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CN-116564706-B - Magnetic semiconductor film and preparation method thereof

CN116564706BCN 116564706 BCN116564706 BCN 116564706BCN-116564706-B

Abstract

The invention provides a method for preparing a magnetic semiconductor film, which comprises the following steps of (1) placing a polycrystalline magnetic semiconductor target material into a film deposition chamber, (2) placing a K simple substance and a Mn simple substance which are taken as beam source materials into two beam source furnaces respectively, (3) cleaning a substrate, then mounting the cleaned substrate on a substrate table, (4) heating the substrate table and then heating the substrate, (5) controlling the air pressure of the film deposition chamber to be 6-100Pa through nonreactive gas, and then epitaxially growing the film on the substrate by utilizing a molecular beam auxiliary pulse laser deposition method, (6) after the film growth is completed, adjusting the air pressure of the film deposition chamber and cooling the substrate to obtain the magnetic semiconductor film (Ba 1‑x K x )(Zn 1‑y Mn y ) 2 As 2 , wherein x is more than or equal to 0.08 and less than or equal to 0.40, and y is more than or equal to 0.15.

Inventors

  • CAO LIXIN
  • CHEN HAOFENG
  • YANG XIN
  • HUANG ZHONGXUE
  • WANG RUI

Assignees

  • 中国科学院物理研究所

Dates

Publication Date
20260508
Application Date
20220127

Claims (10)

  1. 1. A method of preparing a magnetic semiconductor thin film comprising the steps of: (1) Placing a polycrystalline magnetic semiconductor target into a film deposition chamber; (2) Respectively placing a K simple substance and a Mn simple substance serving as beam source materials into two beam source furnaces; (3) Cleaning a substrate, and then mounting the cleaned substrate on a substrate table; (4) Then, heating the substrate table and thereby heating the substrate; (5) Controlling the air pressure of the film deposition chamber to be 6-100Pa through nonreactive gas, and then epitaxially growing a film on the substrate by using a molecular beam auxiliary pulse laser deposition method; (6) After the film growth is completed, the air pressure of the film deposition chamber is regulated and the substrate is cooled to obtain the magnetic semiconductor film (Ba 1-x K x )(Zn 1-y Mn y ) 2 As 2 , wherein x is more than 0.08 and less than or equal to 0.40, and y is more than 0.15 and less than or equal to 0.30).
  2. 2. The method of claim 1, wherein the polycrystalline magnetic semiconductor target has a composition represented by the formula Ba 1-m K m (Zn 1-n Mn n ) 2 As 2 , where 0.10≤m≤ 0.30,0.10≤n≤0.30.
  3. 3. The method of claim 1, wherein after step (3) and before step (4), the method further comprises the steps of: And vacuumizing the thin film deposition chamber to make the vacuum degree in the thin film deposition chamber higher than 1 multiplied by 10 -6 Pa.
  4. 4. The method of claim 1, wherein the heating of the substrate table in step (4) is performed by heating the temperature of the substrate to 500-550 ℃ at a ramp rate of 10-30 ℃ per minute.
  5. 5. The method of claim 1, wherein after step (4) and before step (5), the method further comprises the steps of: The substrate is blocked by a baffle plate, then the surface of the target material is treated by pulse laser, wherein the number of pulses is 600-1200, and two beam source furnaces are heated.
  6. 6. The method of claim 5, wherein the heating of the two beam source furnaces is performed by heating the temperature of the beam source furnace charged with the elemental K to 100-300 ℃ and the temperature of the beam source furnace charged with the elemental Mn to 600-950 ℃.
  7. 7. The method of claim 1, wherein the substrate is selected from a (001) oriented SrTiO 3 single crystal substrate, a (001) oriented Si single crystal substrate, a (001) oriented MgAl 2 O 4 single crystal substrate, or a (001) oriented (La 0.272 Sr 0.728 )(Al 0.648 Ta 0.352 )O 3 single crystal substrate.
  8. 8. The method according to claim 1, wherein the epitaxially growing film in the step (5) is performed under the condition that an energy density of the pulsed laser is 120-160mJ/mm 2 and a laser repetition rate is 1-5Hz.
  9. 9. The method of claim 1, wherein the non-reactive gas is selected from one or more of argon, helium, and nitrogen.
  10. 10. A magnetic semiconductor thin film produced by the method according to any one of claims 1 to 9, which has a composition represented by the following chemical formula (Ba 1-x K x )(Zn 1-y Mn y ) 2 As 2 ), wherein 0.08< x≤0.40, and 0.15< y≤0.30.

