Composition control of electrodeposited Cu-In-Se layers for thin film CuInSe2 preparation

Electrodeposition of Cu-In-Se films has been studied with an aqueous solution containing CuCl(2), InCl(3) and SeO(2), in terms of composition control of deposited films for the preparation of CuInSe(2). From the relationship between In/Cu or Se/Cu ratio in the bath and that in the deposited film, the ratio of mass-transfer coefficients for In and Cu, k(In)/k(Cu) or for Se and Cu, k(Se)/k(Cu), has been obtained and their dependences on deposition current density or stirring of the solution have been studied. The rate-determining step in the deposition process, reaction or diffusion, has been also discussed. By employing the stirring, a remarkable improvement, by a factor of 3, is attained for run-to-run and position-to-position fluctuation of In/Cu ratio in the films. X-ray diffraction patterns show that CuInSe(2) is contained in as-deposited films.