Free-space terahertz radiation from a LT-GaAs-on-quartz large-area photoconductive emitter

We report on large-area photoconductive terahertz (THz) emitters with a low-temperature-grown GaAs (LT-GaAs) active layer fabricated on quartz substrates using a lift-off transfer process. These devices are compared to the same LT-GaAs emitters when fabricated on the growth substrate. We find that t...

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Bibliographic Details
Published in:Optics express 2016-11, Vol.24 (23), p.26986-26997
Main Authors: Bacon, David R, Burnett, Andrew D, Swithenbank, Matthew, Russell, Christopher, Li, Lianhe, Wood, Christopher D, Cunningham, John, Linfield, Edmund H, Davies, A Giles, Dean, Paul, Freeman, Joshua R
Format: Article
Language:English
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Summary:We report on large-area photoconductive terahertz (THz) emitters with a low-temperature-grown GaAs (LT-GaAs) active layer fabricated on quartz substrates using a lift-off transfer process. These devices are compared to the same LT-GaAs emitters when fabricated on the growth substrate. We find that the transferred devices show higher optical-to-THz conversion efficiencies and significantly larger breakdown fields, which we attribute to reduced parasitic current in the substrate. Through these improvements, we demonstrate a factor of ~8 increase in emitted THz field strength at the maximum operating voltage. In addition we find improved performance when these devices are used for photoconductive detection, which we explain through a combination of reduced parasitic substrate currents and reduced space-charge build-up in the device.
ISSN:1094-4087
1094-4087
DOI:10.1364/oe.24.026986