层状半导体电输运性质的第一性原理研究

Layered semiconductors have shown great promise for the wide applications of nanoelectronic and thermoelectrical devices, which usually require layered semiconductors to have high carrier mobility. So far, ideal layered semiconductors with high mobility and stability are yet to be found and designed. The key issues to solve the problem are to theoretically predict the intrinsic carrier mobility of a large variety of layered semiconductors fast and accurately, and to reveal the key factors and underlying physical mechanisms that determine mobility. This project is devoted to developing a new method by considering the scattering of electrons by acoustic and optical phonons, with the aim to calculate the intrinsic carrier mobility of a large variety of layered materials with proper cost and accuracy. The critical factors that control the electrical transport properties of layered semiconductors and the underlying physical mechanisms will be revealed through systematical studies. Based on the above studies, possible candidates of layered semiconductors with high mobility will be screened out from available material data base with the help of high-throughput calculations. In addition, inverse design methods will also be used to find layered materials with high mobility. This project is of great importance for the understanding of the electrical transport properties of layered materials, and will be helpful for the large-scale practical applications of layered semiconductor devices.

层状半导体在微纳电子器件和热电转换器件等领域具有广泛的应用前景，这些应用通常要求半导体具有高载流子迁移率。目前，理想的高迁移率高稳定性层状半导体有待寻找和设计。为此，能够在理论上快速而准确的预测大量层状半导体载流子本征迁移率，揭示决定迁移率的关键因素和物理机制，是解决问题的关键。本项目拟从第一性原理方法出发，综合考虑电子受到声子声学支和光学支的散射，发展计算载流子本征迁移率的新算法，能够以合适的计算代价准确的计算大量层状半导体的本征迁移率。通过系统研究各种因素对层状半导体迁移率的影响，揭示控制层状半导体电输运能力的关键因素和相应的物理机制。在此基础上，利用高通量计算方法，从材料数据库中搜寻高载流子迁移率层状半导体；通过材料逆向设计思想和方法，设计高迁移率层状半导体。本项目的研究有助于理解层状半导体的电输运物性和推进层状半导体器件的大规模应用。

层状半导体在微纳器件领域具有广泛的应用前景，但是这些应用通常要求半导体具有高载流子迁移率。目前研究较多的体系包括单层黑磷和过渡金属硫族化合物等，它们的迁移率最高只有几百cm2V-1s-1， 远低于三维的晶体硅和GaAs体系，理想的高迁移率层状半导体仍然有待寻找和设计。然而，在理论上准确计算迁移率需要全面考虑电声耦合作用，计算成本高昂。为此，发展能够快速而准确预测层状半导体载流子本征迁移率的方法，揭示决定迁移率高低的关键因素和物理机制，是解决问题的关键。本项目基于第一性原理，综合考虑电子受到声子声学支和光学支的散射，发展了基于声子谱能量分辨的载流子散射机制分析方法，进而以模型系统推导出决定散射几率的基本物理图像，提出了快速筛选高迁移率体系的基本规则。利用高通量方法，我们系统筛选了传统半导体的二维单层体系，预言了若干迁移率接近或者超过1000 cm2V-1s-1的二维半导体体系。本项目的研究有助于理解层状半导体的电输运物性和推进层状半导体器件的大规模应用。