题 目：Engineering Electronic Properties of Thermoelectric Semiconductors
报告人：G. Jeffrey SNYDER 教授
单 位：美国西北大学
时 间：2023/11/14（周二） 9:00
地 点：海西院综合楼235会议室
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附简介：
G. Jeffrey Snyder教授，美国西北大学材料科学与工程学院终身教授，从事热电材料研究领域研究，在电子能带结构工程和热电性能微观结构工程方面研究成果丰富，在包括Science（4）、Nature（1）、Nature Materials（8）、Joule（6）在内的国际顶尖科学期刊上发表论文近900篇，被引用次数接近90,000次，h-index为135。
Thermoelectric semiconductors often have complex electronic properties yet they can be modeled with a simple effective mass model. Good thermoelectric materials require a high weighted mobility which serves as the electronic component to the thermoelectric quality factor that determines peak zT. Often complex band structures with multi-valley Fermi surfaces are associated with high weighted mobility. This complexity arises from orbital chemistry as well as structure. Band convergence combined with the physics of avoided crossings can also be used to explain the band structures and provide strategies for band engineering Half Heusler materials.
Many thermoelectric materials such as Bi2Te3 are topological insulators (TI). The correlation can be understood in that the band inversion that causes TI can lead to band warping that leads to high valley degeneracy and low transport mass. In some systems the Fermi surface pockets can be anisotropic and even non-ellipsoidal, such as the tubes of Fermi surface found in SrTiO3 and Pb and Ge Chalcogenides. Tubes or sheets of Fermi surface rather than ellipsoidal pockets leads to a density of states like 1D or 2D low dimensional materials. By engineering the orbital chemistry complex behavior and unusual properties can be devised even in 3D materials.