Impurity induced layer disordering of Si implanted AlxGa1−xAs‐GaAs quantum‐well heterostructures: Layer disordering via diffusion from extrinsic dislocation loops

Extensive data are presented on impurity‐induced layer disordering (IILD) of AlxGa1−xAs‐GaAs quantum‐well heterostructures and superlattices that are Si implanted and annealed (Si+‐IILD) at three different implant doses. We show that impurity activation is not critical to the layer disordering process and that Si diffusion from the implanted profile initiates Si+‐IILD. When the implant dose is as high as φ≥5×1013/cm2 (nSi ≥2×1018/cm3), Si interstitial loops (Si‐ILs) form by diffusion and agglomeration of the implanted Si atoms during the initial stages of annealing. If a source of Ga vacancies is provided (e.g., via an As overpressure or SiO2 encapsulation), the Si‐ILs dissociate and supply Si atoms for diffusion and hence Si+‐IILD during the latter stages of annealing. If a Si3N4 encapsulant is employed, however, fewer Si‐ILs form and Si diffusion is inhibited. For an implantation dose as low as φ=1×1012/cm2 (nSi =3×1016/cm3), extensive Si+‐IILD is realized via capless annealing and Si‐ILs are not observ...