Effective chemical potential for non-equilibrium systems and its application to molecular beam epitaxy of Bi₂Se<span style="font-size: 13.3333px;">₃</span>-学术交流-吉林大学超硬材料国家重点实验室

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Effective chemical potential for non-equilibrium systems and its application to molecular beam epitaxy of Bi₂Se

信息来源:本站 发布时间:2017-06-14

报告题目:Effective chemical potential for non-equilibrium systems and its application to molecular beam epitaxy of Bi2Se3

报告人:张绳百 教授

            美国伦斯勒理工学院

Abstract: First-principles studies often rely on the assumption of equilibrium, which can be a poor approximation, e.g., for growth. Here, we propose a general effective chemical potential (μ) approach for non-equilibrium systems. It incorporates growth kinetics into the chemical potential, while maintaining its correct equilibrium limits. In studying molecular beam epitaxy (MBE), we divide the process into three stages: pre-nucleation, nucleation, island growth, and focus our efforts on the first two. For the pre-nucleation stage, we solve the rate equations for small clusters on the surface, which serve as the feedstock for the growth, and find thatμ is determined by the most probable cluster. While this finding contradicts the equilibrium theory (which is in favor of the lowest-energy state), it reinforces the fundamental principle of statistic mechanics. In the case of Bi2Se3,μ is found to be highly supersaturated. Asμ determines the nucleation barrier for the nucleation stage, this supersaturation leads to a high nucleus concentration and small-sized islands, in qualitative agreement with experiment.

报告人简介:张绳百教授,吉大校友,国际著名半导体物理学家,美国物理学会会士,曾在Phys. Rev. Lett.上发表研究论文近60篇,美国伦斯勒理工学院Kodosky星座教授。1981年毕业于吉大电子系,1982年以全国第六名考取李政道先生主持的中美物理奖学金CUSPEA,1989年获加州大学伯克利分校博士学位,导师为Marvin L. Cohen。曾任美国再生能源国家实验室资深研究员。自2006年张教授受邀担任母校客座教授,曾指导吉大电子学院青年教师、学生在PRL, Nat. Comm., Nano Lett.等发表研究成果。

时间:2017年6月16日(周五)上午9:00

地点:前卫南区唐敖庆楼C区603报告厅

举办单位:超硬材料国家重点实验室

               物理学院

               吉林省物理学会

               中国物理学会高压物理专业委员会