Comparative Study of Gamma Ray and Neutron Radiation on Some Electrical Properties of n-CdSe/p-Si Photodiodes.

Abstract

Cadmium Selenide (CdSe) thin films were prepared on silicon(p-type) substrates using the pulsed laser deposition technique (PLD). They were then annealed at 300 ºC for one hour to get diodes used as a visible light detector. Four diodes were subjected to four different intervals of gamma radiation emitted from the 226Ra source. For comparison, four of these diodes were subjected to four different intervals of neutron radiation using a ( 241Am -10Be) source; the other diodes were kept without exposure to irradiation. I-V measurements studied the electrical properties of these samples. Results of gamma-irradiated devices show that dark current decreases for the irradiated thin films. Forward current under illumination increases when exposed to small gamma radiation values and then decreases with higher exposure values. While the value of reverse current increases with the irradiation. The results of I-V characteristics for neutron irradiation devices show that the value of current under illumination increases when exposed to small values of neutron radiation, then it decreases with higher values of exposure. However, dark current decreases significantly with irradiation. The effect of the gamma and neutron irradiation was clear on the response/recovery period for all irradiated devices. However, it was more profound in the response/recovery time of pristine devices. Also, the photo-responsivity of the pristine device was larger than that of the irradiated devices, and it decreased with increasing absorbed doses of gamma and neutron radiation