Strongly Facet-Dependent Properties of Semiconductor Crystals
讲座名称：
Strongly Facet-Dependent Properties of Semiconductor Crystals
讲座时间：
2018-04-02
讲座人：
黄暄益
形式：
校区：
兴庆校区
实践学分：
讲座内容：
讲座题目：Strongly Facet-Dependent Properties of Semiconductor Crystals
讲座时间：2018年4月2日下午15:00-16:00
讲座地点：仲英大楼B253
讲座人：黄暄益 台湾清华大学化学系教授
讲座摘要：
From our years of research to synthesize metal and semiconductor nanocrystals with systematic shape control, the crystals have allowed us to examine their facet-dependent catalytic properties. We now also have a good understanding of factors controlling the particle shapes for crystals formed by redox reactions and precipitation reactions. From our studies on the various properties of Cu2O and other semiconductor crystals, we have discovered that they possess strongly facet-dependent photocatalytic activity, electrical conductivity, and light absorption properties. We come to understand through DFT calculations that all these phenomena can be explained due to the presence of an ultrathin surface layer with different band structures for different crystal faces ({100}, {110}, and {111}) and hence different degrees of band bending and barriers to semiconductor charge carrier transport. Recently we have shown that Si wafers also possess facet-dependent electrical conductivity properties that can be used to design new transistors. And semiconductor interfacial charge transfer is also strongly facet-dependent. We discovered that semiconductor materials possess facet-dependent optical properties also because of the presence of this thin layer, and has constructed a modified band diagram to explain the observations. Thus we have fundamentally changed current understanding of semiconductor materials. This is our main contribution. Review articles have been published to spread this knowledge. Of course, we also have efforts in supercrystal formation and facet-dependent organocatalysis.
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