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Pulsed terahertz time domain spectroscopy of vertically structured photoconductive antennas

Faulks, R; Rihani, S; Beere, HE; Evans, MJ; Ritchie, DA; Pepper, M; (2010) Pulsed terahertz time domain spectroscopy of vertically structured photoconductive antennas. APPL PHYS LETT , 96 (8) , Article 081106. 10.1063/1.3313940.

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Abstract

We present a terahertz (THz) photoconductive emitter structure, which employs a n-doped layer underneath a low-temperature-grown GaAs region to enable the THz transient to couple vertically through a defined mesa. A nonlinear bias dependence is observed, yielding an order in magnitude improvement in power for a mesa device with a 100 mu m(2) area over a conventional planar control reference device at 32 V and 5 mW illumination power. We relate the bias dependence of the THz signal to the breakdown voltage observed in the current-voltage characteristic. Reducing the antenna gap size through reducing the thickness of the low temperature-GaAs region below 1 mu m shows a large improvement in the bandwidth of the device, with an enhancement of the normalized intensity between 0.2 to 2 THz for a bow-tie antenna geometry.

Type:Article
Title:Pulsed terahertz time domain spectroscopy of vertically structured photoconductive antennas
DOI:10.1063/1.3313940
Keywords:antennas, gallium arsenide, III-V semiconductors, photoconducting materials, semiconductor doping, TEMPERATURE-GROWN GAAS
UCL classification:UCL > School of BEAMS > Faculty of Engineering Science > Electronic and Electrical Engineering

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