Oxide charge trapping and interface trap generation by hot carrier stress was studied with x-ray irradiated metal-oxide-semiconductor field-effect transistors. Although the threshold voltage and transconductance recovered after a hydrogen anneal at 450°C, the irradiated and annealed devices were more susceptible to damage under hot carrier stressing, both at the Si/SiO 2 interface and in the oxide bulk. The latent damage was quantified using the various gate voltage hot carrier stresses. It is found that most of the latent damage is related to oxide hole traps and interface traps. Electron trapping is present, but is less significant.