Growth of nonpolar AlN (11(2)over-bar0) and (1(1)over-bar00) films on SiC substrates by flow-rate modulation epitaxy

Nonpolar AlN (11(2)over bar0) and (1(1)over bar00) films were grown on SiC substrates by flow-rate modulation epitaxy (FME), wherein trimethylaluminum and NH3 were alternately supplied. FME provides both AlN (11(2)over bar0) and (1(1)over bar00) films with good crystallinity and smooth surfaces, whereas AlN (1(1)over bar00) films obtained by conventional metal-organic chemical vapor deposition exhibit poor crystallinity and rough surfaces with deep trenches consisting of (000(1)over bar) and (1(1)over bar01) N-face microfacets. FME effectively eliminates these trenches, because the microfacets are unstable and have faster growth rates because of the enhanced migration of Al atoms in the absence of excess N surface coverage under the Al-rich condition. (c) 2007 American Institute of Physics.