Self-organization of cobalt-silicide nanoislands on stepped Si(111) as a function of growth method

When silicides, such as CoSi2, are grown in the form of nanoislands they frequently exhibit nanometer size effects, which can be useful for single electron devices. For such devices, however, lateral self-organization is required. In this work, step-aided self-organization of CoSi2 nano-islands is demonstrated on a vicinal (stepped) Si(111) substrate. Straight and equidistant steps or step-bunches are routinely obtained on the vicinal Si(111), creating almost ideal template for self-organization. Two growth methods were examined: solid-phase epitaxy (SPE), where Co was deposited at room temperature and annealed to promote silicide formation, and reactive deposition epitaxy (RDE) where Co was deposited at elevated temperature. While the latter did not result in any noticeable ordering, due to instantaneous reaction with Si in course of deposition, the former lead to preferential occupation of step-bunch sites by the silicide nanoislands. Furthermore, self-limiting growth caused narrow distribution of island sizes and island-island separation distances.