Hydrogen radical surface cleaning of GaAs for MBE regrowth

Modulation-doped GaAs/AlGaAs two-dimensional electron gas (2DEG) structures have been regrown on air-exposed GaAs buffer layers, at varying proximity to the regrowth interface. The degradation in 2DEG quality with decreasing separation from a hydrogen radical (H*) cleaned regrowth interface was found to be much reduced in comparison to that for a thermally cleaned interface. H* cleaning has allowed for the growth of a 2DEG lying only 50 nm from the regrowth interface with a mobility, after illumination, of 5.3 x 10(5) cm(2) V-1 s(-1) at a carrier concentration of 4.2 x 10(11) cm(-2), SIMS characterisation has been used to measure significant reductions in contamination at the regrowth interface at cleaning temperatures of 500 degrees C. Cathodoluminescence data, measured for a 5 nm quantum well lying 30 nm from the regrowth interface, further indicate the improved growth morphology achieved following H* cleaning, in comparison to that achieved by thermal decontamination.