Reduction of threading defects in GaN grown on vicinal SiC(0001) by molecular-beam epitaxy

We observe a significant reduction of threading dislocations in GaN grown o n vicinal substrates of SiC(0001). Using scanning tunneling microscopy, we find films grown on vicinal substrates maintain the surface misorientation of the substrate and display terraces with straight edges. On top of the te rraces there is no spiral mound, which is the main feature found for films grown on singular substrates. Transmission electron microscopy studies conf irm that threading screw dislocations are reduced by two orders of magnitud e while edge dislocations are reduced by one order. (C) 2000 American Insti tute of Physics. [S0003-6951(00)00934-7].