The C—V and G/ω—V Electrical Characteristics of 60Co γ-Ray Irradiated Al/Si3N4/p-Si (MIS) Structures

Abstract

The influence of 60Co (γ-ray) irradiation on the electrical characteristics of Al/Si3N4/p-Si (MIS) structures is investigated using capacitance-voltage (C—V) and conductance-voltage (G/ω—V) measurements. The MIS structures are exposed to a 60Co γ radiation source at a dose of 0.7 kGy/h, with a total dose range of 0–100 kGy. The C—V and G/ω—V properties are measured before and after 60Co γ-ray irradiation at 500 kHz and room temperature. It is found that the capacitance and conductance values decrease with the increase in the total dose due to the irradiation-induced defects at the interface. The results also indicate that γ radiation causes an increase in the barrier height ΦB, Fermi energy EF and depletion layer width WD. The interface state density (Nss), using the Hill-Coleman method and dependent on radiation dose, is determined from the C—V and G/ω—V measurements and decreases with an increase in the radiation dose. The decrease in the interface states can be attributed to the decrease in the recombination centers and the passivation of the Si surface due to the deposition insulator layer (Si3N4). In addition, it is clear that the acceptor concentration NA decreases with increasing radiation dose. The profile of series resistance Rs for various radiation doses is obtained from forward and reverse-biased C—V and G/ω—V measurements, and its values decrease with increasing radiation dose, while it increases with increasing voltage in the accumulation region