GaBiAs: A material for optoelectronic terahertz devices

GaBiAs layers have been grown by molecular beam epitaxy at low $(270–330°C)$ temperatures and were characterized by several experimental techniques. It was shown that the spectral photosensitivity cutoff wavelength reaches $∼1.4μm$ when the growth temperature is as low as $280°C$⁠. Optical pump–terahertz probe measurements made on these layers have evidenced that the electron trapping time decreases with decreasing growth temperature from 20 to about $1ps$⁠. GaBiAs layers were used for manufacturing photoconductive terahertz emitters and detectors, which, when excited with Ti:sapphire laser pulses, have demonstrated a signal bandwidth of $3THz$⁠.