1.55 μm ultrafast photoconductive switches based on ErAs:InGaAs

The electron capture time in superlattice structures consisting of periodically spaced layers of self-assembled ErAs nanoislands and In(0.53)Ga(0.47)As is investigated on photoconductive switches as a function of the superlattice period using photocurrent autocorrelation and pulsed laser excitation at 1.55 mu m. The capture time can be tuned from picoseconds all the way down to 0.2 ps by changing the periodicity. Two different Be doping schemes are explored to reduce the dark current. The resulting characteristics indicate that ErAs:InGaAs may serve as a high performance photoconductive material at this wavelength for pulsed terahertz emission and detection. (C) 2008 American Institute of Physics.