Increased thermal budget for selectively doped heterostructures by employing AlAs/GaAs superlattices

The degradation of selectivity doped Al0.35Ga0.65As/GaAs heterostructures caused by rapid thermal annealing (RTA) was studied. The samples were annealed for 30 s at temperatures between 600 °C and 850 °C. Thereafter, the samples were characterized by Hall measurements at room temperature. Conventional heterostructures with a random alloy Al0.35Ga0.65As spacer and donor layer show a strong degradation for annealing temperatures of 650 °C or higher. For heterostructures employing a stoichiometric equivalent short period superlattice (SPS) in spacer and donor region only a slight degradation was found for annealing temperatures up to 850 °C. As reason for the increased thermal stability, the suppression of As loss during the annealing by the SPS was identified.