First principles prediction of electronic, mechanical, transport and optical properties of the silicane/Ga(2)SSe 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 Ga(2)SSe monolayers using first-principles prediction. The out-of-plane symmetry in the Janus Ga(2)SSe monolayer leads to the formation of two different types of Ga(2)SSe/SiH heterostructure, namely SGa(2)Se/SiH and SeGa(2)S/SiH stacking patterns. All stacking patterns of the SiH/Ga(2)SSe heterostructure are thermodynamically, mechanically and energetically stable at room temperature. Furthermore, the generation of the SiH/Ga(2)SSe 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/Ga(2)SSe heterostructure is a semiconductor with a direct band gap of about 0.68 or 0.95 eV, depending on the stacking pattern. The SiH/Ga(2)SSe 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 Ga(2)SSe/SiH heterostructure are higher than those of the constituent SiH and Ga(2)SSe monolayers in both the x and y directions, suggesting that the performances of electronic devices based on the Ga(2)SSe/SiH heterostructure would be excellent and reliable. The formation of the Ga(2)SSe/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/Ga(2)SSe heterostructure.