SCIENCE CHINA Technological Sciences © Science China Press and Springer-Verlag Berlin Heidelberg 2015 tech.scichina.com link.springer.com *Corresponding authors (email: zhangyan@lzu.edu.cn; zlwang@gatech.edu)  Article  August 2015 Vol.58 No.8: 1348–1354 doi: 10.1007/s11431-015-5873-5 Piezotronic transistors in nonlinear circuit: Model and simulation HU GongWei 1 , ZHANG YuJing 1 , LUO Lu 1 , YANG Yang 1 , ZHANG Yan 1,2* & WANG ZhongLin 2,3* 1 Institute of Theoretical Physics, and Key Laboratory for Magnetism and Magnetic Materials of MOE, Lanzhou University, Lanzhou 730000, China; 2 Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China; 3 School of Material Science and Engineering, Georgia Institute of Technology, Georgia 30332, USA Received May 21, 2015; accepted June 12, 2015; published online July 2, 2015 For the materials that simultaneously exhibit piezoelectric and semiconductor properties, such as wurtzite ZnO, GaN and InN, as well as two-dimensional single MoS 2 , piezoelectric charges induced by externally applied strain can tune/control carrier transport at a metal-semiconductor contact or semiconductor junction, which is named piezotronic effect. Metal-semiconduc- tor-metal piezotronic transistors are key piezotronic nanodevices for electromechanical applications, and they are typical non- linear elements. In this paper, a simplified current-voltage analysis solution of piezotronic transistors is developed, which can be used for circuit design and simulation. Furthermore, the typical nonlinear circuit: Chua’s circuit based on piezotronic tran- sistors is simulated. We find that the output signal of the piezotronic transistor circuit can be switched and changed asymmet- rically by externally applied strain. This study provides insight into the nonlinear properties of the piezotronic transistor, as well as guidance for piezotronic transistor nonlinear circuit application. piezotronic transistor, nonlinear nanodevice, electromechanical application, nonlinear circuit Citation: Hu G W, Zhang Y J, Luo L, et al. Piezotronic transistors in nonlinear circuit: Model and simulation. Sci China Tech Sci, 2015, 58: 13481354, doi: 10.1007/s11431-015-5873-5 1 Introduction Piezoelectric semiconductors, such as wurtzite ZnO, GaN, and InN, have attracted increasing attention for their cou- pled piezoelectric and semiconductor properties [1]. Piezo- tronic effect is about the use of piezoelectric charges to tune/control the carrier transport characteristics at an inter- face or junction under applied strain, based on which, many unique electromechanical functional devices have been de- signed and developed, such as nanogenerators [2–4], piezo- electric field effect transistors [5], piezotronic sensors [6–8], logic devices [9], piezo-phototronic devices [10,11], piezo- tronic transistor and photonic-strain sensor array integrated system for flexible human-machine interface [12,13]. Re- cently, piezotronic transistors have been fabricated by two-dimensional (2D) single-atomic-layer MoS 2 [14]. As high sensitivity electromechanical functional electronic de- vices, piezotronic transistors can be used in force/pressure sensing, triggering, human-computer interfacing systems [15]. Theoretical studies have been demonstrated to under- stand carrier transport behavior for piezotronic transistors [16]. Based on this, a simulation model can be developed for circuit based on piezotronic transistors, and used for circuit design and application by electronic design automa- tion (EDA) software systems. According to previous ex- perimental and theoretical studies, piezotronic transistor has nonlinear current-voltage characteristics [6,16], which can