Defect levels in CuGaSe2 by modulated photocurrent spectroscopy

Results of high frequency modulated photocurrent spectroscopy (HF MPC) performed on epitaxial and polycrystalline CuGaSe2 thin films are presented. Frequency and temperature scans of MPC in the high frequency regime are compared, and the advantages of the second mode of measurement over the first one are demonstrated. Electronic parameters of defect levels in Cu-rich and Ga-rich stoichiometry are obtained and discussed in comparison to the literature data on defect levels derived from capacitance junction techniques. An attempt to correlate levels observed by MPC technique with material stoichiometry has been made.