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+ i on beam implantation in GaAs/AlGaAs and strained InGaAs/GaAs quantum w ell structures has been studied using photoluminescence. We find that beyond a certain implantation dosage, the degree of intermixing impart ed to a given quantum well saturates and may eventually decline as a r esult of damage to the semiconductor surface. We overcome this limitat ion by thermally annealing the sample after implantation to repair the crystalline surface. We show that multiple successive implants inters persed with rapid thermal anneals (RTAs) are successful in locally shi fting the optical band gap of quantum wells by many times that attribu ted to a single implant and RTA.