DEGRADATION OF MOS TUNNEL STRUCTURES AT HIGH-CURRENT DENSITY

The stability of tunneling-thin (2-3 nm) SiO2 films during prolonged f low of high-density currents (10(2) - 10(3) A/cm(2)) was investigated. A sharp increase in the charge which a tunneling MOS structure is cap able of transmitting without degradation on switching from Fowler-Nord heim injection to direct tunneling (10(3) C/cm(2) and 10(7) C/cm(2), r espectively) was observed. The degradation of SiO2 films was investiga ted using Al/SiO2/n-Si/p(+)-Si thyristor structures with a positive bi as on the semiconductor, i.e., with reverse bias of the MOS structure. The use of these devices accounted for the uniformity of the current distribution over the area and made it possible to monitor the state o f the insulator layer by measuring the device gain in the phototransis tor mode. (C) 1998 American Institute of Physics.