Preparation and characterization of CdS thin films

Abstract

In this work we report the structural, optical and electrical properties of CdS thin films prepared by chemical bath deposition (CBD) under the effect of solution temperatures. The solution temperatures used vary between 55 and 75 °C. The XRD patterns show that the films have a hexagonal phase with a preferential (002) orientation. The structural parameters such as the grain size, dislocation density and strain are calculated. The transmission spectra, recorded in the UV visible range, reveal a high transmission coefficient (85%) of the prepared films and an optical band gap values of 2 - 2.4 eV. The electrical measurements show that the dark conductivity values increase from 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-7</sup> to 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> (Ω.cm) <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> at higher temperature (Ts >; 65°C). It is found that the photoconductivity of the deposited films is two to five decades larger than the dark conductivity, and the photoconductivity to the dark conductivity ratio obtained at 3000 Lx vary from 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> to 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> . From these results we inferred that the elaborated CdS thin films exhibit good properties intended for solar cell window layers.