Nanowires fabricated by Focused Ion Beam

Naik, Jay Prakash (2014). Nanowires fabricated by Focused Ion Beam. University of Birmingham. Ph.D.

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Abstract

This thesis reports research on nanowires fabricated by FIB lithography with experiments to understand their mechanical, electrical and hydrodynamic properties.

Au nanowires fabricated on Si\(_3\)N\(_4\) membranes with width below 50nm exhibit liquid like instabilities and below \(\sim\)20nm the instabilities grow destroying the nanowires due to the Rayleigh- Plateau instability. Stability is better in the case for Si substrates than for the insulators Si0\(_2\) and Si\(_3\)N\(_4\).

A series of 4-terminal resistance measurements were carried out on a "platinum" nanowire grown by FIB-induced decomposition of an organometallic precursor. Such nanowires are found to be a two phase percolating system, containing up to 70% by volume carbon. They have unexpected temperature behaviour which is explained using a percolation model with Kirkpatrick conduction in the presence of temperature induced strain.

Au nanowire bridges of very small diameter were probed using AFM to investigate their deformation and fracture strength. Below a diameter \(\sim\)50nm, the mechanical properties are consistent with liquid-like behaviour. After reaching the fracture, the gold molecules from the bridge retract towards the fixed ends; rebinding of the gold causing reforming of the nanowire bridge can occur.

FIB fabrication was also used to form a thermal bimorph MEMS cantilever which was investigated by AFM during actuation.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):