Optical anisotropy of the In/Si(1 1 1)(4 × 1)/(8 × 2) nanowire array

Ab initio calculations of the reflectance anisotropy of Si(1 1 1)-In surfaces are presented. A very pronounced optical anisotropy around 2 eV is found that is related to In-chain states. The distortion of the indium chains characteristic for the (4 × 1) → (8 × 2) phase transition results in a splitting of the 2 eV peak, as observed experimentally. The splitting occurs irrespective wether the phase transition occurs according to the trimer or hexamer model.