Nonlinear Concentration-Dependent Electronic and Optical Properties of Si1-xGex Alloy Nanowires

Nonlinear concentration-dependent electronic and optical properties of the Si1-xGex substitutional alloy nanowires are investigated using first-principles calculations. The nonuniform distribution of Ge (or Si) atoms is found, and the resulting orbital hybridization of the inner Ge or Si atoms results in the nonlinear Ge concentration dependence of electronic properties in the Si1-xGex alloy NWs, which suggests an effective approach to modulate band-gap properties of the NWs along all three directions. Moreover, a strong adsorption of solar radiation and a high quantum yield is predicted in (110)-oriented alloy NWs, which implies a great potential of Si1-xGex alloy NWs in the optical electronics applications on nanoscale.