Hydrogen radical cleaning and low energy electron stimulated desorption of surface contaminants for MBE regrowth of GaAs

Modulation doped two-dimensional electron gas (2DEG) samples have been used to characterise the quality of epitaxial growth achieved within 400Åof a hydrogen radical (H*) cleaned GaAs regrowth interface. For planar ex-vacuo exposed substrates, regrowth of a high quality InGaAs/GaAs pseudomorphic 2DEG has been achieved at only 125Åfrom the cleaned interface. For patterned substrates, a GaAs/AlGaAs modulation doped 2DEG with a 1.5 K, dark mobility of 1 × 106cm2 V−1 s−1 at a carrier concentration of 8 × 1011cm−2 has been regrown at a separation of 375 Å after H* cleaning at 500°C. These results highlight the improved growth morphology which occurs following H* cleaning of the regrowth interface in comparison to that achieved using standard thermal decontamination. Static SIMS analysis shows that low energy electron irradiation at an energy of 100 eV may also be used as an alternative non-destructive method for contaminant reduction at an air exposed GaAs(100) surface.