Interruption-assisted epitaxy of faceted p-InAs on buffered GaSb for terahertz emitters

Abstract

We demonstrate molecular beam epitaxy growth of p-InAs layers on GaAs-buffered GaSb that may be suitable for terahertz applications. GaAs buffer deposition is initiated by applying growth interruption. Reflection high-energy electron diffraction shows that GaAs growth proceeds to a quasi-two-dimensional growth mode. The scheme allows growth of a p-InAs layer 600 nm to 1.0 µm thick. Growth performed without GaAs and growth interruption resulted in decomposition of the p-InAs. When the scheme is used, the ensuing p-InAs first follows quasi-two-dimensional growth before favoring faceted islanding. Under 800-nm-wavelength femtosecond laser excitation, the p-InAs layer generates terahertz signals 70% of that of bulk p-InAs.

THz pulse emission from InAs-based epitaxial structures grown on InP substrates

“…More convenient for THz-TDS set-ups would be surface emitters consisting of a thin epitaxial layer of InAs grown on a high-resistivity substrate of other semiconductors, which could be used in the transmission geometry. Emitters from epitaxially grown InAs layers on GaSb and GaAs substrates have already been demonstrated by several groups [6][7][8][9]. Despite the different level of lattice mismatch between the substrate and InAs, and different structural quality of the epitaxial layers (in [9] InAs layer was even polycrystalline), the THz radiation emitted after their excitation by femtosecond Ti:sapphire laser pulses was of comparable intensity or even more powerful than that obtained from bulk InAs crystals.…”