Open AccessImpact of the contact metallization on the performance of photoconductive THz antennas
Author(s) -
Nico Vieweg,
M. Mikulics,
Maik Scheller,
K. Ezdi,
R. Wilk,
HeinzWilhelm Hübers,
Martín Koch
Publication year - 2008
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.16.019695
Subject(s) - ohmic contact , materials science , terahertz radiation , optoelectronics , femtosecond , laser , photoconductivity , diode , optics , layer (electronics) , equivalent series resistance , physics , nanotechnology , voltage , quantum mechanics
Both AuGe based alloys and Ti/Au metal layer stacks are widely used as ohmic metal contacts for photoconductive THz antennas made of low temperature grown GaAs. Here, we present the first systematic comparison between these two metallization types. A series of antennas of both kinds is excited by femtosecond laser pulses and by the emission from two diode lasers, i.e. we test the structures as pulsed THz emitters and as photomixers. In both cases, coherent and incoherent detection schemes are employed. We find that the power emitted from the antennas with AuGe metallization is 50% higher than that of antennas with a Ti/Au metal layer. From a comparison with a photomixer model we conclude that the higher output power results from a lower contact resistance of the AuGe contacts leading to an increased current flow. However, Ti/Au contacts have a higher thermal stability which might be advantageous if high system stability is called for.