Role of Interfacial Interaction Type in Rectifying the Behaviors of Lateral and Vertical Heterojunction Schottky Diodes

The performance of a two-dimensional Schottky diode largely depends on its metal-semiconductor interfacial contact. However, the impact of the interfacial interaction type on the electrical performance remains elusive. Here, we reveal the role of the interfacial interaction type in rectifying behavior of lateral and vertical heterojunction Schottky diodes, taking the heterojunctions composed of two-dimensional metallic TaGe₂P₄ and semiconducting WSi₂As₄ with well-matched crystal structures and lattice constants as examples. The interfacial properties and rectification performance are comprehensively investigated using first-principles calculations. We find that the vertical heterojunction creates more obstructions for electron tunneling than the lateral counterpart due to the combined effect of the vertical and lateral Schottky barriers, thus leading to lower current and more conspicuous rectifying behavior. By tuning the metal-semiconductor relative length within the sub-5 nm diodes, the maximum rectification ratios of more than 10⁵ and 10⁷ are obtained for the lateral and vertical heterojunction diodes, respectively, comparable to those of traditional p-n junctions (10⁵-10⁷). The regulating mechanism is attributed to the variation in Schottky barrier width, which has a large impact on the reverse current while affects the forward current slightly, thus significantly regulating the rectification performance. These calculations provide a thorough understanding of the effect of interfacial properties on the rectification performance of lateral and vertical heterojunction rectifiers.