Description

Magnetic semiconductor film and preparation method thereof Technical Field The invention belongs to the field of magnetic semiconductors. In particular, the invention relates to a magnetic semiconductor film with spin doping and charge doping separated from each other and a preparation method thereof. Background Semiconductor thin films and magnetic thin films are two major types of base materials for modern information science and technology, wherein semiconductor thin films based on charge physical properties are the material base of integrated circuits, solid-state microwave and laser devices, etc., while magnetic thin films based on spin physical properties are the material base of information storage devices and spintronics devices. As semiconductor lithographic feature sizes continue to decrease so as to approach physical limits on the nanometer scale, it is becoming a challenge whether current state of the art systems developed based on the original physical effects can continue. Breakthrough in new materials including various quantum materials capable of quantum computation, and magnetic semiconductor materials having both semiconductor characteristics and magnetism themselves, has been actively pursued. With the development of information science and technology, there is a need for preparing thin film materials for research into the new material. The research of the magnetic semiconductor starts in the sixties of the 20 th century, and the concentrated magnetic semiconductor represented by sulfide of Eu and Cr, and the II-VI family diluted magnetic semiconductor, the III-V family diluted magnetic semiconductor and the diluted magnetic oxide caused by doping of magnetic elements are successively experienced, which are several typical material research stages. A common feature of the above-mentioned classes of magnetically dilute semiconductor materials is that the doping of the magnetic element itself introduces spin doping, which, while introducing magnetism into the material, inevitably also results in a change in the charge doping level of the material. It is believed that spin doping and charge doping in the material must be better compatible. In recent years, a brand new material research platform (Nat. Commun.2 (2011)) is provided for researching spin doping regulation and charge doping regulation in a material, wherein (Ba 1-xKx)(Zn1-yMny)2As2) polycrystal system is used for increasing paramagnetic-ferromagnetic transition temperature (Tc) to 230K (Chin. Sci. Bull.59,2524 (2014)) and the record of Curie temperature of 200K in (Ga, mn) As system is exceeded (Nano. Letters.11, 2584 (2011)). Currently, (Ba 1-xKx)(Zn1-yMny)2As2 film is prepared by Pulse Laser Deposition (PLD) method (AIP ADVANCE 7,045017 (2017)) the research is faced with the obstacle that Mn content is lower than or equal to 15%, K content is lower than or equal to 8%, low Mn doping concentration means that magnetic ion concentration is low and magnetic ion concentration will directly influence magnetism of sample, and low K doping concentration means low carrier concentration may influence ferromagnetism of sample, both of which are resulted in (Tc of Ba 1-xKx)(Zn1-yMny)2As2 film is lower than 10K and magnetization intensity is weak, which limit application prospect of (Ba 1-xKx)(Zn1-yMny)2As2 film greatly, how to regulate K, mn doping content and how to increase their content, thereby increasing Tc, becoming important and difficult point of (Ba 1-xKx)(Zn1-yMny)2As2 diluted magnetic semiconductor research). Therefore, a method capable of increasing the K and Mn contents in the (Ba 1-xKx)(Zn1-yMny)2As2 film) film is urgently needed. Disclosure of Invention The present invention is directed to a method for preparing a (Ba 1-xKx)(Zn1-yMny)2As2) thin film, which can increase the K and Mn contents in the thin film, thereby increasing the paramagnetic-ferromagnetic transition temperature (Tc) of the thin film. The above object of the present invention is achieved by the following technical solutions. In the context of the present invention, the deposition apparatus of the present invention may employ apparatus already disclosed in the prior art, such as the deposition apparatus disclosed in CN 202576547U. The thin film deposition equipment comprises a thin film deposition cavity, a target bracket, a substrate table, a laser entrance port, a beam source furnace interface and a laser entrance port, wherein the cavity is formed by the periphery of a cavity shell, the target bracket is arranged in the middle of the cavity and used for placing a target formed by a component A, the substrate table is arranged in the middle of the cavity and opposite to the target bracket, the laser entrance port is arranged on the side face of the cavity shell and obliquely opposite to the target bracket and used for entering laser to bombard the target on the target bracket to generate plasma plume, the beam source furnace interface is arranged on the sid