Terahertz-frequency photoconductive detectors fabricated from metal-organic chemical vapor deposition-grown Fe-doped InGaAs

We report the detection of terahertz frequency radiation using photoconductive antennas fabricated from Fe-doped InGaAs, grown by metal-organic chemical vapor deposition. Coherent photoconductive detection is demonstrated using femtosecond laser pulses centered at either an 800 or a 1550 nm wavelength. The InGaAs resistivity and the sensitivity of photoconductive detection are both found to depend on the Fe-doping level. We investigate a wide range of probe laser powers, finding a peak in detected signal for similar to 5 mW probe power, followed by a reduction at larger powers, attributed to screening of the detected THz field by photo-generated carriers in the material. The measured signal from Fe: InGaAs photoconductive detectors excited at 800 nm is four times greater than that from a low-temperature-grown GaAs photodetector with identical antenna design, despite the use of a ten times smaller probe power. (C) 2011 American Institute of Physics. [doi:10.1063/1.3571289]