HIGH RESISTIVE LAYER FORMATION BY Ga FOCUSED ION BEAM IMPLANTATION INTO GaAs AND ITS APPLICATION TO OPTICAL DEVICES.

Maskless focused ion beam (FIB) implantation is the most attractive method for fabricating very fine pattern in semiconductors. Among many liquid metal ion sources used in FIB implantation, Ga ion source is the most stable one with the longest life time. Recently, it was found that Ga FIB implantation into GaAs made n** plus or p** plus GaAs epilayer high resistive. Especially, this high resistivity is maintained after annealing as high as 800 degree C for n** plus epilayers. This is because the Ga implanted region becomes highly resistive p-type ( pi -type) after annealing. In this paper electrical properties of GaAs epilayer after Ga implantation are reported. Further, applications to optical devices are demonstrated.