Signatures of extended defects in Cu(In,Ga)Se2 observed using capacitance spectroscopy techniques

This work concerns the interpretation of defect spectroscopy signals in CuInSe2-and Cu(In,Ga)Se2-based Schottky junctions and thin films, which are investigated using capacitance- and current-based techniques. Two common signals are distinguished. It is shown here that the activation energies and consequently the emission rates vary between the samples and are strongly correlated with the hole concentration in the material. Models that can account for these changes are discussed. Based on deep-level transient spectroscopy and conductivity measurements, we present arguments for the validity of the existing models and discuss the hypothesis that the observable signals may originate from extended defects in Cu(In,Ga)Se2.