AlN缓冲层对Si基GaN外延薄膜性质的影响

Abstract

GaN epitaxial films with different thickness of AlN buffer layers were grown on Si( 111) by metal-organic chemical vapor deposition( MOCVD).The effects of AlN buffer thickness on inplane stress,surface morphology and crystal quality of GaN materials were investigated.It is observed that the AlN buffer with thickness of 15 nm can effectively suppress the diffusion of Si from the substrate.Moreover,the AlN buffer can also introduce a relatively large compressive stress to GaN layers and eliminate the crack.The crack-free and mirror-like GaN layer was obtained by depositing on the AlN buffer layer with thickness of 15 nm.The full width at half maximum of the film is as low as 536 arcsec for( 0002) and 594 arcsec for( 1012) reflection,the in-plane tension stress is 0.3 GPa,and the RMS roughness tested by atomic force microscopy is 0.2 nm.