Nanostructure, optical and electrical response of gamma ray radiated PdS/p-Si heterojunction

The palladium sulfide/p-type Si (PdS/p-Si) heterojunction was used to investigate the effects of gamma ray exposure on the structural, optical and current-voltage (I–V) characteristics, for gamma detection. High-quality PdS thin films was deposited onto p-Si substrates and evaluated as active components of the heterojunction. The PdS thin films was prepared using a successive ionic layer adsorption and reaction (SILAR) technique. The samples were then irradiated using a60Co gamma source at dose of up to 100 kGy. X-ray diffraction (XRD) analysis indicated the formation of a tetragonal phase in the PdS thin films, an increase in crystallinity and a decrease in the crystallite size. The distributions of spherical grains on the surfaces of the substrate were observed using a field emission scanning electron microscope (FE-SEM) and energy dispersive X-ray (EDX) analysis was performed to determine the stoichiometric compositions of the PdS thin films. The FE-SEM images revealed the presence of voids after irradiation. Photoluminescence (PL) spectroscopy indicated an increase in the recombination rate of electron-hole pairs after irradiation, and spectral broadening occurred as a function of the gamma dose. The I–V characteristics of the PdS/p-Si heterojunction were investigated before and after irradiation. Changes in the electrical properties of the heterojunctions induced by irradiation, including the saturation current, ideality factor, barrier height, series resistance and shunt resistance, were investigated. The linear electrical responses of the PdS/p-Si heterojunction indicated that they were highly sensitive to gamma radiation. The outstanding electrical and optical responses of the PdS/p-Si heterojunction in accordance with the gamma dose indicated that they could be used for radiation dosimetry.