Abstract-Fast room temperature detection of terahertz quantum cascade lasers with graphene loaded bow-tie plasmonic antenna arrays

Riccardo Degl'Innocenti, Long Xiao, David S. Jessop, Stephen J Kindness, Yuan Ren, Hungyen Lin, J. Axel Zeitler, Jack A. Alexander-Webber, Hannah J Joyce, Philipp Braeuninger-Weimer, Stephan Hofmann, Harvey E Beere, and David A. Ritchie

ACS Photonics, Just Accepted Manuscript

DOI: 10.1021/acsphotonics.6b00405

Publication Date (Web): September 20, 2016

Copyright © 2016 American Chemical Society

https://www.blogger.com/blogger.g?blogID=124073320791841682#editor/target=post;postID=4022381804460754923

We present a fast room temperature terahertz detector based on interdigitated bow-tie antennas contacting graphene. Highly efficient photodetection was achieved by using two metals with different work functions as the arms of a bow-tie antenna contacting graphene. Arrays of the bow-ties were fabricated in order to enhance the responsivity and coupling of the incoming light to the detector realizing an efficient imaging system. The device has been characterized and tested with a terahertz quantum cascade laser emitting in single frequency around 2 THz yielding a responsivity of ~ 34 μA/W and a noise-equivalent-power of ~1.5E-7W/Hz1/2

Abstract-Increased Photoconductivity Lifetime in GaAs Nanowires by Controlled n-Type and p-Type Doping

Jessica L Boland, Alberto Casadei, Gozde Tutuncuoglu, Federico Matteini, Christopher L Davies, Fauzia Jabeen,Hannah J Joyce, Laura M. Herz, Anna Fontcuberta i Morral, and Michael B Johnston

ACS Nano, Just Accepted Manuscript

DOI: 10.1021/acsnano.5b07579

Publication Date (Web): March 9, 2016

Copyright © 2016 American Chemical Society

http://pubs.acs.org/doi/abs/10.1021/acsnano.5b07579?journalCode=ancac3

Controlled doping of GaAs nanowires is crucial for the development of nanowire-based electronic and optoelectronic devices. Here, we present a non-contact method based on time resolved terahertz photoconductivity for assessing n and p type doping efficiency in nanowires. Using this technique, we measure extrinsic electron and hole concentrations in excess of 1018cm-3 for GaAs nanowires with n-type and p-type doped shells. Furthermore, we show that controlled doping can significantly increase the photoconductivity lifetime of GaAs nanowires by over an order of magnitude: from 0.13ns in undoped nanowires to 3.8ns and 2.5ns in n-doped and p-doped nanowires respectively. Thus, controlled doping can be used to reduce the effects of parasitic surface recombination in optoelectronic nanowire devices, which is promising for nanowire devices such as solar cells and nanowire lasers.

Abstract-Single Nanowire Photoconductive Terahertz Detectors

Kun Peng , Patrick Parkinson , Lan Fu , Qiang Gao , Nian Jiang , Yanan Guo , Fan Wang , Hannah J Joyce , Jessica L Boland , Hark Hoe Tan , Chennupati Jagadish , and Michael B Johnston

Nano Lett., Just Accepted Manuscript

DOI: 10.1021/nl5033843

Publication Date (Web): December 9, 2014

Copyright © 2014 American Chemical Society

http://pubs.acs.org/doi/abs/10.1021/nl5033843

Spectroscopy and imaging in the terahertz (THz) region of the electromagnetic spectrum has proven to provide important insights in fields as diverse as chemical analysis, materials characterization, security screening and non-destructive testing. However, compact optoelectronics suited to the most powerful terahertz technique – time-domain spectroscopy – are lacking. Here, we implement single GaAs nanowires as microscopic coherent THz sensors and for the first time incorporated them into the pulsed time-domain technique. We also demonstrate the functionality of the single nanowire THz detector as a spectrometer by using it to measure the transmission spectrum of a 290 GHz low pass filter. Thus nanowires are shown to be well suited for THz device applications, and hold particular promise as near-field terahertz sensors.