Comparison of continuous-wave terahertz wave generation and bias-field-dependent saturation in GaAs:O and LT-GaAs antennas

Abstract

Terahertz wave (THz) photoconductive (PC) antennas were fabricated on oxygen-implanted GaAs (GaAs:O) and low-temperature-grown GaAs (LT-GaAs). The measured cw THz power at 0.358 THz from the GaAs:O antenna is about twice that from the LT-GaAs antenna under the same testing conditions, with the former showing no saturation up to a bias of 40 kV/cm, while the latter is already beginning to saturate at 20 kV/cm. A modified theoretical model incorporating bias-field-dependent electron saturation velocity is employed to explain the results. It shows that GaAs:O exhibits a higher electron saturation velocity, which may be further exploited to generate even larger THz powers by reducing the ion dosage and optimizing the annealing process in GaAs:O.