报告题目：Exploring the Peculiar Physical Properties and Possible Applications of Semiconductor Nanowires

报 告 人：俞大鹏，北京大学物理学院

报告时间：11月15日（周四）16:00

报告地点：理科楼郑裕彤讲堂

报告摘要：Nanowires have been a top-five focused research topics in physics, and stimulated intensive interests world-wide. This lecture composes of two major parts. In the first part, I will give a brief summary of our pioneer and leading contributions to the world-wide nanowire research. (1). We are the pioneers to synthesize silicon nanowires from the bottom via a catalytic-directed growth of semiconductor nanowires, and enable the controllability in size, orientation, and superlattice/coreshell heterostructures of semiconductor nanowires. (2). We extended the concept of nanowire synthesis to a wide variety of metal oxide nanowires, leading to a world-wide following up of the breakthrough. (3). It is further demonstrated that the physical properties of the semiconductor nanowires can be modified/ via chemical doping, tuned by magnetic and strain fields, resulting in the nanowire p-n heterojunctions, diluted magnetic semiconductors, and strain sensors. (4).We are the first to provide the experimental evidence of quantum confinement effect in silicon nanowires. It is showed that the spin current of a single magnetite nanowire can be tuned via magnetic field (spin filter), and the thermal spin transfer torque effect was also evidenced in a nanowire spin-valve. (5). We are the few pioneers to explore the field emission properties of nanowire arrays, thanks to the sharp tiny tips of the nanowires showing abnormal large field enhancement factor. The possible applications of the nanowire networks in high efficiency flexible solar cells are also demonstrated. Above pioneer work has lead to a total reference/citations >10,000 times by colleagues world-wide, and an H index of 54. In the main second part, I will extend to show the advantage of both high spatial and energy resolution cathodoluminescence (CL) in characterization of the fine structures of the nanomaterials. In particularly, I will demonstrate that the high special resolution of the CL at ~ 5.5 K enable us to address the significant strain modulation of the optical emission and electronic structures of semiconductor nano/micro wires. In contrast, the high energy resolution of the CL makes it possible to “see” directly the resonant SPP modes that are confined to the metal nanocavity.