The electron trapping behavior of SiO2 has been measured as a function of thickness at 295 and 77 °K. The devices used were metal-oxide-semiconductor devices with the SiO2 grown thermally. The results indicate bulk traps are dominant at 295 °K and traps associated with the Si-SiO2 interface are dominant at 77 °K. The effect of processing conditions was also studied and the optimum conditions are different for the two temperatures used for the measurements. These observations have been verified using a photo I-V technique. The generation of donor states in the SiO2 near the Si-SiO2 interface was observed as a result of the electron current through the SiO2.