Influences of Co-60 gamma-ray irradiation on electrical characteristics of Al2O3 MOS capacitors

Effects of gamma-ray irradiation on the electrical characteristics of Al2O3 MOS capacitors such as barrier height, acceptor concentration, series resistance and interface state parameters have been studied by analyzing capacitance-voltage (C-V) and conductance-voltage (G/omega-V) measurements. The fabricated MOS capacitors were irradiated with gamma-rays at doses up to five grays. C-V and G/omega-V measurements were recorded prior to and after irradiation at high frequency. The results show that the measured capacitance and conductance values decreased with increasing in irradiation dose and C-V and G/omega curves has been shifted toward the negative voltages. Moreover, the series resistance (R (s)) and density of interface states increased with increasing in irradiation dose and density of interface states (D (it)) were calculated as order of 10(12) eV(-1)cm(-2) prior to and after irradiation. Due to presence and variations in the R (s) values, the corrected and the measured C-V and G/omega-V exhibited different behaviors. Therefore other electrical characteristics were assessed from corrected C (c) characteristics. It was observed that acceptor concentration decreased with increasing in barrier height of device due to changes in interface states and diffusion potential.