Two-dimensional Janus group-III ternary chalcogenide monolayer compounds B2XY, Al2XY, and BAlX2 (X, Y = S, Se, Te) with high carrier mobilities

Abstract

First-principles approach based on density functional theory is employed in order to investigate the structural, electronic, and mechanical properties of the two-dimensional Janus group-III ternary chalcogenide monolayer (G3TCM) semiconductor series, B2XY, Al2XY, and BAlX2 (X, Y = S, Se, Te; X ≠ Y). The effective masses, band gaps, and carrier mobilities of the entire series of Janus G3TCM compounds are evaluated to comprehensively examine their feasibility as an ingredient in nanoscale electronic device. All the G3TCM compounds proposed in this study are suggested to be realizable based on phonon calculations and estimated mechanical stability. The indirect bandgap of B2XY and Al2XY can be switched to direct bandgap in BAlX2 by constructing Janus-type structure using group-III elements. The computationally obtained carrier mobilities according to the deformation potential theory indicated that B2SSe and BAlSe2 have exceptional electron and hole carrier mobility of 2.02 x 104 and 2.58 x 105 cm2 V-1 s-1, respectively, at room temperature.