Degradation effects in the one-band-tunneling Au/CaF2/n-Si(111) MIS structures

High quality Au/CaF2/n-Si(111) metal–insulator–semiconductor structures with thin (< 2.5 nm) epitaxial fluorite layers were fabricated. Damage of such structures due to electrical overload has been investigated in this work. Current–voltage characteristics of these structures before and in process of degradation are measured. A mechanism explaining the pronounced breakdown at reverse bias is suggested. This mechanism relies on the potentially possible bistability arising from the one-band character of tunneling in the studied devices. Some comparisons with the degradation scenario in SiO2-based samples are made. Wear-out fields for CaF2 films are estimated. The changes in behaviour of fresh and damaged structures under visible light irradiation are treated.