Impact of III/V ratio on polytype and crystalline quality of AlN grown on 4H‐SiC (11$ \bar 2 $0) substrate by molecular‐beam epitaxy

The impact of the III/V ratio during growth on the polytype and crystalline quality of nonpolar AlN grown on 4H-SiC (110) was investigated. Growth of AlN was carried out by molecular-beam epitaxy (MBE) using elemental Al and rf-plasma excited nitrogen. Polytype replication from the SiC substrate to the grown AlN epilayer occurred under Al-rich conditions, i.e., 4H-AlN (110) was grown on 4H-SiC. On the other hand, the thermally stable 2H-AlN (110) polytype was grown under N-rich conditions. The best crystalline quality of AlN was obtained for slightly Al-rich conditions. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)