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Measurement and modeling of ErAs:In0.53Ga0.47As nanocomposite photoconductivity for THz generation at 1.55 µm pump wavelength

Suen, J. Y. and Krogen, P. R. and Preu, Sascha and Lu, Hong and Gossard, Arthur C. and Driscoll, D. C. and Lubin, P. M. (2014):
Measurement and modeling of ErAs:In0.53Ga0.47As nanocomposite photoconductivity for THz generation at 1.55 µm pump wavelength.
In: Journal of Applied Physics, pp. 013703, 116, [Online-Edition: http://dx.doi.org/10.1063/1.4886180],
[Article]

Abstract

We present new high-resolution measurements of transient time-domain photoconductivity in ErAs:InGaAs superlattice nanocomposites intended for THz photoconductive switches and photomixers using a pure optical pump-probe method. We developed a model, using separate photocarrier trapping, recombination, and thermal reactivation processes, which very accurately fits the measurements. The measured material structures all exhibit a slow secondary decay process, which is attributed to thermal reactivation of the trapped carriers, either into the conduction band, or into high-energy defect states. We examined the influence of superlattice structure, dopants, DC bias, and temperature. Analysis shows that all of the THz energy produced by the photocarrier trapping and decay processes are at frequencies less than 1 THz, while the reactivation process only serves to create a large portion of the bias power dissipated. Energy higher than 1 THz must be created by a fast generation process or band-filling saturation. This allows pulsed THz generation even from a long-lifetime material. Pure optical pump-probe measurements are necessary to expose slow material processes, and eliminate the influence of electrical terminals and THz antennas. These measurements and modeling of THz photoconductive devices are necessary in order to optimize the output spectrum and power.

Item Type: Article
Erschienen: 2014
Creators: Suen, J. Y. and Krogen, P. R. and Preu, Sascha and Lu, Hong and Gossard, Arthur C. and Driscoll, D. C. and Lubin, P. M.
Title: Measurement and modeling of ErAs:In0.53Ga0.47As nanocomposite photoconductivity for THz generation at 1.55 µm pump wavelength
Language: English
Abstract:

We present new high-resolution measurements of transient time-domain photoconductivity in ErAs:InGaAs superlattice nanocomposites intended for THz photoconductive switches and photomixers using a pure optical pump-probe method. We developed a model, using separate photocarrier trapping, recombination, and thermal reactivation processes, which very accurately fits the measurements. The measured material structures all exhibit a slow secondary decay process, which is attributed to thermal reactivation of the trapped carriers, either into the conduction band, or into high-energy defect states. We examined the influence of superlattice structure, dopants, DC bias, and temperature. Analysis shows that all of the THz energy produced by the photocarrier trapping and decay processes are at frequencies less than 1 THz, while the reactivation process only serves to create a large portion of the bias power dissipated. Energy higher than 1 THz must be created by a fast generation process or band-filling saturation. This allows pulsed THz generation even from a long-lifetime material. Pure optical pump-probe measurements are necessary to expose slow material processes, and eliminate the influence of electrical terminals and THz antennas. These measurements and modeling of THz photoconductive devices are necessary in order to optimize the output spectrum and power.

Journal or Publication Title: Journal of Applied Physics
Volume: 116
Divisions: 18 Department of Electrical Engineering and Information Technology > Institute for Microwave Engineering and Photonics > Terahertz Systems Technology
18 Department of Electrical Engineering and Information Technology
18 Department of Electrical Engineering and Information Technology > Institute for Microwave Engineering and Photonics
Date Deposited: 19 Jun 2015 11:21
Official URL: http://dx.doi.org/10.1063/1.4886180
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