Introduction to the Piezotronic Effect and Sensing Applications

Abstract

The piezoelectric effect enables the direct energy conversion between mechanical and electrical energies. Piezoelectric materials have been used in actuators, transducers, and sensors in wide ranges of applications from consumable electronics like mobile phones to sophisticated instrument like Mars Rover Curiosity. Piezoelectric nanomaterials have gained increasing interests in recently year since the discovery of the energy conversion in a zinc oxide (ZnO) nanowire [1]. ZnO is also an important semiconductor material with a wide bandgap, and it is a good candidate for electronic and optical devices. The piezoelectric property and the semiconducting property can influence each other, and a new phenomenon in ZnO nanowires was discovered in 2006 [2]. Mechanical stimuli can change the polarization of a piezoelectric nanowire, and the polarization change can further tune the conductivity of the nanowire. This effect was called the piezotronic effect that was investigated in piezoelectric semiconductor nanomaterials like ZnO, zinc sulfide (ZnS), cadmium sulfide (CdS), indium nitride (InN), gallium nitride (GaN), and monolayer molybdenum disulfide (MoS2) [3–9]. The piezotronic effect is unique to piezoelectric semiconductors and enables the direct and active interaction between devices and stimuli.