HYDROGEN RADICAL SURFACE CLEANING OF GAAS FOR MBE REGROWTH

Modulation-doped GaAs/AlGaAs two-dimensional electron gas (2DEG) struc tures have been regrown on air-exposed GaAs buffer layers, at varying proximity to the regrowth interface. The degradation in 2DEG quality w ith decreasing separation from a hydrogen radical (H) cleaned regrowt h interface was found to be much reduced in comparison to that for a t hermally cleaned interface. H cleaning has allowed for the growth of a 2DEG lying only 50 nm from the regrowth interface with a mobility, a fter illumination, of 5.3 x 10(5) cm(2) V-1 s(-1) at a carrier concent ration of 4.2 x 10(11) cm(-2), SIMS characterisation has been used to measure significant reductions in contamination at the regrowth interf ace at cleaning temperatures of 500 degrees C. Cathodoluminescence dat a, measured for a 5 nm quantum well lying 30 nm from the regrowth inte rface, further indicate the improved growth morphology achieved follow ing H cleaning, in comparison to that achieved by thermal decontamina tion.