The Impact of Crystal Phase on Rectification Properties of TaSi2P4–WSi2P4 Lateral Heterojunctions

Abstract

The Schottky barrier height is generally regarded as the main factor affecting the rectifying performance of two-dimensional Schottky diodes. However, the crystal phase of the component two-dimensional materials also exerts a significant influence on the electrical properties of the diodes, and the underlying mechanism remains unclear. Based on the first-principles calculations, we take the lateral heterojunctions consisting of metallic TaSi₂P₄ and semiconducting WSi₂P₄ with well-matched lattice constants and different crystal phases as examples to reveal the impact of the crystal phase on the rectification properties. Combined investigations on material work functions, electrostatic difference potential, and interfacial charge transfer verify the emergence of n-type Schottky contact in TaSi₂P₄–WSi₂P₄ heterostructures. A remarkable rectifying behavior can be observed from the volt–ampere characteristic curves of the Schottky diodes. The heterojunction diode composed of TaSi₂P₄ and WSi₂P₄ with different crystal phases and large bandgap exhibits the lowest current and the highest rectification ratio (RR) (above 10⁴). Here, the crystal phase of the component materials exerts an important impact on the electrical performance of the diodes, via tuning the bandgap, work function, and interfacial configuration. Increasing the semiconductor layer length within the heterojunction system effectively enhances the rectification performance, since the current asymmetry under forward and reverse bias is increased as the semiconductor length expands. A respectable RR of near 10⁵ is achieved in the heterojunction diode at low bias voltages by merely altering the central transition metal atomic layer within the septuple-atomic-layer materials. It may be promising to realize by lateral epitaxial growth of the heterojunction than those systems containing multiple distinct atomic layers in a septuple-atomic-layer structure. These calculations provide an insightful understanding of the influence factors on the rectification properties of lateral heterojunctions and also provide a guideline for the design of high-performance rectifiers.