A review was presented of recent results on the transient photocapacitance spectroscopy, surface chemistry and depth-resolved cathodoluminescence of polycrystalline device layers, and of single-crystal epitaxial layers having 3 orientations. The results were combined with device modeling in order to provide a picture of near-surface defect structures. Transient photocapacitance spectroscopy results revealed deep defect levels which were about 0.7 and 0.9eV above the valence band. Cathodoluminescence data revealed evidence of a sub-gap radiative recombination which increased sharply near to the sample surface. The results implicated a near-surface Cd-containing layer which could be responsible for surface carrier-type inversion, a near-surface region which contained a high defect density (possibly near to the valence band edge) and deep hole traps near to the conduction band.

Near-Surface Defect Distributions in Cu(In,Ga)Se2. A.Rockett, D.Liao, J.T.Heath, J.D.Cohen, Y.M.Strzhemechny, L.J.Brillson, K.Ramanathan, W.N.Shafarman: Thin Solid Films, 2003, 431-432, 301-6