Solution-grown CdS layers for polycrystalline-thin-film solar cells

Solution growth of CdS layers was investigated for use as heterojunction partner in CuInSe/sub 2/ and CdTe polycrystalline-thin-film solar cells. Morphological and optical properties improved significantly when buffer solution was used. Cadmium acetate was found to be preferable as a cadmium ion source as compared to cadmium chloride. Optimum conditions for slow ion-by-ion growth on SnO/sub 2/:F coated glass substrates of conformal CdS 500-2600 /spl Aring/ thick layers with direct bandgap of /spl sim/2.40 eV were cadmium salt concentration Q in the range 0.001-0.003 M, thiourea concentration 5/spl times/Q, buffer solution concentration 20/spl times/Q, pH in the range of 9.0-9.5, deposition temperature of 80-85/spl deg/C and deposition time of 13-30 min. Heterogeneous growth on the substrate was found to depend critically on the availability of nucleation sites.< >