60Co gamma irradiation effects on electrical characteristics of Al/Y2O3/n-Si/Al capacitors

Al/Y2O3/n-Si/Al capacitors were irradiated by using a 60Co gamma ray source and a maximum dose up to 8.4 kGy. The effect of an annealing treatment performed at 600 or 900 °C on the yttrium oxide (Y2O3) films was investigated by XRD and Raman spectroscopy. High-frequency capacitance–voltage (C–V) and conductance–voltage (G–V) measurements as well as quasi-static measurements of the MOS structures were analysed. The annealing improves the crystalline state of the Y2O3 thin film material and decreases the values of the flat-band voltage and of the interface trap level density indicating an improvement of the electrical properties of the interface thin film–substrate. But at this interface, the formation of an yttrium-silicate layer was also evidenced. After gamma irradiation, the values of the flat-band voltage and of the interface trap level density related to the Al/Y2O3/n-Si/Al structure increase and especially for the structure made with the materials annealed at 900 °C for 1 h. In that case, the structure is very sensitive to a gamma irradiation dose up to 8.4 kGy.