Enhancement of initial layer‐by‐layer growth and reduction of threading dislocation density by optimized Ga pre‐irradiation in molecular‐beam epitaxy of 2H‐AlN on 6H‐SiC(0001)

Abstract

Abstract300‐nm‐thick AlN layers without a nucleation layer were grown on 6H‐SiC (0001) vicinal substrates with 3‐bilayer‐height steps by rf‐plasma‐assisted molecular‐beam epitaxy. A Ga beam was supplied for 0 to 30 seconds just before growth of AlN. The Ga pre‐irradiation for 7 seconds (∼1.6 ML) was found to be effective for realization of the AlN layer‐by‐layer growth mode at an earlier stage of the growth and reduction of threading dislocation densities (TDD) in the AlN layers. The screw‐type and edge‐type TDDs were ∼106 cm‐2 and 6×108 cm‐2, respectively. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)