The transition of a charge transport mechanism in ultrathin (2-3 nm) S
iO2 films from Fowler-Nordheim injection to direct tunneling was found
to result in the enhancement of a charge-to-degradation from similar
to 10(3) to similar to 10(7) C/cm(2). Tunnel MOS structures were exami
ned at high current density (200-1000 A/cm(2)).