Share Email Print

Proceedings Paper

Broadband enhanced graphene photodetector with fractal metasurface (Conference Presentation)

Paper Abstract

Graphene has been demonstrated to be a promising photo-detection material because of its ultra-broadband absorption, compatibility with CMOS technology, and dynamic tunability. There are multiple known photo-detection mechanisms in graphene, among which the photovoltaic effect has the fastest response time thus is the prioritized candidate for ultrafast photodetector. There have been numerous efforts to enhance the intrinsically low sensitivity in graphene photovoltaic detectors using metallic plasmonic structures, but such plasmonic enhancements are mostly narrowband and polarization dependent. In this work, we propose a gold Cayley-tree fractal metasurface design that has a multi-band resonance, to realize broadband and polarization-insensitive plasmonic enhancement in graphene photovoltaic detectors. When illuminated with visible light, the fractal metasurface exhibits multiple hotspots at the metal-graphene interface, where the electric field of the incident electromagnetic wave is enhanced and contributes to generating excess electron-hole pairs in graphene. The large metal-graphene interface length in the fractal metasurface also helps to harvest at a higher efficiency the electron-hole pairs by built-in electric field due to metal-graphene potential gradient. To demonstrate the concept, we carried out experiment using Ar-Kr CW laser, an optical chopper, and lock-in amplifier. We obtained experimentally an almost constant ten-fold enhancement of photocurrent generated on the fractal metasurface compared to that generated on the plain gold-graphene edge, at all tested wavelengths (488 nm, 514 nm, 568 nm, and 647 nm). We also observed an unchanged photoresponse with respect to incident light polarization angles, which is a result of the highly symmetric geometry of the fractal metasurface.

Paper Details

Date Published: 9 November 2016
PDF: 1 pages
Proc. SPIE 9918, Metamaterials, Metadevices, and Metasystems 2016, 99181S (9 November 2016); doi: 10.1117/12.2237050
Show Author Affiliations
Di Wang, Purdue Univ. (United States)
Jieran Fang, Purdue Univ. (United States)
Clayton T. DeVault, Purdue Univ. (United States)
Ting-Fung Chung, Purdue Univ. (United States)
Yong P. Chen, Purdue Univ. (United States)
Alexandra Boltasseva, Purdue Univ. (United States)
DTU Fotonik (Denmark)
Technical Univ. of Denmark (Denmark)
Vladimir M. Shalaev, Purdue Univ. (United States)
Alexander V. Kildishev, Purdue Univ. (United States)

Published in SPIE Proceedings Vol. 9918:
Metamaterials, Metadevices, and Metasystems 2016
Nader Engheta; Mikhail A. Noginov; Nikolay I. Zheludev, Editor(s)

© SPIE. Terms of Use
Back to Top
Sign in to read the full article
Create a free SPIE account to get access to
premium articles and original research
Forgot your username?