半金属ZnxFe3-xO4/半导体异质结构的界面调控和自旋注入研究

Manipulation of generation and transportation of spin-polarized current in magnetic/semiconductor based structures are crucial for achieving highly efficient spin injection, which provides more opportunities for exploring advanced spintronic devices with low energy consumption and high speed operation. In our proposal, we will tune the interface barrier height of ZnxFe3-xO4/semiconductor by controlling the substitution level of Zn2+, which avoid using an ultrathin insulating layer acting as a tunnel barrier between the magnetic materials and semiconductor. This work provides an alternative approach to tune the interface of the magnetic/semiconductor heterostructure. Furthermore, the physical properties on transportation of spin-polarized current in the interface of ZnxFe3-xO4/semiconductor will be investigated. Our goal of this study is to understand the transport mechanisms of spin-polarized currents under the condition of Schottky contact and ohmic contact. In addition, we will also investigate the transport behavior of spin-polarized current in the semiconductor channel, and reveal the interaction among the spin-polarized current, the spin coherence length and the channel width in the semiconductor channel. The implementation of our proposal is not only helpful for building mechanism of controlling spin injection and spin transport of spin-polarized current by interface and semiconductor channel, but also supplying a basis for realizing highly efficient spin injection from half metal into semiconductor.

操控磁性材料/半导体结构自旋极化电流的产生和输运是实现高效自旋注入的根本途径，为发展低能耗和高速度的新型自旋电子器件提供契机。对此，本项目拟设计一种自旋电子直接由半金属ZnxFe3-xO4向半导体注入的结构，通过调节Zn2+离子取代浓度调控界面势垒高度，避免了在磁性材料和半导体之间引入超薄势垒层，为磁性材料/半导体异质结构界面调控提供新思路。在此基础上，研究ZnxFe3-xO4/半导体界面物性对自旋极化电流的输运的影响，阐明肖特基接触和欧姆接触两种不同的注入机制下自旋极化电流在异质结构界面的输运特性和物理机制。另外，探索自旋极化电流在半导体沟道中的输运行为，揭示自旋极化电流、自旋相干长度与沟道宽度在半导体沟道中相互作用规律。本项目的开展有助于建立界面物性和半导体沟道对自旋注入和输运的调控，为实现自旋电子直接由半金属向半导体的高效注入提供基础。

磁性材料/半导体异质结构因能实现多功能集成，在半导体基的自旋电子器件方面具有潜在的应用价值，已成为信息功能材料领域的研究热点。其中有效地操控磁性材料/半导体结构自旋极化电流的产生和输运是实现高效自旋注入的根本途径。基于此，本项目设计了ZnxFe3-xO4/半导体异质结，目的使自旋极化载流子由磁性半金属层直接注入半导体层，避免引入界面势垒层而导致的自旋翻转散射的发生，为磁性材料/半导体异质结构的界面物性调控提供新的思路。.首先，我们沉积制备出磁性和电学性质宽范围可调的ZnxFe3-xO4磁性氧化物/半导体异质结，并对它们的和磁性、自旋进动和电输运特性进行了研究。这些结果为研究ZnxFe3-xO4/半导体的磁输运特性和器件的加工提供了保障。考虑到界面对铁磁/半导体的自旋输运特性具有重要的影响，我们研究了异质结的界面物性，得到Fe3O4和GaAs之间是肖特基接触,而Fe3O4和InAs (Si)之间是欧姆接触，Zn掺杂可以调控界面势垒高度。不同接触之间导致的物性差异进行比较，帮助理解界面对薄膜磁性及输运特性影响的复杂行为。最后，我们构筑铁磁/半导体和铁磁/金属异质结构横向自旋阀器件，研究了界面特性对磁输运和电输运的影响。本项目基于ZnxFe3-xO4和其他铁磁材料界面物性和自旋输运的研究，为磁性材料/半导体异质结构基自旋电子器件的研究和应用提供理论及实验依据。