Long Wavelength Low Temperature Grown GaAs and InP-Based Terahertz Photoconductors Devices

A series of molecular beam epitaxy low temperature grown structures with various epitaxial and doping profiles are studied, and photoconductive antennas made on these structures are evaluated in a time-domain spectroscopy system. The structures are synthesized to absorb light at wavelengths of 800 nm, and 1 and 1.55 μm. Apertures and dipoles are designed as photoconductive antennas. The key findings for the long wavelength devices (1.55 μm) demonstrate materials with very short carrier lifetimes ( <; 1 ps), high resistivity ( >; 10⁶ Ω/sq) , and system responses with THz pulses having power-to-noise ratio of 50 dB or more. These characteristics are among the best ever reported for such material systems, making them efficient THz emitters and detectors for various optoelectronic applications, especially for telecom laser-driven continuous wave THz systems.