Epitaxy in solid-phase thin film reactions: Nucleation-controlled growth of iron suicide nanostructures on Si(001)
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special type of epitaxial growth appears during solid-phase thin film reactions, where the reaction product grows epitaxially on the substrate. Some metal silicide layers and nanostructures are known to develop such epitaxial structures. In this study, iron silicide was used to study the effect of the growth mode on the epitaxial growth. Strain-induced, self-assembled iron silicide nanostructures were grown on Si(001) substrates by electron gun evaporation of 1.0 nm iron and subsequent annealing at 500–850 °C for 60 min. The growth processes were checked by reflection high-energy electron diffraction, and the formed structures were characterized by scanning electron microscopy and optical microscopy. The iron silicide nanostructures were oriented in square directions epitaxially fitting to the surface of Si(001). The shape and size of the nanostructures depended on the annealing temperature. In some cases, the nanoparticles were arranged in circles. This might be the direct consequence of a nucleation-controlled type transition of iron monosilicide to iron disilicide phase at nanoscale. I. INTRODUCTION
The fabrication of artificial low-dimensional structures is one of the most challenging research fields in the solidstate technology. These nanoobjects are prepared by physical and chemical or by combined methods and they have attracted great interest due to their scientific peculiarity and technical significance. Nanostructures are applied both in bulk and low-dimensional materials for composite materials, energy production, catalysis, optoelectronics, nanomagnetic materials, and for biomedicine.1 One of the most challenging methods of nanostructure production is the phenomenon of self-assembly, which has been applied in the case of compound and group IV semiconductors and a wide range of material and substrate combinations.2 During self-assembly phenomena, the natural laws are used as instruments to produce the nanostructures. The strain induced self-assembled growth is a basic physical method for the preparation of nanostructures. In the case of thin film growth, three basic modes may occur, depending on the surface and interface free energies: layer-by-layer growth (Frank-van der Merwe type), island growth (Volmer-Weber type), several complete monolayer formation, and subsequently three-dimensional clusters growth on the top of the first monolayers (Stranski–Krastanov type).3 The Stranski–Krastanov growth occurs mainly during epitaxial growth of films on monocrystalline substrates, as a consequence of lattice distortions due to lattice mismatch. a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2013.64 1724
J. Mater. Res., Vol. 28, No. 13, Jul 14, 2013
http://journals.cambridge.org
Downloaded: 12 Apr 2015
The general concept of domain matching epitaxy is applicable across the whole misfit scale.4 During the growth of strained layers, the film is able to remain planar up to a critical thickness that can be calculated based on the misfit between the strained layer and film accord
