Co-60 gamma irradiation influences on device characteristics of n-SnO2/p-Si heterojunction diodes

Gamma irradiation induced modifications on the structural, morphological, and electrochemical characteristics of the n-SnO₂/p-Si heterojunction diodes incorporating their influences on the electrical properties of diode have been systematically studied. The results indicate that irradiation exposure improves the crystallographic structure of the SnO₂ layer as expected but, reduce the device capacitance due to changes in the dielectric characteristics of the SnO₂. In addition, the surface roughness of the SnO₂ thin films become smoother as the irradiation exposures enhanced. On the other hand, low dose irradiation exposure generates the local heating that neutralizes a portion of the dangling bonds which are especially close to the interface between SnO₂ and Si. Hence, interface state density decreases after low dose irradiation exposure. However, high irradiation doses create a large number of oxygen vacancies and interstitial defect. These generated defect sites lead to changes on the barrier potential and conduction mechanism of the diode. It can be concluded that complex irradiation induced mechanism has been observed for SnO₂/Si heterojunction diodes. Any irradiation-induced changes on the film structures and electrochemical parameters directly affect the electrical responses of the diodes.