G. Piccitto

Solid phase phosphorous activation in implanted silicon by excimer laser irradiation

The activation mechanism in phosphorous implanted silicon under excimer laser irradiation is investigated. The activation efficiency in the solid phase has been measured in a wide range of irradiation conditions, tuning the laser fluence in the sub-, partial, and total melting regime. Moreover, fixing the fluence, the activation as a function of the shot number has been analyzed. The total active fraction varies by several orders of magnitude and shows a complex trend depending on the process conditions. Our model, based on the interaction between defects and the active/inactive impurities, explains this scenario. In particular, it predicts experimental P active profiles, thus demonstrating that the status of the defect system rules the activation phenomenon, where the coupling between dopant and defect clusters at the early irradiation stage plays a crucial role.

Electronic collective transport in disordered array of C49-phase TiSi2 nanocrystals in Si

We have studied the longitudinal electronic collective transport properties in a disordered array of TiSi2 nanocrystals (with surface density of 1012cm−2) embedded in Si polycrystalline matrix as a function of temperature. The system is characterized by a high degree of disorder compared to the standard disordered nanocrystal array usually studied in the literature. Despite of this fundamental difference, we demonstrate that the theoretical models used to describe the collective electronic transport in standard systems are adequate to describe the electrical behavior of such a “nonstandard” system. In particular, we show that two different conduction regimes, separated by a crossover temperature T*, exist: at T<T* the collective electronic transport is characterized by a Coulomb blockade phenomenon (with a positive threshold voltage) and a scaling behavior characteristic of a two-dimensional transport. Above T*, at low field, a thermally activated conduction mechanism is evident, and at high field the col...