A two-dimensional TaGe2P4–WSi2As4 van der Waals heterojunction: A near-ideal rectifier

Abstract

Searching for suitable 2D metal-semiconductor interfaces to design high-performance Schottky diodes is essential for the continuous miniaturization of devices. Herein, by using the first-principles calculations, we propose a near-ideal two-dimensional van der Waals rectifier consisting of the monolayer TaGe₂P₄ metal and the WSi₂As₄ semiconductor with ultra-clean interface and free dangling bonds. The van der Waals heterojunction has a p-type Schottky contact at both the vertical and lateral interfaces. The Schottky barriers lead to the asymmetry of electronic transport under the positive and negative bias voltages, thus resulting in a remarkable rectification behavior. The rectifying properties can be improved by regulating the length of the semiconductor and the overlapping region, and an ultra-high rectification ratio of 10⁷ is obtained at a low bias voltage. The origin of the rectification effect and the regulating mechanism are explained in terms of the projected local density of states, transmission eigenstates, potential drop, and transmission spectra. It is found that increasing the relative length of the semiconductive part in the device enlarges the width of the Schottky barrier, which largely reduces the reverse current dominated by the electron tunneling while little affects the positive current, and thus leads to a significant improvement in the rectification performance. These results suggest that the TaGe₂P₄–WSi₂As₄ van der Waals heterojunction has promising application as a near-ideal rectifier.