Previous studies showed that reactive ion beam (RIB) pretreatment of sapphi
re prior to GaN deposition results in the reduction of dislocation density
in the GaN film. It was also found that an amorphous phase remained at the
interface region after the GaN deposition Lit high temperature. Annealing w
as performed to obtain the structural change due to the recrystallization o
f the remaining amorphous phase, and the effect on the electrical propertie
s of the GaN thin film on RIB treated sapphire (0001) substrate. DCXRD spec
tra and Hall mobility of the specimen were studied as a function of the ann
ealing time at 1000 degreesC in N-2 atmosphere. For the annealed specimen.
FWHM of DCXRD decreased and the mobility increased. The annealed specimen w
as compared with a not annealed sample by TEM. A decrease of lattice strain
and a reduction of the dislocation density about 56-59% was observed. The
present results clearly show that the combination of RIB pretreatment and p
roper post annealing conditions improve the properties of GaN films grown b
y MOCVD.