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1058-JJ03-30

Pulsed PECVD Growth of Silicon Nanowires on Various Substrates David Parlevliet, and John C. L. Cornish Physics & Energy Studies, Murdoch University, EEPE, DSE, Murdoch University, South St, Murdoch WA 6150, Murdoch, 6150, Australia ABSTRACT Silicon nanowires with high aspect ratio were grown using PPECVD and a gold catalyst on a variety of different substrates. The morphology of the nanowires was investigated for a range of crystalline silicon, glass, metal, ITO coated and amorphous silicon coated glass substrates. Deposition of the nanowires was carried out in a parallel plate PECVD chamber modified for PPECVD using a 1kHz square wave to modulate the 13.56MHz RF signal. Samples were analyzed using either a Phillips XL20 SEM of a ZEISS 1555 VP FESEM. The average diameter of the nanowires was found to be independent of the substrate used. The silicon nanowires would grow on all of the substrates tested, however the density varied greatly. It was found that nanowires grew with higher density on the ITO coated glass substrates rather than the uncoated glass substrates. Aligned nanowire growth was observed on polished copper substrates. Of all the substrates trialed, ITO coated aluminosilicate glass proved to be the most effective substrate for the growth of silicon nanowires. INTRODUCTION Silicon nanowires can be produced by techniques compatible with or already used in the thin film and semiconductor manufacturing industries making them attractive for applications in advanced photovoltaics. Silicon nanowires are often grown via the Vapour Liquid Solid (VLS) mechanism as first proposed by Wagner and Ellis 1. Plasma Enhanced Chemical Vapor Deposition (PECVD) is a widely used technique for the growth of semiconductor thin films. When used with substrates covered with a metal catalyst such as gold, PECVD has been used to produce silicon nanowires and is known to improve their deposition rate 2. A further modification of PECVD uses a square wave signal to produce Pulsed PECVD (PPECVD). We have previously shown 3 that the use of PPECVD improves nanowire density and overall sample coverage in comparison to PECVD. Silicon nanowires have been produced using a variety of substrates, although most interest is devoted to what is being grown, the substrate used can affect the ultimate usefulness of the silicon nanowires. The appropriate choice of crystalline silicon substrates can affect the direction of growth of the nanowires in relation to the substrate by using an epitaxial growth mechanism 4. To take advantage of the epitaxial growth mechanism the native oxide must be removed from the silicon substrate. The treatment of the substrates with an HF etch to remove the native oxide layer before the addition of a gold layer is critical for epitaxial growth. It has also been found that the formation of SiO2 on the gold deposited on silicon (111) substrates can have a detrimental effect on the epitaxial growth of silicon nanowires 5 , hence was recommended that the silicon oxide over layer be removed from the gold befo