Liquid-encapsulated Czochralski (LEC) grown, undoped GaAs exhibits high resistive, semiinsulating property and is very suitable for high performance GaAs IC's substrate with a direct ionimplantation technology. An FET threshold voltage, however, is strongly influenced by material properties. A close relationship between dislocations, native antisite defects AsGa and FET threshold voltage is briefly discussed, and it is demonstrated that dislocation-free GaAs exhibits a very uniform electrical properties desirable for GaAs ICs substrate.
