Effect of thickness on the structural, optical and electrical properties of MW-CBD CdZnS thin films

B Vidhya,S Velumani

doi:10.1109/iceee.2009.5393317

Abstract

Thin films of CdZnS have found extensive applications in various optical, electrical and optoelectronic devices. In the present work CdZnS (Cadmium Zinc Sulphide) thin films have been deposited by a simple, inexpensive and rapid synthesis route, microwave-assisted chemical bath deposition (MW-CBD). The bath solution is composed of Cadmium Sulphate, Zinc Sulphate, thiourea, ammonium Sulphate and ammonia. The concentration of ZnSO 4 is maintained at Y= [ZnSO 4 ]/ {[CdSO 4 ] + [ZnSO 4 ]} for Y=0.3. The deposition has been carried out for five different radiation time from 60s to 180s, in steps of 30s. X-ray diffraction (XRD) indicates the hexagonal structure (002) peak at 2¿ =26.59 o for the as-deposited CdZnS thin films. The grain size, dislocation density and strain in the deposited films have been determined. SEM image gives the morphology, size and shape of particles in the deposited CdZnS thin films. EDX results show that the composition of the film is maintained irrespective of radiation time. Optical transmission measurements reveal that the films show good transparency over 80% in the wavelength region of 500-1100 nm. The band gap of CdZnS thin films is found to be around 2.6 eV. Sheet resistance of the samples calculated by using Van der Pauw technique is in the order of 10 6 ¿ /Sq. Resistivity of the films is in the order of 10 1 to 10 2 ¿-Cm.

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