Novel electromechanical coupling theory of GaN HEMT structure under mechanical clamping

Key Laboratory of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University - Xi'an 710071, China

^(a) E-mail: zhaotl@xidian.edu.cn (corresponding author)

Received: 9 September 2022
Accepted: 30 January 2023

Abstract

As known, the piezoelectric polarization effect makes GaN HEMT have unique electrical characteristics and wider applications compared with other III-V semiconductor devices. In this letter, a novel electromechanical coupling theory is proposed and verified for the first time for the GaN HEMT heterojunction structure by applying the mechanical clamping boundary conditions in piezoelectric constitutive equations. The total piezoelectric polarization defined as P_couple in this new electromechanical coupling theory consist of three parts: the spontaneous polarization P_sp, the strain-induced piezoelectric polarization P_strain due to lattice mismatch in growth, and the bias-dependent piezoelectric polarization . The output and transfer characteristics of GaN HEMT have been simulated based on the new electromechanical coupling theory and verified in agreement with the experimental results in trend. This theory helps to extend the understanding of the basic physical mechanism of the AlGaN/GaN interface and is of great significance to device design and application for GaN-based materials.