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Proceedings Paper

Seeing the unseen with localized optical contrast
Author(s): Swathi Suran; Krishna Bharadwaj; Srinivasan Raghavan; Manoj M. Varma
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Paper Abstract

Optical wide-field imaging of sub-diffraction limit nanostructures is of interest in a wide array of applications. In applications where the nanostructures to be visualized are well isolated, a high enough optical contrast is sufficient to detect these. Here we demonstrate a technique to visualize nanoscale features, such as grain boundaries in Chemical Vapor Deposited (CVD) single layer graphene, which are just a few atom length defects, using regular bright field optical microscopy. This remarkably low lateral length scale was imaged using of a special thin film structure consisting of a water-soluble thin film layer deposited on a metal substrate, which produces a strong color change as a function of the film thickness. Small local water transport differences in the graphene layer result in thickness variation of the underlying thin film due to its solubility in water and produces color contrast readily observable under a normal brightfield optical microscope with the naked eye. We demonstrate the use of this technique for direct optical visualization of grain boundaries in graphene as wide as 2-5 nm and sub-100 nm photoresist lines. By using super-resolution image processing algorithms, we may be able to detect structure even smaller in size than currently achieved. We believe that this technique can be extended to single molecule detection.

Paper Details

Date Published: 22 April 2016
PDF: 6 pages
Proc. SPIE 9721, Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications XIII, 97210U (22 April 2016); doi: 10.1117/12.2212028
Show Author Affiliations
Swathi Suran, Indian Institute of Science (India)
Krishna Bharadwaj, Indian Institute of Science (India)
Srinivasan Raghavan, Indian Institute of Science (India)
Manoj M. Varma, Indian Institute of Science (India)

Published in SPIE Proceedings Vol. 9721:
Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications XIII
Alexander N. Cartwright; Dan V. Nicolau; Dror Fixler, Editor(s)

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