Density of surface states in Li doped a-Si:H

Sub-band gap absorption measured using constant photocurrent measurement and photothermal deflection spectroscopy have been used as complementary techniques to obtain the density of surface states in lithium doped hydrogenated amorphous silicon [a-Si:H(Li)]. This method has the advantage that it obviates the need to make identical samples of varying thicknesses. We find a surface state density of ≈5 × 1012 cm−2 in a-Si:H(Li), for the two Li concentrations studied.