Arrays of Si cones prepared by ion beams: growth mechanisms

Arrays of uniformly distributed Si cones with controlled orientations are fabricated on Si substrates by an ion beam technique. The axes of produced Si cones are well aligned with the direction of ion beams. Each cone essentially consists of a metal containing tip and a single crystalline Si base with the crystallographic orientation identical to the Si substrate. TEM studies show tapered pit interface between the tip and the base, visualizing the ion impinging process. The tip comprises tetragonal MoSi2, domains of Mo-modulated Si ordered superstructures and a few Mo nanoparticles. Experimental evidence indicates that the cone formation follows the left-standing model. Since the cones progressively are sharpened with the elapsed time of their formation, they might develop into whiskers if the ion bombardment and supply of sputtered metal clusters are prolonged. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim