Epitaxial growth of p-InAs on GaSb with intense terahertz emission under 1.55-μm femtosecond laser excitation

Highlights: • Faceted p-InAs film generated twice stronger terahertz signal than p-InAs bulk. • A growth interruption scheme to resolve adhesion issue of epilayer is demonstrated. • The photo-Dember THz emission is explained by a large effective surface area. • A wide THz bandwidth of p-InAs film suggests high-velocity photocarriers. • 1.55 μm fs laser-excited p-InAs film exhibits lower saturation fluence than bulk. - Abstract: We report the molecular beam epitaxy growth of high-quality p-InAs thin films evaluated in the context of 1.55 μm femtosecond laser-excited THz emission efficiency. The presence of p-InAs is confirmed via scanning electron microscopy and X-ray diffraction. Using a GaAs buffer layer, the epitaxial growth of p-InAs layers was successfully achieved. Initiating GaAs deposition by growth interruption, we find that GaAs adheres to the GaSb substrate and provides a quasi-planar surface for the subsequent layers. We also find a significant enhancement in the THz radiation intensity of p-InAs films that is approximately twice compared to that of bulk p-InAs for 1.55 μm wavelength.