3 MeV protons (5 × 10⁻⁶ ions / day). 13 -1×10 15 ions / cm 2 Studies on the ferroelectric capacitance of Y-doped HfO2 show that its ferroelectric loop and dielectric constant exhibit only slight attenuation, demonstrating excellent irradiation stability. Sharma et al. prepared Ni-doped HfO2 films by low-energy Ni ion implantation, and used Ni... 3+ Ion irradiation was applied to these thin films to uniformly disperse and activate the injected Ni ions. Hysteresis loop results showed that the saturation magnetization increased with increasing radiation dose, due to the generation of defects such as oxygen vacancies caused by the dispersion and activation of the injected Ni ions. Gamma rays (high-energy photons) were also applied to HfO. xGamma rays have been used in RRAM to study the stability of resistive switches and conductive filaments, with a total dose reaching 5.2 Mrad (Si). After irradiation, the device function is basically maintained, but the stability of the filaments decreases. However, there are no publicly available reports on the magnetic modulation of Y-doped HfO2 thin films by micro-dose gamma rays.

[0004] Currently, existing irradiation research focuses on electrical / ferroelectric properties; research on magnetism remains scarce. Y-doped HfO2 exhibits weak ferromagnetism at room temperature without the addition of external magnetic ions, but its saturation magnetization is typically around 10 emu / cm. 3 It is located nearby and lacks controllable amplification methods. Summary of the Invention

[0005] The purpose of this invention is to provide a method for enhancing the magnetism of Y-doped HfO2 dilute magnetic semiconductor thin films by inducing gamma rays, thereby improving the problem of low saturation magnetization in current dilute magnetic semiconductor thin films. This method enhances and modulates the magnetism of Y-doped HfO2 epitaxial thin films by using micro-dose gamma rays.

[0006] To achieve the above objectives, the present invention provides a method for enhancing the magnetism of Y-doped HfO2 dilute magnetic semiconductor thin films by γ-ray induction, comprising the following steps: S1, HfO2 doped with Y 0.93 Y 0.07 The O2 target is placed at the corresponding RF target position of the RF device, and the 111-oriented YSZ substrate is fixed to the center of the RF device dial using high-temperature tape, so that the target and the substrate correspond to each other. S2. Turn on the RF power supply, and after confirming that the glow discharge is stable, begin the sputtering process. Set the sputtering time to 10 minutes, and sputtering at room temperature will yield Hf. 0.93 Y 0.07 O2 thin film; S3, Hf 0.93 Y 0.07 O2 film annealed in muffle furnace; S4. Anneal the Hf 0.93 Y 0.07 O2 thin film sample placed 60 Irradiation is performed in a gamma-ray device with Co as the irradiation source to achieve total ion implantation dose treatment.

[0007] Preferably, in step S1, the distance between the target and the substrate is 90 mm, and the vacuum degree of the RF device is set to ≤2×10⁻⁶. - 4 Pa, introduce 30 sccm of Ar gas to control the gas pressure at 1.3 Pa.

[0008] Preferably, in step S, the RF power supply is adjusted to 60W, pre-sputtering is performed for 10 minutes, and the dial rotation speed is set to 10 r / min.

[0009] Preferably, in step S3, the annealing is carried out in a muffle furnace for 1200 min, the heating time is 200 min, and the annealing temperature is 800℃.

[0010] Preferably, in step S4, irradiation is performed at a dose rate of 50 rad / s at room temperature, and the total irradiation dose is 260 Gy.

[0011] The advantages and beneficial effects of the method for enhancing the magnetism of Y-doped HfO2 dilute magnetic semiconductor thin films by γ-ray induction as described above are as follows: 1. This invention utilizes radio frequency magnetron sputtering to directly deposit Hf on a YSZ substrate. 0.93 Y 0.07 O2 dilute magnetic semiconductor thin films exhibit excellent crystallinity after irradiation treatment.

[0012] 2. The Hf prepared by this invention 0.93 Y 0.07 The room-temperature ferromagnetism of O2 dilute magnetic semiconductor thin films was measured using a vibrating sample magnetometer (VSM). By varying the irradiation dose, the room-temperature ferromagnetism of the films was significantly improved; the out-of-plane saturation magnetization of the unirradiated film was 36 emu / cm. 3 After irradiation with a dose of 260 Gy, its out-of-plane saturation magnetization increased to 69 emu / cm. 3 An increase of 91.6%.

