R Koester et al 2010 Nanotechnology 21 015602 doi:10.1088/0957-4484/21/1/015602
R Koester1, J S Hwang2, C Durand1,3, D Le Si Dang2 and J Eymery1,4
Show affiliationsA catalyst-free method for growing self-assembled GaN wires on c-plane sapphire substrates by metal–organic vapour phase epitaxy is developed. This approach, based on in situ deposition of a thin SiNx layer (~2 nm), enables epitaxial growth of c-oriented wires with 200–1500 nm diameters and a large length/diameter ratio (>100) on c-plane sapphire substrate. Detailed study of the growth mechanisms shows that a combination of key parameters is necessary to obtain vertical growth. In particular, the duration of the SiNx deposition prior to the wire growth is critical for controlling the epitaxy with the substrate. The GaN seed nucleation time determines the mean size diameter and structural quality, and a high Si-dopant concentration promotes vertical growth. Such GaN wires exhibit UV-light emission centred at ~350 nm and a weak yellow band (~550 nm) at low temperature.
68.55.A- Nucleation and growth
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, etc.)
Condensed matter: electrical, magnetic and optical
Issue 1 (8 January 2010)
Received 18 September 2009, in final form 4 November 2009
Published 30 November 2009
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