A novel antenna effect is demonstrated in arrays of 500, 200 and 100 silicon nanowires embedded in silicon dioxide. The gratings are analyzed using spectral and polarisation resolved photocurrent microscopy. Resonant enhancements in the electric field and photocurrent response are observed at multiple wavelengths corresponding to coupling of incident radiation into the grating's multiple-scattering electromagnetic modes. The photoresponse retains the sinusoidal polarisation anisotropy expected in single nanowires. The resonances are modeled using electromagnetic scattering theory and show excellent agreement with measurement. An experimental quality factor of Q=10 was measured for the gratings, exceeding that of a single wire, but lower than expected from theory. The difference is ascribed to the finite length of the wires and their termination at ohmic contacts. Strategies to improve Q are discussed, and a grating is presented to resonantly enhance light detection at red, green and blue wavelengths for application as a colour imaging sensor.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/42930 |
| Date | 28 November 2013 |
| Creators | Stewart, Corey |
| Contributors | Ruda, Harry E. |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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