The first-principles study of structural and electronic properties of two-dimensional SiC/GeC lateral polar heterostructures

Abstract

Two-dimensional (2D) lateral polar heterostructures, constructed by seamlessly stitching 2D polar materials, exhibit unique properties triggered by the in-plane charge transfer between different elements in each domain. Our first-principles study of 2D SiC/GeC lateral polar heterostructures has unraveled their interesting characteristics. The local strain induced by a lattice mismatch leads to an artificial uniaxial strain along the interface. The synergistic effect of such uniaxial strain, the microstructure of interface, and the width of domains modulates the feature of the bandgap with an indirect bandgap nature in armchair lateral heterostructures and a direct bandgap nature in zigzag lateral heterostructures. The bandgap monotonically decreases with increasing the width of domains, showing its tunability. Furthermore, the valence band maximum is found to be mainly contributed from C-2p orbitals located at both GeC and SiC domains, and the conduction band minimum is mainly contributed from Ge-4p orbitals located at the GeC domain, implying that most excited electrons prefer to stay at the GeC domain of the SiC/GeC lateral polar heterostructures. Interestingly, a net charge transfer from the SiC domain to the GeC domain was found, resulting in a spontaneous lateral p–n junction, and there is a net charge redistribution at the interfacial region leading to a built-in electric field which is expected to reduce the carrier recombination losses, implying the promising application for visible light photocatalyst, photovoltaics, and water splitting to achieve clean and renewable energy.