Enhancement of terahertz emission of semi-insulating gallium arsenide via zinc oxide thin film surface modification

This study reports on the Terahertz (THz) emission of semi-insulating Gallium Arsenide (GaAs) substrate coated with Zinc Oxide (ZnO) thin film via spray pyrolysis. Using a reflection-mode THZ time domain spectroscopy (TDS), it was shown  that enhancement in the THZ emission was observed with ZnO-coated SI-GaAs compared to the bare substrate. The enhancement is partly attributed to the decreased reflectivity due to the  modification of the surface by addition of a ZnO thin film on the GaAs substrate which translates to higher photon absorbance of the material.