Abstract
In this work, we observed enhanced terahertz emission from the interface between indium tin oxide (ITO) and semi-insulating gallium arsenide (SI-GaAs) substrate. Further, we investigated the dependence of THz emission on pump power and angle of incident excitation beam. We found more than 3 times of THz emission power enhancement for incident angle below 70°. Besides, we found enhancement of THz radiation at low pump intensity and saturation with increasing peak excitation intensity beyond 20 TW/m. The experimental results are well explained by plasmonic effects at the metal-semiconductor interface.