Terahertz radiation from MBE-grown p-InAs on GaAs/GaSb excited by 800-nm and 1.55 µm femtosecond lasers
InAs (p-doped) is grown on a GaAs-buffered GaSb substrate via molecular beam epitaxy. The heterostructure is tested as an emitter in a terahertz time-domain spectroscopy system with a 1550-nm-wavelength femtosecond laser. We achieve an enhancement in the terahertz radiation intensity of approximately twice compared to that of bulk p-InAs. Pump power dependence of the THz signal (800-nm femtosecond laser excitation) show similar trend in the saturation fluence of the samples. Azimuthal-angle measurements reveal surge current mechanism via photo-Dember effect.