Few-layer Tellurium: one-dimensional-like layered elementary semiconductor with striking physical properties.

Few-layer Tellurium, an elementary semiconductor, succeeds most of striking physical properties that black phosphorus (BP) offers and could be feasibly synthesized by simple solution-based methods. It is comprised of non-covalent bound parallel Te chains, among which covalent-like feature appears. This feature is, we believe, another demonstration of the previous found covalent-like quasi-bonding (CLQB) where wavefunction hybridization does occur. This CLQB introduces tunable bandgap varying from nearly direct 0.31 eV (bulk) to indirect 1.20 eV (2L) and rather complex, highly anisotropic and layer-dependent electron and hole pockets. It also exhibits an extraordinarily high hole mobility (~105 cm2/Vs) and strong optical absorption along the non-covalent bound direction, nearly anisotropic and layer-dependent optical properties, large ideal strength over 20%, better environmental stability than BP and unusual crossover of force constants for interlayer shear and breathing modes. All these results manifest that few-layer Te is an extraordinary-high-mobility, intrinsic-anisotropy, low-cost-fabrication, tunable bandgap, better environmental stability and nearly-direct bandgap semiconductor. This "one-dimension-like" few-layer Te, together with other geometrically similar layered materials, may promote the emergence of a new family of layered materials.