MSE Ph.D. Proposal – Ruomeng Yu

Date: Thursday, October 09, 2014
Time: 10:00 am – 12:00 pm
Location: MRDC 3515

Committee:
Dr. Zhong Lin Wang, advisor (MSE)
Dr. Meilin Liu (MSE)
Dr. Russell D. Dupuis (ECE/MSE)
Dr. Benjamin D.B. Klein (ECE)
Dr. Oliver Brand (ECE)

Title: Piezotronics/Piezo-phototronics: Devices and Applications

Abstract:

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 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 structure also possess piezoelectric properties but are not as extensively utilized in piezoelectric sensors and actuators due to their relatively small piezoelectric coefficients. The coupling of piezoelectric polarization with semiconductor properties in these materials has resulted in both novel fundamental phenomenon and unprecedented device applications, leading to the increasing research interests in the emerging field of piezotronics and piezo-phototronics. The core of piezotronics and piezo-phototronics lies in the fact that strain-induced polarization charges at interface can effectively modulate the local interfacial band structure and hence the charge carrier transport across junction/contact formed in piezoelectric semiconductor devices, by exerting substantial influence on the concentration/distribution of free carriers and interfacial electronic charged states in the device. I will provide a review on the fundamental physics involved in the research field of piezotronics and piezo-phototronics, followed by the corresponding devices and applications accomplished in my past three years research activities.