First principle simulations of piezotronic transistors

Piezoelectric semiconductor materials, such as wurtzite ZnO, GaN, InN, and CdS, have drawn intensive research interests for fabricating functional electronics. Under an externally applied mechanical strain, piezoelectric charges (piezocharges) are created at a metal-semiconductor interface or a pn junction, which are likely to tune the local Schottky contact or charge-depletion zone and can be used as a new means for "gating" carrier transport. Piezotronics is a new emerging field using piezoelectric semiconductor[1]. Piezotronic effect has been studied and utilized for two-terminal strain gated transistors [2], logic devices and memory units [3], enhancing solar cell and LED efficiency [4], and enhanced sensing [5]. Recently, piezotronic array and chip devices have been developed as flexible human-machine interfacing [6] and photonic-strain mapping [7], setting a milestone from fabricating single devices to an array of devices and even to an integrated system [8].