High-quality nonpolar 4H-AlN grown on 4H-SiC (112¯) substrate by molecular-beam epitaxy

Abstract

Growth of very high-quality nonpolar (112¯0) a-plane face 4H-AlN on 4H-SiC (112¯0) substrate was investigated. Nonpolar 4H-AlN (112¯0) was isopolytypically grown on 4H-SiC (112¯0) substrate by molecular-beam epitaxy. A reduction of defects such as stacking faults and threading dislocations was achieved by keeping the growing surface flat. To this end, the SiC substrate was HCl gas etched and the V/III ratio was optimized for AlN growth. A full width at half maximum of symmetrical x-ray diffraction ω scan of the 4H-AlN layer was 40arcsec. Transmission electron microscopy revealed the stacking fault density to be 2×105cm−1, and the partial and perfect threading dislocation densities to be 7×107 and 1×107cm−2, respectively.