Optical absorption in silicon layers in the presence of charge inversion/accumulation or ion implantation

We determine the optical losses in gate-induced charge accumulation/inversion layers at a Si/SiO2 interface. Comparison between gate-induced charge layers and ion-implanted thin silicon films having an identical sheet resistance shows that optical losses can be significantly lower for gate-induced layers. For a given sheet resistance, holes produce higher optical loss than electrons. Measurements have been performed at λ = 1550 nm.