Direct and quantitative absorptive spectroscopy of nanowires

Photonic nanostructures exhibit unique optical properties that are attractive in many different applications. However, measuring the optical properties of individual nanostructures, in particular the absorptive properties, remains a significant challenge. Conventional methods typically provide either an indirect or qualitative measure of absorption. The objective of this thesis is to therefore demonstrate a method capable of directly and quantitatively measuring the absorptive properties of individual nanostructures. This method is based on atomic force microscope (AFM) cantilever thermometry where a bimorph cantilever is used as a heat flux sensor. These sensors operate on the principle of a thermomechanical bending response and by virtue of their dimensionality, are capable of picowatt sensitivity. To validate the use of this technique, a single silicon nanowire is measured. By attaching a silicon nanowire to a cantilever and illuminating the sample with monochromatic light, the absolute absorptance spectrum of the nanowire was measured and shown to match well with theory. This spectroscopic technique can conceivably be used to measure even smaller samples, samples which cannot be characterized using conventional methods.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2012

Author dc:creator

• Tong, Jonathan Kien-Kwok

Advisor dc:contributor.advisor

• Gang Chen.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/78197

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/78197