Fabrication of Cu(In,Ga)Se2 Thin Films with Various Cu Content

Abstract

Cu(In,Ga)Se2 (CIGS) thin films with three different Cu contents were prepared by magnetron sputtering from quaternary CIGS targets, followed by post-annealing under Se-containing atmosphere. The properties of Cu(In,Ga)Se2 film and related solar cell were investigated. XRF confirms the composition of the films with different Cu contents. X-Ray Diffraction peaks of all samples correspond to the chalcopyrite structure, however, which are difficult to distinguish the overlapped Cu2-xSe phase. SEM results find the grain-size distribute uniformly through the entire depth, and improve noticeably with the increase of the Cu excess. Hall Effect Measurements indicate the change of the resistivity and carrier concentration as function of Cu contents. When the excess of Cu is increased, the performances of the related solar cells were damaged greatly and good photovoltaic characteristics cannot be obtained.