LT GaAs delta-doped with In: enhanced As excess, In-Ga intermixing, As cluster array ordering

The effects of indium incorporation in GaAs grown by MBE at low substrate temperature (LT GaAs) have been studied. The 0.04% indium doping is shown to provide an increase in the As excess along with improved crystal quality. The In-Ga intermixing is found to enhance by almost two orders of magnitude due to a high point defect concentration in LT GaAs. The effective activation energy of the intermixing is determined from TEM measurements to be 1.1 eV. The As precipitation kinetics is found to be quicker in In-free regions than within the In-containing layers. Using these observations, we successfully formed a 30 nm period perfect superlattice consisting of thin (double cluster diameter) As cluster sheets separated by cluster-free LT GaAs spacers