ENHANCED COMPOSITIONAL DISORDERING OF QUANTUM-WELLS IN GAAS/ALGAAS AND INGAAS/GAAS USING FOCUSED GA+ ION-BEAMS

Spatially selective compositional disordering induced by focused Ga+ ion beam implantation in GaAs/AlGaAs and strained InGaAs/GaAs quantum well structures has been studied using photoluminescence. We find that beyond a certain implantation dosage, the degree of intermixing imparted to a given quantum well saturates and may eventually decline as a result of damage to the semiconductor surface. We overcome this limitation by thermally annealing the sample after implantation to repair the crystalline surface. We show that multiple successive implants interspersed with rapid thermal anneals (RTAs) are successful in locally shifting the optical band gap of quantum wells by many times that attributed to a single implant and RTA.