Capacitance profiling in the CIGS solar cells

Capacitance-voltage profiling and drive level capacitance profiling have been used in order to determine net shallow acceptor concentration in the absorbers of Cu(In,Ga) Se-2-based solar cells. Metastable changes of the net doping distribution produced by reverse bias and light soaking have also been investigated. We discuss the influence of deep levels on the results and attribute apparent non-uniformity of profiles to charges accumulating in the interface region of the device. Conductivity of thin films prepared in the same process as absorbers in the cells under investigation, in the relaxed and light-soaked state has also been measured. The results provide additional arguments that capacitance methods give realistic estimation of doping level of absorber in photovoltaic devices. (C) 2007 Elsevier B.V. All rights reserved.