Defect study of Cu2ZnSn(SxSe1-x)4 thin film absorbers using photoluminescence and modulated surface photovoltage spectroscopy

Abstract

Defect states in Cu2ZnSn(SxSe1-x)4 thin films with x=0.28, 0.36, and 1 were studied by combining photoluminescence (PL) and modulated surface photovoltage (SPV) spectroscopy. A single broad band emission in the PL spectra was observed and can be related to quasi-donor-acceptor pair transitions. The analysis of the temperature dependent quenching of the PL band (x=0.28, 0.36, and 1) and SPV (x=0.28) signals resulted in activation energies below 150meV for PL and about 90 and 300meV for SPV. Possible intrinsic point defects that might be associated with these observed activation energies are discussed.