Optical characterization of non-annealed CdS: O films for window layers in solar cells


Kitano A., Shim Y., Wakita K., Khalilova K., MƏMMƏDOV N., Bayramov A., ...daha çox

Physica Status Solidi (C) Current Topics in Solid State Physics, vol.10, no.7-8, pp.1107-1110, 2013 (Scopus) identifier

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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.