Investigation of Deep-level Defects in CuGaSe2Thin-film Solar Cells by Transient Photo-capacitance Spectroscopy

Properties of deep-level defects in CuGaSe2 thin-film solar cells were investigated using transient photo-capacitance (TPC) spectroscopy. Two Gaussian-shaped deep-level defects centered at around 0.8 eV and 1.54 eV above the valence band were identified. The electronic structure of the two defects was illustrated by a configuration coordinate model to explain the thermal quenching effect in the two defects, which considered a large lattice distortion for the 0.8 eV defect while no distortion for the 1.54 eV defect.