Van der Waals heterostructures of P, BSe, and SiC monolayers

Abstract

Electronic structure, optical, and photocatalytic properties of P, BSe, and SiC monolayers and their van der Waals heterostructures are investigated by (hybrid) first-principle calculations. The stability of the heterostructures and their corresponding induced-strain/unstrain monolayers are confirmed by the phonon spectra calculations. Similar to the corresponding parent monolayers, P-BSe (BSe-SiC) heterostructures are indirect type-II (type-I) bandgap semiconductors. A tensile strain of 10% (2%) transforms P-BSe (BSe-SiC) to type-I (type-II) direct bandgap nature. Interestingly, irrespective of the corresponding monolayers, the P-SiC heterostructure is a direct bandgap (type-II) semiconductor. The calculated electron and hole carrier mobilities of these heterostructures are in the range of 1.2 × 10 4 cm 2 / Vs to 68.56 × 10 4 cm 2 / Vs. Furthermore, absorption spectra are calculated to understand the optical behavior of these systems, where the lowest energy transitions are dominated by excitons. The valence and conduction band edges straddle the standard redox potentials in P-BSe, BSe-SiC, and P-SiC (strained) heterostructures, making them promising candidates for water splitting in the acidic solution. An induced compressive strain of 3.5% makes P suitable for water splitting at pH = 0.