Abstract-Three-dimensional cross-nanowire networks recover full terahertz state

Kun Peng, Dimitars Jevtics, Fanlu Zhang, Sabrina Sterzl, Djamshid A. Damry, Mathias U. Rothmann, Benoit Guilhabert, Michael J. Strain, Hark H. Tan, Laura M. Herz, Lan Fu, Martin D. Dawson, Antonio Hurtado, Chennupati Jagadish, Michael B. Johnston,

https://science.sciencemag.org/content/368/6490/510.abstract

Nanowire-based THz detection

Terahertz (THz) radiation is an interesting region of the electromagnetic spectrum lying between microwaves and infrared. Non-ionizing and transparent to most fabrics, it is finding application in security screening and imaging but is also being developed for communication and chemical sensing. To date, most THz detectors have focused just on signal intensity, an effort that discards half the signal in terms of the full optical state, including polarization. Peng et al. developed a THz detector based on crossed nanowires (arranged in a hash structure) that is capable of resolving the full state of the THz light. The approach provides a nanophotonic platform for the further development of THz-based technologies.

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.