Fundamental Theory of Piezotronics

TLDR

Polarization of ions in noncentral‑symmetry crystals such as ZnO, GaN, and InN generates a piezoelectric potential that can be used as a gate voltage in piezotronic devices, offering force‑sensing, MEMS, and nanorobotics applications distinct from conventional CMOS transistors. This work investigates the theory of charge transport in piezotronic devices. The authors present a formal theoretical framework and analytical solutions for metal–semiconductor contacts and p–n junctions under simplified conditions. Numerical calculations predict the current–voltage characteristics of a metal–ZnO nanowire–metal transistor, providing insight into device operation and design guidance.

Abstract

Abstract Due to polarization of ions in crystals with noncentral symmetry, such as ZnO, GaN, and InN, a piezoelectric potential (piezopotential) is created in the crystal when stress is applied. Electronics fabricated using the inner‐crystal piezopotential as a gate voltage to tune or control the charge transport behavior across a metal/semiconductor interface or a p–n junction are called piezotronics. This is different from the basic design of complimentary metal oxide semiconductor (CMOS) field‐effect transistors and has applications in force and pressure triggered or controlled electronic devices, sensors, microelectromechanical systems (MEMS), human‐computer interfacing, nanorobotics, and touch‐pad technologies. Here, the theory of charge transport in piezotronic devices is investigated. In addition to presenting the formal theoretical frame work, analytical solutions are presented for cases including metal–semiconductor contact and p–n junctions under simplified conditions. Numerical calculations are given for predicting the current–voltage characteristics of a general piezotronic transistor: metal–ZnO nanowire–metal device. This study provides important insight into the working principles and characteristics of piezotronic devices, as well as providing guidance for device design.