Electron avalanche injection has been used to study electron trapping and positive charge generation in thin (10–30 nm) ammonia-annealed silicon dioxide films as a function of process conditions. It is found that the electron traps induced by nitridation are characterized by a capture cross section of ∼10−16 cm2 and by a density which increases with nitridation temperature and time. These results suggest that the traps are due to the nitrogen itself at oxygen sites. Even though electron traps in conventional oxides enhance the positive charge generation rate, the turn-around effect in nitrided oxides is greatly reduced or completely eliminated under severe nitridation conditions. The process dependence of the turn-around effect suggests that the nitrogen near the interface is mainly responsible for this effect.

A field effect transistor (FET) has been fabricated with the hexamer of thiophene (asexithienyl) in order to assess the performance of such electronic devices based on an organic material. Particular emphasis has been given to the determination of the origin of the instability in the electrical performance. From this study it is confirmed that charged species, possibly chemical impurities present in the processed material, can migrate through the film under an applied electric field, even at room temperature. KEYWORDS a-sexithienyl field effect transistor

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