Ion implantation into III-V nitride materials is an important technology fo
r high-power and high-temperature digital and monolithic microwave integrat
ed circuits. We report the results of the electrical, optical, and surface
morphology of Si ion-implanted GaN films using furnace annealing. We demons
trate high sheet-carrier densities for relatively low-dose (n(atoms) = 5 x
10(14) cm(-2)) Si implants into AlN/GaN/sapphire heteroepitaxial films. The
samples that were annealed at 1150 degrees C in N-2 for 5 min exhibited a
smooth surface morphology and a sheet electron concentration n(s) similar t
o 9.0 x 10(13) cm(-2), corresponding to an estimated 19% electrical activat
ion and st 38% Si donor activation in GaN films grown on sapphire substrate
s. Variable-temperature Hall-effect measurements indicate a Si donor ioniza
tion energy similar to 15 meV.