Electroreflectance spectroscopy on CdS and Zn(O,S) buffer layers in Cu(In,Ga)Se2 solar cells: Suppression of interference effects

Electroreflectance (ER) spectroscopy is utilized to study Cu(In,Ga)Se
₂
solar cells with solution-grown CdS and Zn(O,S) buffer layers. Due to the weak ER signals of the thin buffer layers, interference effects can have a strong influence on the ER spectra. To suppress these interference effects, the thickness of the ZnO window layer, and hence the interference conditions, are changed by a step-by-step etching process while keeping the solar cell operational. This method was successfully applied to solar cells with CdS buffer. First results from transferring this approach to alternative Zn(O,S) buffer layers are also reported.