Doping and defect control of ferromagnetic semiconductors formed by ion implantation and pulsed-laser melting

We demonstrate a simple but effective route for the synthesis of ferromagnetic semiconductors that combines Mn ion implantation (II) and pulsed-laser melting (PLM). By this process Ga 1− x Mn x As films exhibiting a ferromagnetic Curie temperature ( T C) exceeding 130 K have been synthesized. These materials possess electrical and magnetic characteristics similar to molecular beam epitaxy-grown (MBE-grown) films that are tunable through experimental parameters such as implantation dose, laser energy fluence, and co-doping with Te donors. We have also used II–PLM to form ferromagnetic single-crystalline Ga 1− x Mn x P films. These films display magnetic properties similar to their arsenide counterparts despite remaining non-metallic and becoming strongly insulating at low temperatures. Unlike as-grown MBE films, both Ga 1− x Mn x P and Ga 1− x Mn x As formed by II–PLM do not contain Mn at interstitial sites; instead, non-substitutional Mn atoms are found to be randomly located, perhaps as clusters. As a result, post-PLM thermal annealing at temperatures higher than 300 °C leads to a decrease in T C as Mn atoms leave substitutional sites.