High-quality nonpolar 4H-AlN grown on 4H-SiC (1120) substrate by molecular-beam epitaxy

摘要

Growth of very high-quality nonpolar (1120) a-plane face 4H-AlN on 4H-SiC (1120) substrate was investigated. Nonpolar 4W-AlN (1120) was isopolytypically grown on 4H-SiC (1120) 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 ? scan of the 4H-AlN layer was 40 arc sec. Transmission electron microscopy revealed the stacking fault density to be 2X10~5 cm~(-1), and the partial and perfect threading dislocation densities to be 7 X 10~7 and 1 X 10~7 cm~(-2), respectively.