Quantum piezotronic devices based on ZnO/CdO quantum well topological insulator

Developing emergent quantum piezotronic devices based on third-generation semiconductors has become the growing tendency for going beyond conventional device applications. Wurtzite ZnO is currently the leading piezoelectric semiconductor for developing high performance piezotronic nanodevices. In this study, we propose a quantum piezotronic device of ZnO quantum wells (QWs) topological insulator. Stress-induced piezoelectric field can drive the QW to be topological insulator, and the critical stress is highly dependent on the QW width. An effective Hamiltonian is calculated to identify the existence of gapless edge states, and further used to study electronic transport in quantum point contact (QPC) structure. The transport conductance can be controlled at edge states and bulk states by externally applied stress under various QPC widths and Fermi levels. A topological insulator device is proposed for manipulating quantum states among the normal and topological insulator, and robustly against the applied stress. This study provides a microscopic picture to understand piezotronic effect on topological insulator states of ZnO quantum well, and paves the way towards the flexibly integrated applications of topological insulator.