基于磷烯类二维材料的纳米器件的热电和光电自旋输运性质研究

The spin Seebeck effect controlled by the temperature gradient can obtain the spin current, thus reducing the power dissipation caused by charge. In addition, light excitation can also generate spin-current, which is widely used in the optical communication combined by the green solar cell technique and the fast and low-energy spintronics. But finding thermoelectric materials and photoelectric materials that produce net spin is still a challenge. Phosphorene analogue two-dimensional materials, such as black phosphorene, blue phosphorene and SnX (X= S, Se, Te), GeX (X= S, Se, Te), etc., are a class of new semiconductor materials. Their greatest advantage is that they have intrinsic energy gaps. In this project, we will apply density functional theory combined with nonequilibrium Green's function method, to construct single-layer and double-layer structure configuration based on phosphorene analogue two-dimensional materials through effective way, combined with the doping or adsorption, even rolling them into the nanotubes, meanwhile, applying the stress and electric field, to design the heat and light multifunctional electronic devices, discussing the effect of the edge passivating way, nanoribbon width and the atom doping or adsorption on the semiconducting feature, electromagnetic peculiarity and transport property, then researching the effect of temperature gradient, mechanical strain, illumination of the polarized lights, along with the electric field, on the spin transport properties, analyzing the mechanism of quantum transport, and then exploring the new applications of these materials in the field of quantum transport and optical communication.

由温度梯度调控的自旋塞贝克效应可以得到净的自旋电流，从而降低由电荷引起的功耗。另外，光激发也能产生自旋电流，由绿色环保的太阳能电池技术和快速低能耗的自旋电子学相结合的光通信有广泛的应用。但是找到能产生净自旋流的热电和光电材料目前还是一个挑战。磷烯类二维材料，如黑磷烯、蓝磷烯和SnX (X= S, Se, Te), GeX (X= S, Se, Te)等是一类新型半导体材料，其最大的优点在于具有本征能隙。本项目采用密度泛函理论结合非平衡态格林函数的方法，把此类材料通过有效的方式复合和堆积，以及掺杂或者吸附，甚至卷成纳米管，并且施加应力以及电场，设计基于磷烯类材料的多功能的热和光电子学器件，讨论边缘钝化方式、纳米带宽度和原子掺杂及吸附对结构的半导体性、电磁性质、输运性质等的调控，研究温度梯度、力学应变、光场和电场对自旋输运性质的影响，分析量子输运机理，探索这类材料在量子输运和光通讯方面的应用。

电子学和自旋电子学是正在发展中的前沿学科，在纳米科学等领域有着重要的应用前景。由温度梯度调控的自旋塞贝克效应可以得到净的自旋电流，从而降低由电荷流引起的功耗。另外，光激发也能产生自旋电流，由绿色环保的太阳能电池技术和快速低能耗的自旋电子学相结合的光通信有广泛的应用。本项目采用密度泛函理论（DFT）与非平衡态格林函数（NEGF）相结合的方法，研究了锯齿型石墨烯纳米带在不同电场调控下的热电自旋输运性质，以及α-Te烯和FeAsS的电子结构和热电转换性能。此外，还研究发现通过非金属Cl层间掺杂双层砷烯可以实现高密度非易失电控存储。并且研究了不同直径和不同手性的蓝磷纳米管在铁磁钴电极自旋注入后的自旋光电效应。进一步研究发现，当用被Cl吸附的黑磷烯做电极时，因其具有双极性的自旋半导体特性，得到了纯自旋光电流。纯自旋光电流可以减少电子之间的相互作用，从而降低器件的焦耳热。另外通过对范德瓦尔斯异质结FeCl2/WSe2/FeCl2的自旋输运性质研究发现，用半金属材料做电极可以增强器件的巨磁阻效应，为提高巨磁阻效应指出了新方向。本项目的研究结果拓宽了磷烯类二维材料在多领域的应用，为实验上制备基于磷烯新材料的热自旋电子学器件和光电器件提供理论指导。