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