DETERMINATION OF OPTICAL CONSTANTS OF THERMALLY EVAPORATED CdS_xSe_1-x THIN FILMS USING ONLY TRANSMISSION SPECTRA

LAILA. I. SOLIMAN and ALAA M. IBRAHIM^*

Solid State Physics Laboratory, National Research Centre, Cairo, Egypt
^*University College for Girls, Ain Shams University, Physics Department, Cairo, Egypt

Received 12 August 1997

A procedure to calculate the optical constants and thickness of thin films, using only data from the transmission spectra, has been employed in the case of cadmium sulfo-selenide films prepared by thermal evaporation. Using this technique, the calculated thickness was found to an accuracy ranging between 1.0 and 3.0% compared with other methods. The refractive index and the absorption coefficient, as a function of composition (i.e. value of x) have been derived using this technique that proved to be very accurate. CdS_xSe_1-x films have a direct energy gap for films of various composition, and the values of the energy gap were found to increase when increasing the content of sulphur (x).

UDC 538.958
PACS number: 78.66.-w

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