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

Sub-band gap absorption measured using constant photocurrent measurement an d photothermal deflection spectroscopy have been used as complementary tech niques to obtain the density of surface states in lithium doped hydrogenate d amorphous silicon [a-Si:H(Li)]. This method has the advantage that it obv iates the need to make identical samples of varying thicknesses. We find a surface state density of approximate to 5 x 10(12) cm(-2) in a-Si:H(Li), fo r the two Li concentrations studied. (C) 1998 Published by Elsevier Science B.V. All rights reserved.