Complete thin film solar cells have been fabricated by physical vapour deposition of CdTe onto chemical-bath-deposited CdS supported on a commercial SnO2/glass substrate. Cell I-V characteristics were measured under AM 1.5(G) illumination. Energy dispersive X-ray analysis was used to measure the average stoichiometry. Nuclear Reaction Analysis was used to measure the degree of S diffusion within the CdTe thin films. X-ray diffraction was used to determine the lattice parameter of the CdTe. Results showed the CdTe films deposited at low deposition rates (<2 nm s(-1)) exhibited greater S diffusion after a partial recrystallisation during annealing. Higher CdTe deposition rates correlated to increased Te concentration for the as-deposited films, significantly reduced during annealing. (C) 2002 Elsevier Science B.V. All rights reserved.