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An invisible metal–semiconductor photodetector


Nanotechnology has enabled the realization of hybrid devices and circuits in which nanoscale metal and semiconductor building blocks are woven together in a highly integrated fashion. In electronics, it is well known how the distinct material-dependent properties of metals and semiconductors can be combined to realize important functionalities, including transistors, memory and logic. We describe an optoelectronic device for which the geometrical properties of the constituent semiconductor and metallic nanostructures are tuned in conjunction with the materials properties to realize multiple functions in the same physical space. In particular, we demonstrate a photodetector in which the nanoscale electrical contacts have been designed to render the device ‘invisible’ over a broad frequency range. The structure belongs to a new class of devices that capitalize on the notion that nanostructures have a limited number of resonant, geometrically tunable optical modes whose hybridization and intermodal interference can be tailored in a myriad of useful ways.

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Figure 1: Design and operation of a hybrid gold/silicon nanowire photodetector.
Figure 2: Polarization-dependent light-scattering phenomena for a gold-covered silicon nanowire.
Figure 3: Comparison of the electric field distribution surrounding a bare and a cloaked nanowire on a gold substrate under TM incidence.
Figure 4: Spectral absorption properties of bare and gold-coated silicon nanowires.


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The authors acknowledge support from a Multidisciplinary University Research Initiative grant (Air Force Office of Scientific Research, grant no. FA9550-10-1-0264), the Air Force Office of Scientific Research (AFOSR; grant no. FA9550-08-1-0220) and the Interconnect Focus Center, one of six research centres funded under the Focus Center Research Program (FCRP), a Semiconductor Research Corporation entity. P.F. would also like to acknowledge support from Stanford Graduate Fellowship.

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P.F., N.E. and M.L.B. conceived the experiments. P.F. and U.K.C. performed numerical simulations. L.C. performed silicon nanowire growth. P.F. performed sample fabrication and carried out all measurements. F.A. assisted with photocurrent measurement. P.F. and M.L.B. wrote the first draft of the manuscript. All authors discussed the results and contributed to the final version of the manuscript.

Corresponding author

Correspondence to Mark L. Brongersma.

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The authors declare no competing financial interests.

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Fan, P., Chettiar, U., Cao, L. et al. An invisible metal–semiconductor photodetector. Nature Photon 6, 380–385 (2012).

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