Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/32495
Title: Fabrication and characterization of semiconductor nanowires for thermoelectric application
Authors: KWOK WAI KEUNG
Keywords: fabrication,characterization,semiconductor,nanowires,thermoelectric,VLS
Issue Date: 29-Jul-2011
Source: KWOK WAI KEUNG (2011-07-29). Fabrication and characterization of semiconductor nanowires for thermoelectric application. ScholarBank@NUS Repository.
Abstract: In this dissertation, the fabrication and characterization of germanium (Ge) and silicon (Si) nanowires are presented. Ge nanowires were grown using the vapour-liquid-solid (VLS) method while Si nanowires were fabricated by catalytic etching. The nanowires were then characterized in terms of their electrical resistivity and thermal conductivity. The 3? method was used to measure the thermal conductivity of the Ge nanowires. It was found that the thermal conductivity of the Ge nanowire was reduced by about 6 times as compared to bulk Ge. Catalytic etching using a metal catalyst was used to fabricate Si nanowires in this project. The mechanism of the catalytic etching fabrication technique is of interest since several details of the exact mechanism are still not clear. Different thicknesses of metals were investigated as a bi-layer blocking layer to test how these would affect the etching process. In order to understand better the catalytic etching mechanism, XPS and Auger SEM was used to find out if Si atoms diffused through the metal catalyst during the etching. It was found that there is no significant diffusion of Si from the underlying substrate through the metal catalyst during the catalytic etching process. It is therefore likely that catalytic etching of Si took place at the interface between the metal catalyst layer and the Si substrate, rather than at the interface between metal catalyst and the etchant solution as the latter would require Si atoms to diffuse from the underlying substrate through the metal catalyst to the metal-solution interface.
URI: http://scholarbank.nus.edu.sg/handle/10635/32495
Appears in Collections:Master's Theses (Open)

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