Theoretical investigation of the role of hydrogenation-induced strain in single-layer h 10-Si.

Although great efforts have been dedicated to exploring hydrogenated two-dimensional (2D) materials, there are few reports about the role of hydrogenation-induced equivalent strain effects in tuning the physical properties. Here, based on density functional theory, we systematically reveal the non-negligible role of the hydrogenation-induced strain and its effects on the electronic and optical properties in single-layer (SL) h 10-Si. We demonstrate that hydrogenation can trigger an electronic transition from an indirect- to a direct-band-gap semiconductor mainly due to the energy level rearrangement of the partial p orbitals caused by the equivalent strain. The electronic transition in SL h 10-Si occurs at a critical hydrogenation concentration of about 87.5%. Furthermore, it is found that hydrogenation can continuously shift the light absorption peak of SL h 10-Si in the photon-energy range of 1.64-2.44 eV by changing the p z -p z dipole transition. Our findings provide an example of tuning the electronic properties of 2D materials via hydrogenation-induced strain, which is important for understanding the physical mechanism of the hydrogenation-tuned physical properties of such materials.