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Low temperature grown photoconductive antennas for pulsed 1060 nm excitation: Influence of excess energy on the electron relaxation

: Dietz, Roman; Brahm, Anika; Velauthapillai, Ajanth; Wilms, Annika; Lammers, Christian; Globisch, Bernd; Koch, Martin; Notni, Gunther; Tünnermann, Andreas; Göbel, Thorsten; Schell, Martin


Journal of infrared, millimeter, and terahertz waves 36 (2015), No.1, pp.60-71
ISSN: 1866-6892
ISSN: 1866-6906
Journal Article
Fraunhofer IOF ()
Fraunhofer HHI ()
photoconductor; low temperature growth; Terahertz Time Domain Spectroscopy; Transient White Light Spectroscopy

We investigate properties of MBE grown photoconductive terahertz (THz) antennas based on the InGaAs/InAlAs/InP material system aimed for an excitation wavelength of approx. 1060 nm. Therefore, we analyze several different approaches concerning growth parameters, layer and material compositions as well as doping. The carrier dynamics are probed via transient white-light pump-probe spectroscopy as well as THz Time Domain Spectroscopy (TDS) measurements. We find that the electron capture probability is reduced for higher electron energies. By adjusting the material band gap this can be resolved and lifetimes of 1.3 ps are obtained. These short lifetimes enable the detection of THz TDS spectra with a bandwidth exceeding 4 THz.