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Title: Single electron conduction in 2-dimensional arrays of gold nanodots
Author: Ford, E. M.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2000
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This dissertation considers single electron conduction through arrays of nanometer-size metallic islands fabricated by Focused Ion Beam (FIB) lithography. Control of the array geometry and the corresponding electrical characteristics were achieved by variation of the FIB deposition conditions. Scanning electron microscopy was used to examine FIB depositions on Si/SiO2 substrates. For more accurate examination transmission electron microscopy was used to image arrays deposited on carbon membranes. Image analysis software revealed a general increase in island diameter and reduction of island density with increasing FIB dose. The average island size was found to decrease with increasing FIB landing energy, although the uniformity of the deposition was reduced. The process of island formation is discussed in relation to the trends observed. Devices were fabricated with a planar structure, consisting of closely-spaced (~10 nm) source and drain electrodes situated within a large area array of islands. The devices were created on silicon substrates with a top layer of thermally grown silicon dioxide. A chromium oxide film was deposited by R.F. sputtering and the electrodes were then defined by high-resolution electron beam lithography. Electrical measurements were carried out at temperatures between 4.2K and 300K. Characteristics typical of single-electron conduction were observed, including the Coulomb gap and staircase, and the reduction of the Coulomb gap width with increasing temperature. The width of the low-temperature Coulomb gap was found to diminish with increasing dose, while devices fabricated with higher landing energies have lower operating temperatures. A novel device structure was also fabricated, where a small number of gold islands were isolated on the surface of a silicon nanowire. Silicon wires of length ~1μm and width >10nm were fabricated reproducibly using a sacrificial metallic etch mask. The electrical characteristics exhibited Coulomb gaps consistent with single electron transport.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available