Nanoscale Devices for Rectification of High Frequency Radiation from the Infrared through the Visible: A New Approach

Abstract

We present a new and viable method for optical rectification. This approach has been demonstrated both theoretically and experimentally and is the basis fot the development of devices to rectify radiation through the visible. This technique for rectification is based not on conventional material or temperature asymmetry as used in MIM (metal/insulator/metal) or Schottky diodes, but on a purely sharp geometric property of the antenna. This sharp “tip” or edge with a collector anode constitutes a tunnel junction. In these devices the rectenna (consisting of the antenna and the tunnel junction) acts as the absorber of the incident radiation and the rectifier. Using current nanofabrication techniques and the selective atomic layer deposition (ALD) process, junctions of 1 nm can be fabricated, which allow for rectification of frequencies up to the blue portion of the spectrum. To assess the viability of our approach, we review the development of nanoantenna structures and tunnel junctions capable of operating in the visible region. In addition, we review the detailed process of rectification and present methodologies for analysis of diode data. Finally, we present operational designs for an optical rectenna and its fabrication and discuss outstanding problems and future work.

The rectenna device: From theory to practice (a review)

“…Rectification in these devices is due to variation in tunnelling rates caused by barrier asymmetry due to material selection, device geometry, thermal asymmetry, and photon induced deviation in electron flux distribution across occupied and unoccupied states 105 , all contributing towards a nonlinear asymmetric I-V response. In the current review, we will qualitatively explain the nature of the I-V asymmetry taking into account the material selection for planar MIM devices under no illumination and thermal equilibrium.…”

“…Under illumination, electron tunnelling is stimulated by different processes depending whether an antenna is or is not coupled to the diode. Further reading is suggested in [105,165,166,169]. Thermionic emission also contributes to tunnel diodes' I-V curves 165,188,189 , especially to devices with thick insulating layers 188 .…”

“…However when the common lithographic techniques are supplemented by a recently optimised selective area atomic layer deposition technology 197 , tunnel junctions of approximately 1 nm can be produced. This enables designs of antenna-rectifier coupled devices other than the more common planar types, which have great potential for success (see Miskovsky et al [105]). Another challenge is fabricating arrays of nano-scaled lateral diodes to be of the same size scale as required for high frequency antennas.…”

“…Finally, Figure 31 shows schematics of the approach proposed by Miskovsky et al 105 . This design consists of an array of needle-like nanostructures, which have been designed to utilise a geometric constraint for the tunnel-ing mechanism.…”

“…We aim to expand upon a few short reviews, [3][4][5]9,100,105], that have been published, bringing the reader up to date with a more detailed overview of the device. This article will be the first to bring together all relevant research not only on the rectenna as a whole device, but also the research on its two main components -the antenna and the rectifier.…”