报告题目：HighPressure Synthesis and Characterization of BC8-Si
报告人：张海东
时间：2017年6月30日（星期五）10:00
地点：材料馆A325
报告摘要：
Large-volume, phase-pure synthesis of BC8 silicon(Ia¯3, cI16) has enabled bulk measurements of optical, electronic, and thermalproperties. Unlike previous reports that conclude BC8-Si is semimetallic, wedemonstrate that this phase is a direct band gap semiconductor with a verysmall energy gap and moderate carrier concentration and mobility at roomtemperature, based on far- and midinfrared optical spectroscopy,temperature-dependent electrical conductivity, Seebeck and heat capacitymeasurements. Samples exhibit a plasma wavelength near 11μm, indicatingpotential for infrared plasmonic applications. Thermal conductivity is reducedby 1–2 orders of magnitude depending on temperature as compared with thediamond cubic (DC-Si) phase. The electronic structure and dielectric propertiescan be reproduced by first-principles calculations with hybrid functionalsafter adjusting the level of exact Hartree–Fock (HF) exchange mixing. Theseresults clarify existing limited and controversial experimental data sets andab initio calculations.
个人简介：
张海东博士，1996年本科毕业于北京理工大学物理学专业，2007年博士毕业于佛罗里达大学物理学专业，2007年至今先后在内布拉斯加大学林肯分校、纽约州立大学布法罗分校、俄亥俄州立大学、卡内基研究院和乔治华盛顿大学从事博士后以及研究科学家工作。现为乔治华盛顿大学机械及航空工程系研究科学家。在Nature Communications,Physical Review Letters, Physical Review B等杂志上发表多篇研究论文。
