DETERMINATION OF DEFECT DISTRIBUTIONS FROM ADMITTANCE MEASUREMENTS AND APPLICATION TO CU(IN,GA)SE-2 BASED HETEROJUNCTIONS

A method to deduce energy distributions of defects in the band gap of a semiconductor by measuring the complex admittance of a junction is p roposed. It consists of calculating the derivative of the junction cap acitance with respect to the angular frequency of the ac signal correc ted by a factor taking into account the band bending and the drop of t he ac signal over the space charge region of the junction. Numerical m odeling demonstrates that defect distributions in energy can be recons tructed by this method with high accuracy. Defect distributions of pol ycrystalline Cu(In,Ga)Se-2 thin films are determined by this method fr om temperature dependent admittance measurements on heterojunctions of Cu(In,Ga)Se-2 with ZnO that are used as efficient thin film solar cel ls. (C) 1996 American Institute of Physics.