title: Free-space terahertz radiation from a LT-GaAs-on-quartz large-area photoconductive emitter.
abstract: 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.
authors.forename: David R
authors.initials: DR
authors.lastname: Bacon
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Burnett
authors.forename: Matthew
authors.initials: M
authors.lastname: Swithenbank
authors.forename: Christopher
authors.initials: C
authors.lastname: Russell
authors.forename: Lianhe
authors.initials: L
authors.lastname: Li
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Wood
authors.forename: John
authors.initials: J
authors.lastname: Cunningham
authors.forename: Edmund H
authors.initials: EH
authors.lastname: Linfield
authors.forename: A Giles
authors.initials: AG
authors.lastname: Davies
authors.forename: Paul
authors.initials: P
authors.lastname: Dean
authors.forename: Joshua R
authors.initials: JR
authors.lastname: Freeman