Defect levels in Cu(In1−xGax)Se2 were studied by using admittance spectroscopy with varying Ga concentration of x from 0.38 to 1.0. Two distinct peaks (α and ζ) were detected from all of the samples. Peak α could be attributed to shallow acceptors. Peak ζ was closely correlated with the surface potential and therefore could be caused by traps near to the surface, such as grain-boundary defects. The intensity of peak ζ increased with increasing Ga concentration. It was suggested that degradation of the performance of solar cells, with increasing Ga concentration, might be related to the defects corresponding to peak ζ˙.

Investigation of Relation between Ga Concentration and Defect Levels of Al/Cu(In,Ga)Se2 Schottky Junctions Using Admittance Spectroscopy. T.Sakurai, N.Ishida, S.Ishizuka, K.Matsubara, K.Sakurai, A.Yamada, G.K.Paul, K.Akimoto, S.Niki: Thin Solid Films, 2007, 515[15], 6208-11