M.Phil. - "Silicon Nanostructures"

During the year 2001-2002, I obtained an M.Phil. on Silicon Nanostructures in the Electronic Devices and Materials group of the Engineering Department of Cambridge University.

We succeeded in growing Silicon nanowires by plasma-enhanced chemical vapour deposition of Silane, catalysed by Gold. The original intention was to use Gallium as a catalyst, but changed to using Gold when it became apparent that Gallium would contaminate the shared apparatus. We succeeded in growing nanowires at low temperatures (400 °C) and pressures (1500 mTorr). The abstract is below, or download the complete version. [PDF format, 7.3 MB].

Silicon Nanostructures - Abstract
Silicon nanowires have great potential in both physics and microelectronics. This research investigates the low temperature methods available for growing nanowires via the radio-frequency plasma-enhanced chemical vapour deposition of silane. The use of gallium was not possible; however the gold-silane vapour-liquid-solid method proved successful for growing thin nanowires. The growth conditions were optimised: the most successful were a 0.5 nm thick layer of gold heated to 400 °C (nominal) at a pressure of 1500 mTorr for 90 minutes. A gas flow of 80 sccm of pure silane was used and decomposition was assisted by 6 W of RF plasma. This yielded dense, crystalline silicon nanowires up to 30 µm in length and as small as 10 nm in diameter.

My supervisor was Professor John Robertson, and I gratefully acknowledge the assistance of many others, especially Dr Andrew Flewitt and Dr Stephan Hofmann.

This thesis was completed in September 2002, and was written with the excellent, and easy-to-use LyX editor (a "WYSIWYM" GUI for TEΧ), which I would highly recommend. It is dedicated to Claire Pike. The copyright notice is extremely liberal, which is my response to the frustrations of using online journals, with inaccessible, non-searchable (by google), or subscription-only content - and which, I feel, do significant harm to Scientific Co-operation. At least my contribution, such little as it is, will not be locked away from the rest of humanity!

Copyright © 2002 Richard John Neill. Permission is hereby granted to copy, distribute and/or modify this document in any way provided that this notice is preserved. This is to ensure that the contents of this thesis remain freely available to all.

Update: Stephan Hofmann wrote a 2003 paper in the Journal of Applied Physics, in which this work played a part: this paper is:

S. Hofmann, C. Ducati, R. J. Neill, S. Piscanec, A. C. Ferrari, J. Geng, R. Dunin-Borkowski and J. Robertson, 'Gold-catalyzed growth of silicon nanowires by plasma enhanced chemical vapor deposition', J App Phys 94 6005 (2003)
[The paper can also be downloaded (without subscription) directly from Stephan's webpage.]