Content area
Full Text
LETTERS
PUBLISHED ONLINE: 28 SEPTEMBER 2015 | http://dx.doi.org/10.1038/nnano.2015.216
Web End =DOI: 10.1038/NNANO.2015.216
Infrared rectication in a nanoantenna-coupled metal-oxide-semiconductor tunnel diode
Paul S. Davids*, Robert L. Jarecki, Andrew Starbuck, D. Bruce Burckel, Emil A. Kadlec, Troy Ribaudo, Eric A. Shaner and David W. Peters
Direct rectication of electromagnetic radiation is a well-established method for wireless power conversion in the microwave region of the spectrum, for which conversion efciencies in excess of 84% have been demonstrated16. Scaling to the infrared or optical part of the spectrum requires ultrafast recti-cation710 that can only be obtained by direct tunnelling11,12. Many research groups have looked to plasmonics to overcome antenna-scaling limits and to increase the connement10,1321.
Recently, surface plasmons on heavily doped Si surfaces were investigated as a way of extending surface-mode connement to the thermal infrared region22. Here we combine a nanostructured metallic surface with a heavily doped Si infrared-reective ground plane designed to conne infrared radiation in an active electronic direct-conversion device. The interplay of strong infrared photonphonon coupling and electromagnetic connement in nanoscale devices is demonstrated to have a large impact on ultrafast electronic tunnelling in metaloxide semiconductor (MOS) structures. Infrared dispersion of SiO2 near a longitudinal optical (LO) phonon mode gives large trans-verse-eld connement in a nanometre-scale oxide-tunnel gap as the wavelength-dependent permittivity changes from 1 to 0, which leads to enhanced electromagnetic elds at material interfaces and a rectied displacement current that provides a direct conversion of infrared radiation into electric current. The spectral and electrical signatures of the nanoantenna-coupled tunnel diodes are examined under broadband black-body and quantum-cascade laser (QCL) illumination. In the region near the LO phonon resonance, we obtained a measured photoresponsivity of 2.7 mA W1 cm2 at 0.1 V.
We present a new device concept for the direct rectication of infrared radiation from thermal sources that pairs a large-area nanoantenna with an integrated MOS tunnel diode, as shown schematically in Fig. 1a. The integrated nanoantenna rectier consists of a periodic Al grating, a thin gate-oxide layer and a heavily n-type-doped Si on an n-type epitaxial (epi) substrate that acts both as an infrared ground plane and an electrical contact. A thin, high-quality gate oxide is grown directly on the heavily doped layer. The oxide thickness is chosen to be 35 nm...