Enhancement- and depletion-mode AlGaAs/In0.15Ga0.85As HEMTs were fabricated on the same wafer by the selective ion implantation technique. This implantation results in extra carriers in the area of D-HEMTs, and therefore E- and D-HEMTs can be realised simultaneously after a single gate lithography step. As compared with the conventional approach, this selective ion implantation provides a convenient method for implementing the E/D-mode logic circuits for high-speed and low-power applications.