报告人：Prof. Xiaobin Niu（University of Electronic Science and Technology of China (UESTC).

 摘要：

Strain induced self-assembly provides an attractive route to nanofabrication of semiconductor quantum dots on surfaces. Recent experiments have demonstrated that combining the strain induced self-assembly with surface patterning provides an effective method to further improve the size uniformity and spatial ordering of quantum dots. However, the underlying mechanisms responsible for such improvement remain poorly understood. In this talk, I will present theoretical analyses of strain induced growth instability and island nucleation on patterned substrates. We show that the growth of a strained film is inherently less stable on a wavy substrate than on a flat substrate. For small surface undulation, the critical wavelength characterizing the initial instability on a wavy substrate is effectively half of that on a flat substrate. Furthermore, on patterned substrates, island nucleation is directed to the preferred sites by a much lower energy barrier and smaller critical size. Strain relaxation directs island nucleation to the bottom of a pit rather than the top of a ridge as commonly perceived, while large surface energy anisotropy leads to nucleation at both places. Our theory explains some puzzling experimental results and provides useful guidelines for future exploration of directing the self-assembly of quantum dots on patterned substrates.

简介：

Xiaobin Niu received his B.S. and M.S. degree in Condensed Matter Physics from University of Science and Technology of China in 2000 and 2003. After that, he went to US and earned his Ph.D. degree in Materials Science and Engineering from University of California, Los Angeles in 2008. He was a postdoctoral Fellow in the Department of Materials Science and Engineering at University of Utah from 2008 to 2011 and in the Department of Mechanical Engineering at University of Connecticut from 2011 to 2013. Then he moved to Boston and became a Research Assistant Professor in the Department of Mechanical and Industrial Engineering at Northeastern University. Since 2014, he has been appointed as a Professor of National 1000-Talents-Young Program at University of Electronic Science and Technology of China (UESTC).

地点：中科院物理研究所M238会议室

联系人：许秀来 研究员 （Tel：82649820）

主办单位：中国科学院光物理重点实验室