[0013] 3. The Hf prepared by this invention 0.93 Y 0.07 O2 dilute magnetic semiconductor thin films exhibit significant magnetic anisotropy. The percentage value of magnetic anisotropy is defined as (out-of-plane saturation magnetization - in-plane saturation magnetization) / in-plane saturation magnetization, which is used to determine the strength of the magnetic anisotropy; the higher the percentage value, the stronger the magnetic anisotropy. The out-of-plane and in-plane saturation magnetizations of a 13nm thick unirradiated film are 36 emu / cm. 3 20 emu / cm 3 Its magnetic anisotropy percentage is 80%. Irradiation can significantly improve its magnetic anisotropy; after irradiation with a dose of 260 Gy, its out-of-plane and in-plane saturation magnetization are 69 emu / cm², respectively. 3 21emu / cm 3 Based on the above, its magnetic anisotropy percentage is 228%.

[0014] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0015] Figure 1The present invention is based on 0 Gy and 260 Gy Hf irradiation. 0.93 Y 0.07 XRD diffraction pattern of O2 (including annealing at 800℃) dilute magnetic semiconductor thin film; Figure 2 The present invention is based on 0 Gy and 260 Gy Hf irradiation. 0.93 Y 0.07 In-plane MH hysteresis loop of O2 (including annealing at 800℃) dilute magnetic semiconductor thin film; Figure 3 The present invention is based on 0 Gy and 260 Gy Hf irradiation. 0.93 Y 0.07 Out-of-plane MH hysteresis loop of O2 (including annealing at 800℃) dilute magnetic semiconductor thin film; Figure 4 The present invention is based on 0 Gy and 260 Gy Hf irradiation. 0.93 Y 0.07 The percentage of magnetic anisotropy in O2 dilute magnetic semiconductor thin films (including those annealed at 800℃). Detailed Implementation

[0016] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0018] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. Experimental instruments, equipment, and reagents in the following embodiments that do not specify their sources are all commercially available materials.

[0019] Unless otherwise defined or stated, all technical and scientific terms used in this invention have the same meaning as those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein can be applied to the methods of this invention. It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0020] Example 1 A method for enhancing the magnetism of Y-doped HfO2 dilute magnetic semiconductor thin films by inducing gamma rays includes the following steps: S1, HfO2 doped with Y 0.93 Y 0.07The O2 target is placed at the corresponding RF target position in the RF device. A 111-oriented YSZ substrate is fixed to the center of the RF device's dial using high-temperature tape, ensuring the target and substrate are aligned. The distance between the target and substrate is 90mm. The vacuum level of the RF device is set to ≤2×10⁻⁶. -4 Pa, introduce 30 sccm of Ar gas to control the gas pressure at 1.3 Pa.

[0021] S2. Turn on the RF power supply and adjust the RF power to 60W. Pre-sputter for 10 minutes, set the dial rotation speed to 10 r / min, and after confirming glow discharge stabilization, perform formal sputtering. Set the sputtering time to 10 minutes. Sputtering at room temperature will yield Hf. 0.93 Y 0.07 O2 thin film.

[0022] S3, Hf 0.93 Y 0.07 The O2 film was annealed in a muffle furnace for 1200 min, with a heating time of 200 min and an annealing temperature of 800℃.

[0023] S4. Anneal the Hf 0.93 Y 0.07 O2 thin film sample placed 60 A gamma-ray device using Co as the irradiation source irradiates at a dose rate of 50 rad / s at room temperature, achieving a total irradiation dose of 260 Gy, thus realizing total ion implantation dose treatment.

[0024] Example 2 10 nm thick Hf was prepared by radio frequency magnetron sputtering. 0.93 Y 0.07 O2 dilute magnetic semiconductor thin film. The specific steps are as follows: (1) Fix a 2-inch diameter 7% Y-doped HfO2 ceramic target at the RF target position of the RF device. Before preparing the thin film, clean the dial of the RF device with sandpaper. Use heat-resistant tape to fix the 111 oriented YSZ (yttrium stabilized zirconium oxide) substrate in the center of the dial. The distance between the target and the substrate is set to 90 mm.

[0025] (2) Close the vacuum chamber door of the radio frequency device and evacuate the vacuum level to ≤2×10 -4 Pa, introduce 30 sccm of Ar gas to control the gas pressure at 1.3 Pa.

[0026] (3) Turn on the RF power supply, adjust the power to 60W, set the dial speed to 10r / min, pre-sputter for 10min, and after confirming glow discharge stability, perform formal sputtering. Sputtering at room temperature for 10min will yield Hf. 0.93 Y 0.07 O2 dilute magnetic semiconductor thin film.

[0027] (4) The film with a sputtering time of 10 min is annealed in a muffle furnace for 1200 min, with a heating time of 200 min and an annealing temperature of 800℃.

[0028] (5) Annealed Hf 0.93 Y 0.07 O2 thin film sample placed 60 In a gamma-ray device using Co as the irradiation source, irradiation was carried out at a dose rate of 50 rad / s at room temperature, with a total irradiation dose of 260 Gy, achieving total ion implantation dose treatment.

