Low energy muon study of the p-n interface in chalcopyrite solar cells

The slow muon technique was used to study the p-n junction of chalcopyrite solar cells. A defect layer near the interface was identified and the passivation of the defects by buffer layers was studied. Several cover layers on top of the chalcopyrite Cu(In,Ga)Se2 (CIGS) semiconductor absorber were investigated in this work, namely CdS, ZnSnO, Al2O3 and SiO2. Quantitative results were obtained: The defect layer extends about 50 nm into the CIGS absorber, the relevant disturbance is strain in the lattice, and CdS provides the best passivation, oxides have a minor effect. In the present contribution, specific aspects of the low-energy muon technique in connection with this research are discussed.