|讲座人介绍||翟俊宜，男，于2001年7月和2004年 7月分获清华大学化学系学士学位和材料科学与工程系硕士学位。其后赴美留学，并于2009年2月获弗吉尼亚理工（Virginia Tech）材料科学与工程系博士学位。2009年4月翟俊宜博士获Director’s Postdoctoral Fellowship在洛斯阿拉莫斯国家实验室纳米中心做博士后研究。主要从事压电半导体材料的制备、外延功能氧化物生长和表征、新型多功能电子学和光电子器件设计与应用等方面的研究。至今已在Nature Nanotechnology、Advanced Materials、ACS Nano、 Applied Physics Letter等SCI杂志上发表了70篇材料方向的研究论文，引次数超过2500次，论文被引用的H因子(h-index)是30。已获得3个专利，参与重要国际会议报告共15次。2013年入选中组部青年千人计划。|
|讲座内容||Multifunctional micro/nano devices and systems are of important applications in smart electronics for health care, human-machine interfacing, infrastructure monitoring and security. In recent years, piezophototronic effect is developed fast since it offers a new method to improve/tune the optoelectronic properties dramatically. The key characteristic of the piezo-phototronic effect is that the carrier generation, transport, separation and/or recombination at the heterojunction/interface can be tuned by modulating the piezopotential which created and further tuned by externally applied strain. Therefore, one method to enhance piezo-phototronic effect is increasing piezoelectric charge at the interface. Another method to improve piezo-phototronic effect is reducing charge carrier recombination probability, the design of semiconductor composites heterojunction/interface should take into account their band positions and band gap. By interface engineering the p-n junction, piezo-phototronic effect can be improved.
Piezophototronic effect can enhance the sensitivity of photodetector dramatically. Here, we show a self-powered GaN flexible film-based metal-semiconductor-metal (MSM) UV photoswitch. The asymmetric MSM structure was designed to suppress carrier recombination and enhance carrier transport. At self-powered condition (no external bias voltage), its UV on/off ratio reaches up to 4.67*105 with high reliability of on/off switching response. Also its UV detection shows an excellent sensitivity (1.78*1012 cmHz0.5W-1). In particular, strain modulation can improve the UV on/off ratio (~154%) by piezo-phototronic effect.
Besides photoelectric conversion and electroluminescence, photoluminescence can be tuned by piezoelectric charge as well. Here have developed a new method of pressure sensing by using pressure/strain induced piezoelectric charge to tune PL intensity of InGaN/GaN MQW under small strain (0~0.15 %). Such modulation effect is distinct, linear and ultrafast. Based upon it, an all optical pressure sensor array by the piezo-phototronics effect has been developed to measure dynamic pressure distribution without the need of electricity. Beyond the limitations of electrical connection, our all-optical device offers a novel and suitable way for large-area, high-uniform, high resolution, ultrahigh speed pressure/strain distribution sensing.