Afshin Jooshesh, Faezeh Fesharaki, Vahid Bahrami-Yekta, Mahsa Mahtab, Thomas Tiedje, Thomas E. Darcie, and Reuven Gordon
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-18-22140
Photocurrent generation in low-temperature-grown GaAs (LT-GaAs) has been significantly improved by growing a thin AlAs isolation layer between the LT-GaAs layer and semi-insulating (SI)-GaAs substrate. The AlAs layer allows greater arsenic incorporation into the LT-GaAs layer, prevents current diffusion into the GaAs substrate, and provides optical back-reflection that enhances below bandgap terahertz generation. Our plasmon-enhanced LT-GaAs/AlAs photoconductive antennas provide 4.5 THz bandwidth and 75 dB signal-to-noise ratio (SNR) under 50 mW of 1570 nm excitation, whereas the structure without the AlAs layer gives 3 THz bandwidth, 65 dB SNR for the same conditions.
© 2017 Optical Society of America
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