STM study of titanium silicide nanostructure growth on Si(1 1 1)-(19×19) substrate

We have performed an STM/STS study of titanium silicide nanostructures grown on Si(1 1 1)-(19×19) substrate by Ti evaporation and post-deposition annealing. The (19×19) reconstruction was induced by Ni doping. The reaction between the deposited material and the substrate at 220 K was radically different from that observed in the case of the standard Si(1 1 1)-(7 × 7) substrate, as evidenced by the different evaporation time necessary to obtain a comparable coverage of the surface. The annealing was accomplished by direct heating of a crystal sample (up to 520 K, 670 K and 970 K). Measurements showed that coalescence of Ti nanoislands began between 520 K and 670 K. Annealing above 900 K led to alloying of Ti, Ni and Si. As a consequence, Si(1 1 1)-(7 × 7) reconstruction occurred at the cost of Si(1 1 1)-(19×19).