N-plasma assisted molecular beam epitaxy of GaN(000(1)over-bar) thin films on 6H-SiC(000(1)over-bar)

On the atomically flat C-face 6H-SiC surface prepared by ultra high vacuum Si-etching, two-dimensional growth of GaN (000 (1) over bar) thin films is observed with an AIN buffer layer using N-plasma assisted molecular beam epitaxy. Scanning tunneling microscopy measurements reveal a series of Ga-stabilized reconstructions, which are consistent with the surface phases reported for the GaN (000 (1) over bar) film, but are different from that of the GaN(0001) surface. The result agrees with the polarity assignment of the heteroepitaxial wurtzite GaN films on polar 6H-SiC substrates, that is, a GaN film grown on Sic(000 (1) over bar) is (000 (1) over bar) oriented (N-face) while that on SiC(0001) is (0001) oriented (Ga-face).