Orientation dependence of interface-trap transformation

Immediately after radiation or hot-electron damage, an interface-trap peak above midgap ( approximately E/sub v/+0.75 eV) invariably appears in MOS capacitors. This peak (designated peak-1), along with its background, continuously changes with time after damage. Three different regimes have been identified: (1) latent generation, (2) interface-trap transformation, and (3) room-temperature annealing. In the present work, the orientation dependence of the interface-trap transformation process is discussed. For samples made on [100] substrates, peak-1 gradually converts into a second peak below midgap, resulting in a double-peak interface-trap distribution. For samples made on [111] substrates, the most salient feature is the gradual shift of the energy position of peak-1 toward the valence band, and eventually a single peak residing below midgap is observed. No discernible double-peak distribution has been found in [111] samples. Results on [110] samples are qualitatively similar to those on [111] samples, whereas [311] samples are similar to [100] samples. The [111] results are interpreted in terms of the atomic relaxation of the dangling-bond defect at the [111]Si/SiO/sub 2/ interface.>