N‐ and p‐type regions have been produced in GaN using Si+ and Mg+/P+ implantation, respectively, and subsequent annealing at ∼1100 °C. Carrier activation percentages of 93% for Si and 62% for Mg were obtained for implant doses of 5×1014 cm−2 of each element. Conversely, highly resistive regions (≳5×109 Ω/⧠) can be produced in initially n‐ or p‐ type GaN by N+ implantation and subsequent annealing at ∼750 °C. The activation energy of the deep states controlling the resistivity of these implant‐isolated materials is in the range 0.8–0.9 eV. These process modules are applicable to the fabrication of a variety of different GaN‐based electronic and photonic devices.