Please use this identifier to cite or link to this item: https://doi.org/10.1016/j.susc.2012.07.004
Title: Growth dynamics of low-dimensional CoSi 2 nanostructures revisited: Influence of interface structure and growth temperature
Authors: Ong, B.L.
Ong, W.
Foo, Y.L.
Pan, J.
Tok, E.S. 
Keywords: Growth dynamics
Si surfaces
Silicides
STM
Wires
Issue Date: Nov-2012
Citation: Ong, B.L., Ong, W., Foo, Y.L., Pan, J., Tok, E.S. (2012-11). Growth dynamics of low-dimensional CoSi 2 nanostructures revisited: Influence of interface structure and growth temperature. Surface Science 606 (21-22) : 1649-1669. ScholarBank@NUS Repository. https://doi.org/10.1016/j.susc.2012.07.004
Abstract: The growth of cobalt silicide nanostructures on clean Si(001) was studied using scanning tunnelling microscopy and transmission electron microscopy. Two types of CoSi 2 nanostructures, flat and ridge-type islands, were formed when 0.1 ML Co was deposited onto clean Si(001) between 500 °C and 800 °C. These islands form elongated islands along [110] directions and grow into the Si-substrate within the temperature range. The formation of the two types of islands arises primarily due to the type of CoSi 2{111}- Si{111} interface formed between the island and the substrate. Flat islands are bound by CoSi 2{111}-Si{111} Type-A interfaces such that CoSi 2(001)//Si(001) and CoSi 2[001]//Si[001]. Ridge islands, on the other hand, are bound by a "twinned" CoSi 2{111}- Si{111} Type-B interface such that CoSi 2(221)//Si(001) and CoSi 2 [11̄0] //Si[11̄0]. This leads to the formation of three less energetically-favourable interfaces: CoSi 2(1̄1̄1̄ )-Si(115̄), CoSi 2(1̄1̄2̄)-Si(112̄), and CoSi 2(1̄1̄5̄)-Si(111̄). Analysis of the interfacial energies through dangling bond counting per interfacial area for each interface shows that the formation of the Type-B interface is energetically more favourable compared to the rest of the interfaces. As a result, the island elongates preferentially along the Type B interface leading to the formation of long nanowires with large length-width aspect ratio of 20:1. However, this formation is only achieved at high growth temperatures due to the presence of corner-barriers constraining the growth at low temperatures. Conversely, flat islands are slightly elongated at low growth temperatures with aspect ratio reaching 7:1 at 650 °C. As temperature increases towards 760 °C, they are brought closer to equilibrium and hence become less elongated with aspect ratio reduced to 1.6:1. © 2012 Elsevier B.V. All rights reserved.
Source Title: Surface Science
URI: http://scholarbank.nus.edu.sg/handle/10635/96753
ISSN: 00396028
DOI: 10.1016/j.susc.2012.07.004
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