Eliminating interference effects in picosecond photoinduced absorption decays: Application to intrinsic hydrogenated amorphous silicon

Abstract

We measure picosecond photoinduced absorption in a low-defect sample of intrinsic hydrogenated amorphous silicon. Our results indicate that both the imaginary and real parts of the complex index of refraction contribute to the observed decay of the induced transmittance. We present methods for obtaining the undistorted decay of the induced absorption. We show that the decay of the induced absorption depends strongly on the peak carrier density and the repetition rate of the excitation source. The photoinduced absorption decays are consistent with the model for dispersive transport in amorphous materials.