(Correspondent: Xiaoxuan Duan)ACS Nano(Impact Factor is 19.942),top international journal in field of materials, reportedDouble-Channel Piezotronic Transistors for Highly Sensitive Pressure Sensing, the latest research finding of School of Advanced Materials and Nanotechnology, Xidian University. Liu Shuhai, Professor Qin Yong's first-year Doctoral student, is the lead author, and the School of Advanced Materials and Nanotechnology, Xidian University is the lead communication unit.

It is of great importance to study the interface phenomena and interface control in semiconductor devices for their applications in electronics and optoelectronics. Piezoelectric effect is considered to be an effective means to control the interface energy band of semiconductor devices by using the coupling between piezoelectric and semiconductor properties. In semiconductor devices, the piezoelectric polarization bound charge generated by piezoelectric effect will change the distribution of free carriers at the interface of materials, resulting in band bending, thus realizing the control of electrical transport signal by mechanical driving signal. Such devices are usually called piezotronics transistors which are widely used in fields of human-machine interfacing, active sensor, active flexible electronics, micro robots, intelligent electronic signature, intelligent micro-nano electromechanical system and energy technology, etc. Therefore, they have a great potential in applications.

In recent years, the pressure sensitivity of piezoelectric transistors has been improved rapidly by exploring new piezoelectric semiconductor materials with high voltage coefficient or by using surface modification. However, due to the opposite piezoelectric potential at the metal semiconductor contact in the traditional structure, and the three-dimensional structure, the pressure sensitivity of the device is still limited, and the reliability needs to be improved. Therefore, it is very important to develop new piezoelectric transistors with high sensitivity and high reliability.

In this work, under the guidance of Professor Qin Yong ofSchool of Advanced Materials and Nanotechnology of our university and Wang Zhonglin, Academician of Beijing Institute of Nanoenergy and Nanosystem, Chinese Academy of Sciences, doctoral student Liu Shuhai, Dr. Wang Longfei and Dr. Wang Zheng have successfully fabricated two channel piezoelectric transistor arrays with planar structure. Using the hexagonal structure of ZnO sheets, they self-assembled ZnO sheets into aligned arrays, and obtained a pressure sensor with high pressure, strong sensitivity and high reliability by transferring ZnO sheet array to metal interdigital electrode by flexible template, so that the same polar surface of ZnO sheet contacts the two metal electrodes at the same time. They used piezoelectric effect to regulate double Schottky barrier. The pressure sensitivity of the device is as high as 84.2 ~ 104.4 MeV / MPa. In addition, the device can still work normally in the case of failure of contact at one end due to the co-direction regulation of two channels with common surface, so the device also has high reliability.

Link to the paper:http://pubs.acs.org/doi/abs/10.1021/acsnano.7b08447