[0029] Figure 1 The present invention is based on 0 Gy and 260 Gy Hf irradiation. 0.93 Y 0.07 XRD diffraction pattern of O2 (including annealing at 800℃) dilute magnetic semiconductor thin film.

[0030] like Figure 2 and Figure 3 As shown, 260 Gy of γ-ray irradiation can significantly enhance magnetic anisotropy and room-temperature ferromagnetism.

[0031] Figure 4 The present invention is based on 0 Gy and 260 Gy Hf irradiation. 0.93 Y 0.07 The percentage of magnetic anisotropy in O2 dilute magnetic semiconductor thin films (including those annealed at 800℃).

[0032] Hf can be directly deposited on YSZ substrates using radio frequency magnetron sputtering. 0.93 Y 0.07 O2 dilute magnetic semiconductor thin films exhibit excellent crystallinity after irradiation treatment.

[0033] The Hf prepared by this invention 0.93 Y 0.07 The room-temperature ferromagnetism of O2 dilute magnetic semiconductor thin films was measured using VSM. By varying the irradiation dose, the room-temperature ferromagnetism of the films could be significantly improved. The out-of-plane saturation magnetization of the unirradiated film was 36 emu / cm. 3 After irradiation with a dose of 260 Gy, its out-of-plane saturation magnetization increased to 69 emu / cm. 3 .

[0034] The Hf prepared by this invention 0.93 Y 0.07O2 dilute magnetic semiconductor thin films exhibit significant magnetic anisotropy. The percentage value of magnetic anisotropy is defined as (out-of-plane saturation magnetization - in-plane saturation magnetization) / in-plane saturation magnetization, which is used to determine the strength of the magnetic anisotropy; the higher the percentage value, the stronger the magnetic anisotropy. The out-of-plane and in-plane saturation magnetizations of a 13nm thick unirradiated film are 36 emu / cm. 3 20 emu / cm 3 Its magnetic anisotropy percentage is 80%. Irradiation can significantly improve its magnetic anisotropy; after irradiation with a dose of 260 Gy, its out-of-plane and in-plane saturation magnetization are 69 emu / cm², respectively. 3 21emu / cm 3 Based on the above, its magnetic anisotropy percentage is 228%.

[0035] Therefore, the present invention adopts the above-mentioned method of γ-ray induced enhancement of the magnetism of Y-doped HfO2 dilute magnetic semiconductor thin films to improve the problem of low saturation magnetization in current dilute magnetic semiconductor thin films, and enhances and controls the magnetism of Y-doped HfO2 epitaxial thin films by micro-dose of γ-rays.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for enhancing the magnetism of Y-doped HfO2 dilute magnetic semiconductor thin films by inducing gamma rays, characterized in that, Includes the following steps: S1, HfO2 doped with Y 0.93 Y 0.07 The O2 target is placed at the corresponding RF target position of the RF device, and the 111-oriented YSZ substrate is fixed to the center of the RF device dial using high-temperature tape, so that the target and the substrate correspond to each other. S2. Turn on the RF power supply, and after confirming that the glow discharge is stable, begin the sputtering process. Set the sputtering time to 10 minutes, and sputtering at room temperature will yield Hf. 0.93 Y 0.07 O2 thin film; S3, Hf 0.93 Y 0.07 O2 film annealed in muffle furnace; S4. Anneal the Hf 0.93 Y 0.07 O2 thin film sample placed 60 Irradiation is performed in a gamma-ray device with Co as the irradiation source to achieve total ion implantation dose treatment.

2. The method for enhancing the magnetism of Y-doped HfO2 dilute magnetic semiconductor thin films induced by γ-rays according to claim 1, characterized in that: In step S1, the distance between the target and the substrate is 90 mm, and the vacuum degree of the RF device is set to ≤2×10. -4 Pa, introduce 30 sccm of Ar gas to control the gas pressure at 1.3 Pa.

3. The method for enhancing the magnetism of Y-doped HfO2 dilute magnetic semiconductor thin films induced by γ-rays according to claim 1, characterized in that: In step S2, the RF power supply is adjusted to 60W, pre-sputtering is performed for 10 minutes, and the dial rotation speed is set to 10r / min.

4. The method for enhancing the magnetism of Y-doped HfO2 dilute magnetic semiconductor thin films induced by γ-rays according to claim 1, characterized in that: In step S3, the furnace is annealed for 1200 min in a muffle furnace, with a heating time of 200 min and an annealing temperature of 800℃.

5. The method for enhancing the magnetism of Y-doped HfO2 dilute magnetic semiconductor thin films induced by γ-rays according to claim 1, characterized in that: In step S4, irradiation is performed at a dose rate of 50 rad / s at room temperature, with a total irradiation dose of 260 Gy.

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