FN tunneling and hot hole (HH) stress induced leakage current (SILC) transient characteristics in thin gate oxide are investigated. Under both stress conditions, the stress induced leakage current obeys a power-law time dependence with different power factor. For HH SILC, the power factor significantly departs from -1. HH SILC is found to have a more pronounced transient effect. The results show that HH SILC can be attributed to positive oxide detrapping and annihilation of positive charge-assisted tunneling current. The latter can be diminished by substrate hot electron injection.