First principles prediction of electronic, mechanical, transport and optical properties of the silicane/Ga2SSe heterostructure

In this work, we investigated the electronic structure, and mechanical, transport and optical properties of the van der Waals heterostructure formed from silicane (SiH) and Janus Ga2SSe monolayers using first-principles prediction. The out-of-plane symmetry in the Janus Ga2SSe monolayer leads to the formation of two different types of Ga2SSe/SiH heterostructure, namely SGa2Se/SiH and SeGa2S/SiH stacking patterns. All stacking patterns of the SiH/Ga2SSe heterostructure are thermodynamically, mechanically and energetically stable at room temperature. Furthermore, the generation of the SiH/Ga2SSe heterostructure gives rise to a reduction in the band gap, demonstrating that the electrons move faster from the valence bands to the conduction bands. The SiH/Ga2SSe heterostructure is a semiconductor with a direct band gap of about 0.68 or 0.95 eV, depending on the stacking pattern. The SiH/Ga2SSe heterostructure forms type-II band alignment for all stacking patterns, indicating that the photogenerated carriers are separated effectively, thus enhancing the photocatalytic performance. Moreover, the carrier mobilities for electrons and holes of the Ga2SSe/SiH heterostructure are higher than those of the constituent SiH and Ga2SSe monolayers in both the x and y directions, suggesting that the performances of electronic devices based on the Ga2SSe/SiH heterostructure would be excellent and reliable. The formation of the Ga2SSe/SiH heterostructure also gives rise to an enhancement of the absorption coefficient in both the visible and ultraviolet regions. Our findings could give valuable guidance for the design of high-efficiency devices based on the SiH/Ga2SSe heterostructure.