Journal of Nanomedicine & Nanotechnology

Piezophototronic based sensors and applications

22^nd International Conference and Expo on Nanoscience and Molecular Nanotechnology

November 06-08, 2017 | Frankfurt, Germany

Junyi Zhai

Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Science, Beijing, China

Scientific Tracks Abstracts: J Nanomed Nanotechnol

Abstract:

Multifunctional micro/nano devices and systems are of important applications in smart electronics for health care, humanmachine 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 piezophototronic 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. When combine piezophototronics effect with magnetostriction, multifield couplings can be realized. For example, magneto-optics and electro-optics, magneto-electrics and magneto-mechanics, piezotronics and piezophototronics, which could be of interest for fabricating functional devices in the fields of energy conversion, magnetic/optical imaging, high-density optical communication and information storage, smart sensing, and so on. 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.

Biography :

Junyi Zhai is a professor in the Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Science, leading the group of Micro/Nano Piezoelectric Materials and Devices. He was a Director’s postdoctoral fellow in Loa Alamos National Laboratory. He received his B.S. in Chemistry from Tsinghua University; M.E. in Materials Science and Engineering from Tsinghua University; Ph.D. from Virginia Tech in Materials Science and Engineering. His main research interests are fundamental and technological investigation of functional materials and multi-fields coupling for applications in electronics, sensors and energy. Prof. Zhai has authorized or co- authorized 70 papers with over 3000 citations.