A variety of different possible donor and acceptor impurities have been implanted into GaN and annealed up to 1450 degrees C. S+ and Te+ produce peak electron concentrations less than or equal to 5 X 10(18) cm(-3), well below that achievable with Si+. Mg produces p-type conductivity, but Be+- and C+-implanted samples remained n type. No redistribution was observed for any of the implanted species for 1450 degrees C annealing. Much more effective damage removal was achieved for 1400 degrees C annealing of high-dose (5 X 10(15) cm(-2)) Si+ implanted GaN, compared to the more commonly used 1100 degrees C annealing.