EVALUATION OF DISORDERING AT LOW DOPING CONCENTRATION IN SELECTIVELY SI-DOPED AL0.3GA0.7AS/GAAS HETEROINTERFACES

Compositional disordering in selectively Si-doped Al0.3Ga0.7As/GaAs heterostructures (SDH) at low doping concentration (≤2×1018 cm-3) was evaluated. The compositional distribution in the disordered region was directly observed by the CAT (Composition Analysis by Thickness-fringe) method with a high depth resolution of 0.5 nm. Furthermore, the disordering of an undoped superlattice (SL) as a result of Si diffusion from a doped layer was also observed carefully for various Si concentrations from 1 to 8×1018 cm-3. As a result, interdiffusion of SL's has been affected by the Si concentration also at low concentration. It is concluded that at low doping concentration the disordering is induced mainly by the diffusion of Si. © 1989.