4 October 2005 Photodetector based on networks of carbon nanotubes on decomposed SOI
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Proceedings Volume 5971, Photonic Applications in Nonlinear Optics, Nanophotonics, and Microwave Photonics; 597118 (2005); doi: 10.1117/12.625485
Event: Photonics North, 2005, Toronto, Canada
Abstract
We report a novel method of fabricating self-assembled carbon nanotube (CNT) on Si nanocrystals and the photocurrent from this network. Silicon-on-insulator (SOI) substrate with 10nm thin top silicon layer is annealed at elevate temperature in an ultra-high vacuum environment. The Si layer dewets and aggregates into Si nanocrystal islands with dimensions about 90 nm high, 100-150 nm wide, and 200nm apart. 1nm thin Fe film is deposited on the decomposed SOI as catalyst for CNT growth. The growth is done by chemical vapor deposition (CVD) at 900 °C with a flow of CH4 at 400sccm and H2 at 20sccm. The CVD grown CNTs show strong preferential growth on the top portion of the Si nanocrystals and form a suspended network connecting the nanocrystals. No photolithographic process is needed to create this self-assembled CNT network. We find that the reason that few CNT are found on the oxide surface is because of the influence of the island topography on the CH4 gas flow pattern, with feedstock unable to reach the oxide surface when the islands are close to each other. We demonstrate that, by shining a low power 650nm wavelength commercial red laser pointer on this network, it generates photocurrent on the level of 20nA photocurrent under 1 volt bias condition. Since a 100 mW 1.175 μm wavelength IR laser does not generate any distinguishable photocurrent in our measurement setup, we believe the photocurrent generated by 650 nm red laser mainly comes from the Si nanocrystals instead of the CNTs. We demonstrate that a dense, self-assembled CNT network can be formed on the decomposed Si nanocrystals and can be used as conducting media for electric measurement.
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Hao-Chih Yuan, Bin Yang, Jason M. Simmons, Matthew S. Marcus, Zhenqiang Ma, Mark A. Eriksson, Max G. Lagally, "Photodetector based on networks of carbon nanotubes on decomposed SOI", Proc. SPIE 5971, Photonic Applications in Nonlinear Optics, Nanophotonics, and Microwave Photonics, 597118 (4 October 2005); doi: 10.1117/12.625485; https://doi.org/10.1117/12.625485
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KEYWORDS
Silicon

Nanocrystals

Electrodes

Oxides

Chemical vapor deposition

Semiconductors

Carbon nanotubes

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