Structural, Optical and Electrical Properties of Spray Pyrolysis Deposited CdS Films

The n-type cadmium sulfide (CdS) is one of the most promising materials for hetero-junction thin film solar cell applications due to its wide bandgap (2.42 eV). In present communication, the deposition of pure CdS films with hexagonal symmetry by using home-built spray pyrolysis technique and aqueous solutions of CdCl2 and NH2.CS.NH2 as the precursor materials is reported. The films were deposited at the substrate temperatures of 200, 250 and 300 degrees C with UHP nitrogen as a carrier gas and characterized by using X-ray diffraction (XRD), UV-visible spectroscopy and Hall Effect measurement. The structural studies by using XRD showed that the resultant films have strong orientation of CdS crystallites along (101) with hexagonal structure (wurtzite type). The average crystallite size is found to be 17 nm. The UV-visible spectroscopy studies of resultant films showed the optical transmittance equal to approximate to 50% and bandgap is found to be between 2.39 - 2.41 eV. The resistivity and average Hall coefficient are found to be 1.451 X 10(1) cm and - 1.557 X 10(3) cm (3)/C respectively. The resultant films are observed to be good to make a solar cell with CdS as a window layer.