Epitaxial growth of silicon nanowires using an aluminium catalyst

Abstract

Silicon nanowires have been identified as important components for future electronic and sensor nanodevices¹. So far gold has dominated as the catalyst for growing Si nanowires via the vapour–liquid–solid (VLS) mechanism^2,3,4,5. Unfortunately, gold traps electrons and holes in Si and poses a serious contamination problem for Si complementary metal oxide semiconductor (CMOS) processing. Although there are some reports on the use of non-gold catalysts^6,7,8,9 for Si nanowire growth, either the growth requires high temperatures and/or the catalysts are not compatible with CMOS requirements. From a technological standpoint, a much more attractive catalyst material would be aluminium, as it is a standard metal in Si process lines. Here we report for the first time the epitaxial growth of Al-catalysed Si nanowires and suggest that growth proceeds via a vapour–solid–solid (VSS) rather than a VLS mechanism. It is also found that the tapering of the nanowires can be strongly reduced by lowering the growth temperature.