Ca and O ion implantation doping of GaN

p- and n-type doping of GaN have been realized by ion implantation of Ca and O, respectively. Rapid thermal annealing at 1100 degrees C or higher is required to achieve p-type conduction in Ca or Ca+P implanted samples with an estimated ionization level of 169 meV and a corresponding activation efficiency of similar to 100%. This is the first experimental report of an acceptor species in GaN, other than Mg, with an ionization energy level less than 180 meV. O-implanted GaN displays an ionization level of similar to 29 meV but with an activation efficiency of only 3.6% after a 1050 degrees C anneal that may result from insufficient vacancy generation for the Lighter O ion or from the existence of a second, deeper O energy level. Neither Ca or O displayed measurable redistribution, based on secondary ion mass spectrometry measurements, even after a 1125 degrees C anneal. (C) 1996 American Institute of Physics.