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Proceedings Paper

Characterization and physics of top-down silicon nanowire phototransistors
Author(s): Arthur Zhang; James Cheng; Hongkwon Kim; Yisi Liu; Yu-Hwa Lo
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Paper Abstract

Nanowire photodetectors of a variety of materials have been attracting increased attention due to their potential for very high sensitivity detection. Silicon photodetectors are of particular interest for detection in the visible spectrum, having many benefits including cost of substrate, ease of processing, and ability for integration with conventional fabrication techniques. Using top-down fabrication techniques results in additional benefits of precise control of number, geometry, and placement of these wires. To demonstrate the potential of these devices, top-down, vertical silicon nanowire phototransistor arrays have been fabricated using ebeam lithography and deep reactive ion and inductively coupled plasma etching. These devices show a much higher phototransistive gain over nanowire photodiodes with similar geometry under illumination from a 635nm laser. Low temperature measurements also show the dependence of dark current and sensitivity on temperature. The mechanism responsible for this gain is shown to be dominated by the large surface-to-volume ratio of nanowires where charge capture and recombination at the surface creates a radial gate bias which is modulated with light intensity. 3D numerical simulations validate this mechanism and further show the dependence of device behavior on nanowire doping, geometry, and surface state density. This will allow for the precise engineering of these devices to achieve the maximum sensitivity obtainable as we strive for the ultimate goal of single photon resolution.

Paper Details

Date Published: 23 January 2010
PDF: 8 pages
Proc. SPIE 7608, Quantum Sensing and Nanophotonic Devices VII, 76081D (23 January 2010); doi: 10.1117/12.841201
Show Author Affiliations
Arthur Zhang, Univ. of California, San Diego (United States)
James Cheng, Univ. of California, San Diego (United States)
Hongkwon Kim, Univ. of California, San Diego (United States)
Yisi Liu, Agiltron, Inc. (United States)
Yu-Hwa Lo, Univ. of California, San Diego (United States)


Published in SPIE Proceedings Vol. 7608:
Quantum Sensing and Nanophotonic Devices VII
Manijeh Razeghi; Rengarajan Sudharsanan; Gail J. Brown, Editor(s)

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