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 10(12) cm(-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 collective electron transport is again characterized by a two-dimesional scaling behavior with an effective negative threshold voltage. (c) 2007 American Institute of Physics.