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Title: Electronic transport in indium arsenide nanowires grown on silicon
Author: Sourribes, M. J. L.
ISNI:       0000 0004 5357 8439
Awarding Body: University College London (University of London)
Current Institution: University College London (University of London)
Date of Award: 2014
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Indium arsenide (InAs) nanowires are attracting a growing interest in the semiconductor industry as their remarkable properties make them ideal candidates for future applications in a wide variety of electronic, photonic and sensing devices. In the present work, InAs nanowires are grown via solid-source molecular beam epitaxy on Si (111) substrates without the use of heterocatalytic nanoparticle seeds. The native oxide layer forming easily on InAs nanowires must be removed prior to metallisation to achieve highly transparent contacts. We present a systematic comparative study of the contact resistance between InAs nanowires and metals following the use of (a) a wet etching in an ammonium polysulfide solution or (b) an argon milling process. Nanowires treated by the argon milling process with in situ deposition of metallic contacts exhibit a contact resistance which is more than one order of magnitude lower than that of nanowires treated with ammonium polysulfide. From fourpoint measurements, an upper bound of 1.4×10−7 .cm2 is extracted for the contact resistivity of metallic contacts on nanowires treated by the argon milling process. While the growth of semiconductor nanowires on silicon allows their direct integration with the established CMOS technology, the absence of a heterocatalyst usually results in a pronounced polytypism in the nanowires, proved to be detrimental to their optical and electrical properties. To solve this issue, InAs1−xSbx nanowires (0 _ x _ 0.15) were grown on silicon substrate via a catalyst-free MBE process. We observed a sharp decrease of stacking fault density in the InAs1−xSbx nanowire crystal structure with increasing antimony content. InAs0.85Sb0.15 nanowires exhibit a mobility three times larger than InAs nanowires. Finally both magnetic-field-dependent and gate-voltage-dependent measurements of universal conductance fluctuations and of localisation effects were performed on InAs and InAs1−xSbx nanowires at low temperature. From the analysis of the fluctuation amplitude and the correlation field, a phase-coherence length in the hundred nanometre range is observed for all nanowires below 10 K.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available