Selective area growth of III-V semiconductor compounds using molecular beam epitaxy (MBE) has been envisaged as an <I>in situ</I> fabrication method for integrated circuits on a nanometer scale. However, conventional selective area growth techniques using MBE are limited to only two dimensional, template-like, pattering of the epilayer. The work presented in this dissertation describes the selective area growth of AlGaAs based structures using a Ga<SUP>+</SUP> focused ion beam (FIB) as one of the group III matrix element sources in a MBE growth chamber. Since stoichiometric epitaxy of a III-V semiconductor compound can be achieved with an excess supply of the group V element, supplying the Ga matrix element as a FIB, under standard MBE growth conditions, was shown to facilitate a maskless, <I>in situ,</I> lateral selective area growth technique for GaAs. Consequently, this FIB-MBE growth technique, FIMBE, has the potential of exploiting the precise control over the elemental composition afforded by MBE in the growth (<I>z</I>) direction with the high spatial resolution of FIB technology in the lateral (<I>xy</I>) plane. Moreover, it offers the unique facility of growing fully integrated three-dimensional structures into one as-grown epilayer structure. The necessary modifications required to a standard FIB column and MBE growth chamber to fully exploit the combination of these two technologies, along with the operational performance of the fully integrated FIMBE growth system are presented. A study of the effect of incident ion energy (E<SUB>ion</SUB>) on the film growth rate identified two growth rate limiting processes; (i) the inherent properties of the Ga<SUP>+</SUP> FIB (E<SUB>ion</SUB> <25eV) and (ii) material sputtering from the growing GaAs film (E<SUB>ion</SUB>>100eV). However, a systematic reduction in the surface roughness of the FIMBE grown GaAs films was observed with increasing incident ion energy.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:596523 |
| Date | January 2001 |
| Creators | Beere, H. E. |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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