Two-dimensional SiC Schottky junctions with symmetrical and asymmetrical metal electrode contacts

Abstract

Four symmetrical and six asymmetrical Schottky contacts in the metal–semiconductor-metal structures were constructed by using two-dimensional (2D) SiC material as channel and four metal materials (Ag, Al, Au, Pd) as electrodes. On the basis of density functional theory and ab initio calculation method, devices’ transmission spectra, current–voltage characteristics, local density of states, rectification ratio, current–temperature characteristics and negative differential thermoelectric resistance were studied. The results show that Schottky contact is formed between the four metal materials and the 2D SiC. Partially asymmetrical metal electrode structure devices have excellent rectification characteristics. The device has the optimal rectification characteristics with a rectification ratio of 747 when Pd and Au are used as asymmetrical electrodes. Moreover, the temperature dependence of thermionic excitation transport has a key influence on the rectification properties of the device. The rectification ratio reaches to 2100 around 200 K in the junction of Pd–SiC–Au. A key finding is that the negative differential thermoelectric resistance can be generated in Pd–SiC–Au device when a temperature difference applied between two electrodes without external bias voltage. The results of this study can provide theoretical reference for the subsequent design of transistors and other device based on 2D SiC material.