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This work presents polarity effects during Fowler-Nordheim electric field stress on defect generation in thin silicon dioxide films and at the interface with the silicon. The results show a dissymmetry on interface state kinetic generation and the presence of a critical injected fluence at which the dissymmetry is reversed. For injected fluences lower than this critical charge, the density of interface states created under positive gate bias is higher than that generated under negative bias, and if the injected charge is higher than the critical fluence the dissymmetry is reserved. However, the net oxide positive charge generated under positive bias is always lower than that created under negative bias.

The possibilities of tunneling spectroscopy in metal-oxide-degenerate silicon with a very thin oxide layer have been studied at low temperature by measuring the first and second derivatives of the current-voltage characteristics. Silicon phonon structures are easily detectable whereas high level features induced by molecular vibrations are hardly seen. The aim of this paper is to show that the main difficulty lies in the metal-oxide-semiconductor junction band structure itself.

Tunnelling phenomena were studied in two kinds of specimens: samples A, essentially metal—silicon junctions, featured a thin silicon oxide transition layer; samples B were prepared by the anodization of silicon in pure water. I, dI/dV and d2I/dV2vs. V curves were obtained at liquid helium temperature. For both specimens, the general shapes of the curves were in agreement with the theoretical prediction. Phonon fine structure was obtained. Moreover, for samples A, a zero-bias anomaly phenomenon, indicating the presence of metal particles in the oxide, as well as other structures, due to traps, were observed. The absence of such structures and of a zero-bias anomaly for samples B and the appearance of phonon structures, in spite of the considerably smaller amount of doping, are indications of a good quality oxide. This was in accordance with capacitance measurements made on thicker oxide obtained by the same process. These experiments show that inelastic electron tunnelling spectroscopy can be used as a valuable tool for the study of very thin silicon oxide layers in electron devices.