Novel Janus [formula omitted]-Au[formula omitted]XY (X/Y = S, Se, Te) monolayers with ultra-high carrier mobility: A first-principles study

Abstract

In this paper, we theoretically propose a series of Janus α-Au4XY (X/Y = S, Se, Te; X ≠ Y) monolayers and investigate their structural stability, electronic features, and transport properties based on first-principle calculations. It is indicated that Janus α-Au4XY monolayers have a structurally stable and can be synthesized experimentally. Janus α-Au4XY monolayers exhibit a low Young’s modulus and their mechanical features are slightly anisotropic. At the ground state, Janus α-Au4XY monolayers possess semiconducting characteristics with very steep band dispersions near the conduction band minimum, which is expected to ultra-high electron mobility. The electronic features of Janus α-Au4XY are highly sensitive to the biaxial strains ɛxy, particularly the applied compressive biaxial strains. Interestingly, the transitions from the semiconductor to the metal phases are observed in all three configurations of α-Au4XY at ɛxy=−6%. Janus α-Au4XY monolayers exhibit superior transport characteristics with the electron mobility reaching up to 3.20×105 cm2V−1s−1 (α-Au4SSe monolayer). Our findings not only explore the outstanding electronic and transport features of Janus α-Au4XY nanostructures but also indicate their potential applications in nanoelectronics and nanoelectromechanical devices.