Chemistry of CdS/CuInSe2 structures as controlled by the CdS deposition bath

Electrodeposited CuInSe2 samples have been used as substrates for CdS growt h from alkaline solutions where the ratio of thiourea, SC(NH2)(2) or TU, to cadmium sulfate, CdSO4, has been varied systematically from 10 to 100. Ana lysis of the CdS/CuInSe2 surface and interface chemistry as a function of t he CdS bath deposition conditions has been performed by X-ray photoelectron spectroscopy. An increase in the CuInSe2 surface coverage, without appreci able CuInSe2 chemical modifications, can be obtained by increasing the thio urea to cadmium sulfate proportion in the CdS growth solution. As this [TU] /[CdSO4] ratio increases, the proportion of Cd(OH)(2) and CdSO4 secondary p hases detected on the CdS/CuInSe2 samples decreases with respect to water a nd the main CdS compound, but carbonate and cyanamide impurities incorporat ion increases at the near-surface region. (C) 2001 The Electrochemical Soci ety.