Postannealing effect of GaN on reactive ion beam pre-treated sapphire

Abstract

Previous study showed that the reactive ion beam (RIB) pretreatment of sapphire prior to CaN deposition results in the reduction of dislocation density in GaN film. Also there was all amorphous phase remaining at the interface region after the GaN deposition at high temperature. Postannealing process was employed to see the structural change due to the recrystallization (if thc remaining amorphous phase, and the postannealing effect on electrical property of the GaN thin film oil RIB treated sapphire (0001) substrate. FWHM of DCXRD spectra all hall mobility of the Specimen showed the variation with the various postannealing time at 1000 degreesC in N-2 atmosphere. For the postannealed specimen, FWHM of DCXRD reduced about 50arc-sec and the mobility increased about 80 cm(2)/V-sec. The postannealed specimen with the best mobility was compared with not annealed sample by TEM and observe the decrease of lattice strain and reduction of dislocation density about 56 similar to 59 %. The present results clearly show that the combination of RIB pretreatment and proper post annealing conditions results in the improved properties of GaN films grown by MOCVD.