Proton trapping in SiO 2 layers thermally grown on Si and SiC

Abstract

Positive charging of thermal SiO 2 layers on (1 0 0)Si and (0 0 0 1)6H–, 4H–SiC related to trapping of protons is studied using low-energy proton implantation into the oxide, and compared to the trapping of holes generated by 10-eV photons. Proton trapping has an initial probability close to 100% and shows little sensitivity to the annealing-induced oxygen deficiency of SiO 2. In contrast to protons, hole trapping in as-grown SiO 2 shows a much lower efficiency which increases upon oxide annealing, in qualitative correlation with the higher density of O 3Si• defects (E’ centers) detected by electron spin resonance after hole injection. Despite these differences, the neutralization of positive charges induced by holes and protons has the same cross-section, and in both cases is accompanied by liberation of atomic H suggesting that protons account for positive charge in both cases. The rupture of Si–O bonds in the oxide observed upon proton injection suggests, as a first basic step, the bonding of a proton to a bridging oxygen atom in SiO 2 network.