Anisotropic High Carrier Mobilities of One-Third-Hydrogenated Group-V Elemental Monolayers

Group-VA elemental monolayers, such as arsenene, antimonene, and bismuthene, are predicted to be wide band gap semiconductors, which are potential candidates for future nanodevices in spintronics and optoelectronics. We employ first-principles calculations to investigate the atomic structures and electronic properties of one-third-hydrogenated (OTH) group-VA elemental monolayers, that is, OTH-X (X = arsenene, antimonene, or bismuthene). Because of the hydrogenation, the threefold rotation symmetry of group-VA elemental monolayers is annihilated. This leads to the anisotropic electronic and optical properties, such as carrier (electron or hole) mobility and light absorbance. The band gaps of OTH-X are also tuned effectively compared to those of pristine group-VA elemental monolayers. Remarkably, OTH-bismuthene (OTH-Bi) shows an energy band gap inversion induced by external compression, implying a topological phase transition. Furthermore, the carrier mobilities of OTH-Bi for electron and hole along the zig-zag direction are on the order of 105 cm2 V-1 s-1, which is comparable to those of graphene. The hole mobilities of OTH-arsenene (OTH-As) and OTH-antimonene (OTH-Sb) along the zig-zag direction can reach as high as 3.8 × 104 and 3.0 × 103 cm2 V-1 s-1, respectively. Our results show that atomically precise functionalization of two-dimensional materials can effectively enhance the intrinsic electrical properties, which may have potential applications in future electronic and spintronic devices.