Gamma dose dependent structural, optical and current-voltage characteristics of CdS/p-Si heterojunction

Heterojunction of CdS/p-Si were fabricated by deposited the cadmium sulfide (CdS) thin films on p-type silicon (Si) substrates using successive ionic layer adsorption and reaction (SILAR). To study the nano-structural, optical and current–voltage (I–V) characterization, the heterojunction was irradiated by gamma radiation with different dose in the range of 0–100 kGy. The X-ray diffraction results showed that CdS thin film has a nano-crystalline hexagonal structural with reduction in crystallinity. An increase in gamma irradiation dose the deposition temperature enhances crystallite sizes of CdS thin film. Field emission scanning electron microscope represented that the grain size was increased with increasing the gamma irradiation dose. The diffuse reflectance indicated that the CdS thin energy band gap shifted to lower energy as of function of gamma dose. The electrical parameters were calculated from the I–V characterization carried out in dark at room temperatures. From these measurements it is inferred that the forward current increases with increasing gamma dose whereas the turn on voltage drops from 4.38 V to 3.64 V. The ideality factor of the n-CdS/p-Si heterojunction is greater than unity, whereas the optimized values of series resistance, barrier height and saturation current for the CdS/p-Si changed with radiation because of density of defect induced by gamma and charge carrier trapping on interface layer. •Investigation of gamma induced effects on CdS/p-Si heterojunction prepared by SILAR.•The reduction in crystallinity of the structure of the gamma irradiated CdS/p-Si heterojunction.•Gamma irradiated CdS/p-Si heterojunction indicate the band gap shifted to lower energy as of function of gamma dose.•Optical and electrical response is a good sign to use CdS/p-Si heterojunction for dosimetry application.