Enhanced electromechanical performance in metal–MgO–ZnO tunneling diodes due to the insulator layers

Abstract

The enhanced electromechanical performance of metal–insulator–semiconductor tunneling diodes (MISTDs) based on ZnO nanostructures is investigated through modeling in the framework of the Schrödinger equation with effective-mass approximation. It is found that the performance of ZnO based diodes is greatly improved by inserting an MgO layer which allows the inhibition of the screening effect. The piezoelectric response of MISTDs is much higher than that of metal–semiconductor–metal Schottky diodes MSMSDs. The current of the MISTDs is almost zero at −2% compressive strain and increases to a much higher value (∼600 nA) than that of the MSMSDs (∼400 nA) at +2% tensile strain. The enhancement mechanism of MISTDs is investigated by examining the electron density, electric field, electrostatic potential and conduction band edge of the device. The results found that the origin of the enhanced electromechanical performance is due to the inhibition of screening effects by the insulating MgO layer which leads to a highly strain sensitive energy barrier in the ZnO layer and an extra energy barrier in the MgO layer with a strain modulated height.

The international collaborative research between the School of Materials Science and Engineering, University of Science and Technology Beijing and the School of Electrical and Electronic Engineering, University of Manchester started in 2014 with financial support from the program of introducing talents of discipline to universities in PRC. This project supports cooperative research studies and academic exchanges between Chinese universities and famous scientists from world-renowned universities, covering international travel expenses, daily living expenses of visiting scientists and costs of joint research studies. The Anglo-Sino collaboration is also supported by the Newton International Research Collaboration Programme, covering long term residence of the UK staff at Chinese partner universities and some research costs.

Prof. Max Migliorato has been coming to the University of Science and Technology Beijing for collaborative research since 2014, spending around 6 months in total in China, particularly during his sabbatical leave, conducting joint research in the field of theoretical simulation of material properties and device performances, and experimental studies on graphene and related 2D materials and devices.