Admittance spectroscopy was measured on Cu(In,Ga)(S,Se)2thin film and single crystal heterojunctions. The emission rates of defects for various near‐stoichiometric compositions follow a Meyer–Neldel rule, showing increasing attempt‐to‐escape frequencies with increasing defect depth. Defects in highly (In,Ga)‐rich material showed lower attempt‐to‐escape frequencies and follow a separate Meyer–Neldel relation. Repetitive air annealing of a CuInSe2heterojunction revealed a shift of the depth and capture cross section of an observed defect. ©1996 American Institute of Physics.