An optical investigation of implantation damage as GaAs superlattices

Abstract

In this work tunability, implantation damage and recovery of GaAs doping superlattices implanted with hydrogen ions were studied. The applicability of two models of the optical properties of semiconductors was also investigated. GaAs doping superlattices were implanted with 0.5 MeV hydrogen ions at doses of 1012 cm-2, 1014 cm-2 and 1016 cm-2. This gradually modifies their optical characteristics from superlattice behaviour to something resembling the bulk material and beyond. Such a processing technique therefore provides a convenient way of tuning the optical properties of a superlattice semi-permanently. A combined result of ellipsometry and near infrared reflectance measurements showed that a single effective oscillator as well as a more advanced three-parameter model could be applied to the virgin and ion-implanted doping superlattices. This allowed us to determine the dose dependent effective band gap as well as other model parameters. Photoluminescence as well as normal and resonance Raman techniques were applied to study hydrogen ion implantation damage and its recovery. These techniques showed that implantation damage could be reversed to a large extent by a simple thermal annealing step.