Modifications on CdS thin films due to low-energy ion bombardment

Abstract

In the present study, thin films of cadmium sulfide (CdS) of thickness ∼ 300 nm were used to bombard with 350 keV argon (Ar4+) ions. The films were deposited on glass by thermal evaporation method. The irradiation was performed for ion fluences 1×1015, 3×1015 and 1×1016 ions/cm2 at normal incidence to study the modification in surface nanostructures as well as structural and optical properties of the films. The pristine and irradiated films were characterized by X-ray diffractometer, UV–visible spectroscopy and atomic force microscopy (AFM). The bombarded surface shows the evolution of structures from circular grains of wider size distribution to smaller grains (with a narrow distribution of sizes) with an increase in the ion fluence. X-ray diffraction of the pristine film shows the polycrystalline nature of the film with most intense peak at 26.49° along the (002) plane in a hexagonal phase. The crystallite size was found to be between 29 and 35 nm. The band gap of the pristine film was observed as 2.24 eV. The low-energy bombardment has resulted in the relaxation of strain and in an improvement in the crystallinity of the CdS films.