Strong THz emission from an LTG-GaAs/n-GaAs/SI-GaAs epitaxial layer

Band structure engineering was employed on a conventional low-temperature-grown Gallium Arsenide (LTG-GaAs) grown on a semi-insulating (SI) GaAs with undoped GaAs buffer (LTG-GaAs/GaAs/SI-GaAs) to enhance its terahertz (THz) emission. Instead of a thick undoped GaAs buffer layer, a thin n-doped GaAs (n-GaAs) buffer layer was grown to increase the depletion field of the sample. Strong photocurrent surge effect from the surface and interface field of the LTG-GaAs/n-GaAs/SI-GaAs epitaxial layer resulted to a THz time domain spectroscopy (TDS) signal that is even higher than bulk n-doped Indium Arsenide (n-InAs), which is known to be a strong THz surface emitter.