Electrical and optical properties of CdS films electrodeposited from diethylene glycol solutions containing cadmium salts and molecular sulfur were investigated. Polycrystalline CdS films were grown on glass substrate with conducting indium tin oxide(ITO) by cathodic electrodeposition. The structure, electrical and optical properties of the depositied CdS films are strongly dependent on the nature of the deposition condition. The average size of the plate-shape grains of the CdS films having a prefered (101) axis orientation was 0.1㎛∼0.5㎛, and the adhesion to ITO was good. The optical band gap of the as-deposited CdS films was in the range from 2.56eV to 2.75eV, but the heat-treated CdS films was from 2.46eV to 2.63eV depending on deposition conditions. The optical transmittance was ∼80%. Electrical resistivity of the as-deposted CdS films varied from $10^4$ to 20Ωcm depending on the deposition condition. The carrier density of the as-deposited CdS films ranged from $10^{14}$ to $10^{16}cm^{-3}$. Electrical resitivity is interpreted in terms of a two dimensional versions of the grain boundary barrier model.
