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

The degradation of selectivity doped Al0.35Ga0.65As/GaAs heterostructures c aused by rapid thermal annealing (RTA) was studied. The samples were anneal ed for 30 s at temperatures between 600 degreesC and 850 degreesC. Thereaft er, the samples were characterized by Hall measurements at room temperature . Conventional heterostructures with a random alloy Al0.35Ga0.65As spacer a nd donor layer show a strong degradation for annealing temperatures of 650 degreesC or higher. For heterostructures employing a stoichiometric equival ent short period superlattice (SPS) in spacer and donor region only a sligh t degradation was found for annealing temperatures up to 850 degreesC. As r eason for the increased thermal stability, the suppression of As loss durin g the annealing by the SPS was identified. (C) 2001 American Institute of P hysics.