Abstract
Resistivity enhancement by 5 orders or more was realized by Ga focused ion beam implantation into n+ and p- GaAs epilayers. For originally n+ epilayers, this resistivity enhancement is maintained after annealing as high as 800°C. However this enhancement disappears after annealing at above 650°C for p+ epilayer. This property makes GaAs high resistive only in a limited area whose minimum dimension is 0.1 µm or less, and is attractive for a device fabrication process to electrically isolate integrated elements.