Abstract-The Route to Nanoscale Terahertz Technology: Nanowire-based Terahertz Detectors and Terahertz Modulators

Jessica L Boland, Kun Peng, Sarwat Baig, Diamshid Damry, Patrick Parkinson, Lan Fu, Hark Hoe Tan,  

https://ieeexplore.ieee.org/document/8510319

In this work, we demonstrate novel THz detectors and modulators based on semiconductor nanowires. We show that single nanowire PC THz receivers exhibit excellent sensitivity, high SNR of 40, and a broad detection bandwidth up to 2 THz, comparable to the bulk InP PC receivers. We also demonstrate ultrafast THz modulation by GaAs nanowire polarisers with a less than 5ps switching time and a modulation depth of -8dB, We show an extinction of over 13% and dynamic range of -9dB, comparable to microsecond-switchable graphene- and metamaterial-based THz modulators.

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.