Modulated photoconductivity study of charged and neutral defects in undoped amorphous silicon

A spectroscopic method involving modulated photoconductivity (MPC) analyses for different illumination levels helps determine energy distribution and capture coefficients of neutral and charged defect states in undoped amorphous silicon. Capture coefficient estimates are temperature-independent and distribute defects in the 0.2 to 0.7 eV energy range with an exponential band tail and Gaussian-shaped deep-defect band. An MPC model simulating these results suggests the contribution of nonelectronic effects to defect development in the presence of neutral dangling bonds.