Solution flow rate influence on ZnS thin films properties grown by ultrasonic spray for optoelectronic application

The aim of this work is to investigate the dependence of ZnS thin films structural and optical properties with the solution flow rate during the deposition using an ultrasonic spray method. The solution flow rate ranged from 10 to 50 mL/h and the substrate temperature was maintained at 450 degrees C. The effect of the solution flow rate on the properties of ZnS thin films was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), optical transmittance spectroscopy (UV-V) and the four-point method. The X-ray diffraction analysis showed that the deposited material was pure zinc sulphide, it has a cubic sphalerite structure with preferential orientation along the (111) direction. The grain size values were calculated and found to be between 38 to 82 nm. SEM analysis revealed that the deposited thin films have good adherence to the substrate surfaces, are homogeneous and have high density. The average transmission of all films is up more than 65% in the range wavelength from 200 to 1100 nm and their band gap energy values were found between 3.5-3.92 eV. The obtained film thickness varies from 390 to 1040 nm. Moreover, the electric resistivity of the deposited films increases with the increasing of the solution flow rate between 3.51 x 10(5) and 11 x 10(5) Omega.cm.