Strain-Induced InGaAs-Based Photoconductive Terahertz Antenna Detector
D. V. Lavrukhin, A. E. Yachmenev, Yurii G. Goncharov, Kirill I. Zaytsev, Р. А. Хабибуллин, A. M. Buryakov, Е. Д. Мишина, Д. С. Пономарев
Abstract
We report on a terahertz (THz) detector based on a photoconductive antenna (PCA) utilizing an artificially strained undoped InGaAs/InAlAs superlattice (SL). Using our laboratory pulsed THz time-domain spectrometer, we demonstrate the advancement of the strain-induced SL-based PCA detector (SID) when operating with an optical probe power of P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">opt</sub> > 6 mW over the PCA detector based on a lattice-matched InGaAs/InAlAs SL (LMD). Both detectors demonstrate a broad frequency bandwidth of 3.5 THz at the excitation wavelength of 780 nm with a signal-to-noise ratio (SNR) of ~ 70 dB. The experimental results demonstrate a change in the behavior of two detectors: At P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">opt</sub> = 1 mW, the LMD shows a bit increased SNR compared to that for SID, while vice versa at P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">opt</sub> = 10 mW. Also, SID shows a quadratic dependence of its SNR on P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">opt</sub> while the SNR for LMD starts saturating at P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">opt</sub> ~ 5 mW. Moreover, the noise floor in SID is almost independent on probe power, while the noise floor for LMD demonstrates a rapid growth with an increase of P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">opt</sub> . We believe that SID coupled to a fiber telecommunication wavelength laser could open a pathway toward the development and fabrication of portable and cost-effective THz photoconductive devices.