BiCuSeO系统单晶的本征电输运、热输运的物理机理研究

This project is to study the intrinsic electrical and thermal transport properties in stoichiometric and nonstoichiometric BiCuSeO and related BiCuS/Se/TeO single crystals. Stoichiometric and Nonstoichiometric BiCuSeO single crystals will be synthesized through controlling growth temperature carefully. By means of these samples, we will study their intrinsic electrical and thermal transport properties and related anisotropic properties. The electron energy gap, carrier effective mass, defect mechanism forming carrier and carrier scattering mechanisms will be studied in experiment. The defect structure and microstructure of these samples will also be studied by spectroscopy and transmission electron microscopy. Combining these experimental results, we will use electron and phonon dispersions obtained by the first principles calculation, as well as Kubo electron transport theory and Callway thermal transport theory to carefully study the scattering mechanism. And roles played by all kinds of scattering mechanims will be distinguished. Taking advantage of these information, we will propose and realize the program to optimize the electrical and thermal transport in BiCuSeO.

本项目拟研究具有层状结构的化学计量比与非化学计量比BiCuSeO及其系列的的氧族BiCuS/Se/TeO单晶样品的本征电输运、热输运性质。通过仔细调节生长温度制备出化学计量比与非化学计量比的BiCuSeO的系列单晶。利用这些样品详细研究该系统本征的电输运、热输运和相关的各向异性物理性能。通过实验研究这些材料的电子能隙、载流子有效质量、形成载流子的缺陷机制、载流子散射的主要机制和声子散射的主要机制。也将利用各种谱学、透射电子显微术细致分析这些样品的缺陷性质和微结构性质。结合上的实验结果，拟结合量子力学第一性原理计算该系统的电子结构与声子结构，通过线性响应理论的电输运Kubo理论和热输运的Callway理论深入分析各种散射机制所起的作用。总结出影响该系统中电输运、热输运的主要因素。提出并实验在该系统中优化电输运和热输运的方案。