时间:2018-10-23 14:35 来源:未知 作者:研究生科 点击:
2-D PIEZOELECTRIC SEMICONDUCTOR MATERIALS WITH COUPLING OF PIEZOELECTRIC AND SEMICONDUCTOR PROPERTIES FOR OPTOELECTRONIC DEVICES
Michael Gyan 博士生
: Piezoelectric effect has been widely used in electromechanical sensing, actuation and energy harvesting, which produces polarization charges under mechanical deformation in materials lacking inversion symmetry/center of symmetry or with polarization domains. Conventional piezoelectric materials such as PZT and PVDF are electrically insulating and hence not feasible for constructing functional electronics or optoelectronics. The effect of mechanically-induced polarization on electronic and optoelectronic processes of charge carriers in piezoelectric materials has therefore been long overlooked. Semiconductor materials such as ZnO, GaN and CdS with wurtzite or zinc blende structures also possess piezoelectric properties but are not as extensively utilized in piezoelectric sensors and actuators as PZT due to their relatively small piezoelectric coefficients. The coupling between piezoelectric polarization, semiconductor and it properties has resulted in both novel fundamental phenomenon and unprecedented device applications, paving way for an increasing research interests in the emerging field of piezotronics and piezo-phototronics.
The fundamental principle of piezotronics and piezo-phototronics lies in the fact that strain-induced polarization charges introduce at interface can effectively regulate the local band structure and enhance the charge carrier transport across local junctions/contacts by exhibiting substantial influence on the concentration or distribution of free carriers and interfacial electronic charged states in the applied devices. The basic physics principles guiding piezotronics and piezo-phototronics are employed in this dissertation. Functional electronic/optoelectronic devices based on 2-dimensional piezoelectric semiconductor materials couple with piezoelectric and semiconductor properties are presented to demonstrate the practical applications of the piezotronic and piezo-phototronic effects, including bipolar transistors, solar cells, and photodetectors. By successfully applying the piezotronic and piezo-phototronic effects in a different range of electronic/optoelectronic devices, we have shown how these two effects can be utilized in various practical applications as effective way of modifying the physical properties of charge carriers in piezoelectric semiconductors. The method is based on theoretical research, mathematical modeling and design, supplemented by simulation results.
报告人简介: Michael Gyan, 博士生, 二维材料光电器件, 压电电子学与压电光电子学
博士生导师: 张岩 教授
日期：10月23日 15:00 – 17:00