1550 nm Compatible Ultrafast Photoconductive Material Based on a GaAs/ErAs/GaAs Heterostructure

摘要

The sub-bandgap absorption and ultrafast relaxation in a GaAs/ErAs/GaAs heterostructure are reported. The infrared absorption and 1550 nm-excited ultrafast photo-response are studied by Fourier transform infrared spectrometry and time-domain pump-probe technique. The two absorption peaks located at 2.0 (0.62 eV) and 2.7 mu m (0.45 eV) are originated from the ErAs/GaAs interfacial Schottky states and the ErAs itself, respectively. The photo-excited carrier lifetime, excited using 1550 nm light, is measured to be as low as 190 fs for the GaAs/ErAs/GaAs heterostructure, making it a promising material for 1550-nm-technology-compatible, high critical-breakdown-field THz devices. The relaxation mechanism is proposed and the functionality of ErAs is revealed.