CrN/GaN异质结构的磁性和电输运性质研究

The dilute magnetic semiconductors formed by doping magnetic ions or non-magnetic ions or other defects into semiconductors can take advantages of both charge property and spin property of the electrons, among which the CrN-based magnetic semiconductor have the antiferromagnetism with an orthorhombic crystalline structure or room temperature ferromagnetism induced by the defects. The detail study on interface magnetism and electrical transport of CrN/GaN magnetic semiconductor heterostructures will has great contributions to understand the magnetism origin, magnetic couplings between carriers and Cr spins and the control of ferromagnetism. This research will lay a foundation for spin injection and transport. In this project, the materials growth and physical properties including the magnetic and electrical properties related to the spins in CrN magnetic material and CrN/GaN multilayers will be focused. The interface microstructure, electronic structure, local moments and tunnelling effects in the CrN/GaN heterostructures will be studied also. In addition, the control of ferromagnetism in CrN and spin injection to GaN will be investigated to gain the interaction relation between the interface magnetism and carries transport. Investigate the physical mechanisms underlying magnetisms of the CrN/GaN heterostructures, combined with the research of the compulation based the fist-principle theory.

在半导体中掺入磁性元素或非磁性元素或引入其他缺陷可以形成磁性半导体，磁性半导体可同时利用电子的电荷属性和自旋属性；其中CrN基磁性半导体具有正交结构反铁磁性和缺陷诱导的铁磁性。对CrN/GaN异质结构中界面磁性和电输运行为的深入研究，有助于阐明本征缺陷对磁性的调控行为；获得界面磁性耦合规律，为解决自旋注入与载流子输运等基本科学问题提供依据。本项目将主要研究磁性材料CrN及其异质结构的生长制备和与自旋相关的磁学和电学性质；CrN/GaN多层异质结构的界面微观结构、电子结构、局域磁矩和隧穿效应等物理性质；异质结构界面极化载流子从CrN向GaN的注入与输运，获得界面磁性和电输运的关系。结合基于第一性原理的理论计算，探索磁性异质结构磁性耦合的物理本质。

在传统半导体中掺入金属元素或非金属元素形可成磁性半导体；磁性半导体可同时利用电子的电荷属性和自旋属性。本项目结合申请人在单晶薄膜外延制备、磁性研究和第一性原理计算方面的研究基础，提出通过对CrN/GaN异质结构中界面磁性和电输运行为的深入研究，阐明本征缺陷对磁性的调控行为，获得磁性耦合规律。我们研究了Cr掺杂的GaN、InN外延薄膜的制备条件，成功实现替位掺杂并制备出具有较高晶体质量的具有室温铁磁性的外延单晶薄膜。我们研究了Cr掺杂、Si掺杂对GaN及GaCrN外延薄膜的晶体质量、铁磁性的影响；结合第一性原理模拟计算分析了掺杂对GaN外延薄膜系统铁磁性的调制。由于设备的原因，我们放弃了CrN(111)/GaN(0002)/CrN(111)体系界面局域磁矩的研究，同时转向制备较为容易的TiO2纳米管系统，并研究其纳米管壁的表面缺陷与纳米管间界面局域磁矩。我们采用阳极氧化法分别制备了Mn、Fe、Cu、Ru、Au和N共掺杂的TiO2纳米管阵列，测得这些样品均具有室温铁磁性，结合第一性原理计算分析了氧空位存在时，金属、非金属、及两者掺杂对晶胞磁矩的调制，系统研究了掺杂杂质和氧空位对该纳米管系统室温铁磁性及载流子特性的影响。