Schottky diodes based on in-plane TaSi2N4–WGe2N4 and TaSi2N4–MoGe2N4 heterojunctions

Abstract

Ideal metal–semiconductor interfaces in 2D lateral heterojunctions are important to realize high-performance Schottky diodes. Based on the first-principles calculations, we propose in-plane heterojunction diodes composed of the metallic TaSi2N4 and the semiconductive WGe2N4/MoGe2N4 monolayers with extremely low lattice mismatch and nearly free defect states. N-type Schottky contacts are confirmed in both TaSi2N4–WGe2N4 and TaSi2N4–MoGe2N4 heterojunctions by analyzing the energy band alignment, charge transfer, electrostatic differential potential, and effective potential. Then, the volt-ampere characteristics and the rectification effect of heterojunctions are investigated. An ultrahigh rectification ratio of 106/107 is obtained for the TaSi2N4–WGe2N4/MoGe2N4 heterojunction diode via regulating the length of the semiconductor part of the heterojunctions. The regulatory mechanism is elucidated by the asymmetrical evolutions of transmission spectra within positive and negative energy ranges. Finally, the rectification mechanism is revealed by the local density of states and the potential energy drop under bias voltages. These results provide a guideline for designing in-plane heterojunction diodes with ultrahigh rectification.