N‐ andp‐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 5×1014cm−2of each element. Conversely, highly resistive regions (≳5×109&OHgr;/&laplac;) can be produced in initiallyn‐ orp‐ 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. ©1995 American Institute of Physics.