Physica Status Solidi (C) Current Topics in Solid State Physics, vol.10, no.7-8, pp.1107-1110, 2013 (Scopus)
Optical constants of CdS:O window layers for solar cells were studied as a function of the oxygen content. The CdS:O thin films were deposited on glass substrates in the presence of oxygen at 0, 2, 3 and 5% values of O/Ar ratio by rf magnetron sputtering. Ellipsometric measurements on CdS:O thin films were carried out over 0.75-6.0 eV photon energies at room temperature. Optical constants were determined by using a the best-fit dispersion model. Broadening of spectral features of the obtained optical constants is found to increase with increasing O/Ar ratio. Besides, the CdS:O films grown at 100 °C as compared to those grown at 200 °C exhibit increased spectral broadening. In fact, almost complete smearing of band gap spectral feature is observed for CdS:O films deposited at 5% value of O/Ar ratio, resulting in appreciable transparency of the films in a spectral range above the energy gap of CdS. This, in turn, leads to an increased carrier collection in the UV spectral range and allows to considering CdS:O film as a candidate for improved window-layer material for solar cell application. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.