The nature of the interface betweenCuInSe2(CIS) and the chemical bath deposited CdS layer has been investigated. We show that heat-treating the absorbers in Cd- or Zn-containing solutions in the presence of ammonium hydroxide sets up a chemical reaction which facilitates an extraction of Cu from the lattice and an in-diffusion of Cd. The characteristics of devices made in this manner suggest that the reaction generates a thin, n-doped region in the absorber. It is quite possible that theCdS/CuInSe2device is a buried, shallow junction with a CdS window layer, rather than a heterojunction. We have used these ideas to develop methods for fabricating devices without CdS or Cd. A 14.2&percent; efficiency ZnO/CIGS device was obtained through aqueous treatment in Zn solutions. ©1999 American Institute of Physics.