Phosphorus doping effect on linear and nonlinear optical properties of Si/SiO 2 multilayers

The linear and nonlinear optical properties of phosphorous-doped Si/SiO2 multilayers as a function of doping concentration were investigated. It was found that the linear optical absorption became weak with the doping concentrations while the corresponding nonlinear optical absorption coefficient was reduced by 4 folds after phosphorus doping. Our experimental results demonstrated that the interface states were passivated by the phosphorus dopants which changed the chemical environment of the Si nanoclusters and in turn affected both the linear and nonlinear optical processes. The excitation-wavelength dependent nonlinear optical behaviors also supported our proposed model. It was suggested that the linear and nonlinear optical properties can be tunable via controlling the phosphorous doping concentrations which provided a new approach to improve the performance of nano-Si-based photonic devices.