Recovery of threshold voltage due to high drain or gate voltage and the effects of hot-carrier stressing on the drain breakdown voltage of MOSFET's have been studied. High oxide field causes slow recovery through tunneling detrapping of electrons in both p- and n-MOSFET’s. For n-MOSFET’s, a mechanism of fast recovery is low-level hole injection at high VD. Hot-carrier stressing at high VG causes the drain breakdown voltage to decrease (walk-in). This results in enhanced hole injection thus increasing the rate of subsequent recovery of V,. The breakdown voltage increases then decreases when stressed at low gate voltages.