We investigate the influence of nitridation on the growth of GaN films
. We present undoped alpha- and beta-GaN on 3C-SiC coated Si (0 0 1) w
ith and without nitridation, respectively, using radio frequency plasm
a assisted molecular beam epitaxy. In the case without nitridation, th
e RHEED (2 x 2) streak pattern at both [1 0 0] and [1 1 0] azimuths sh
ows that the high-quality zinc blende GaN films are grown. The X-ray d
iffraction (XRD) shows that (0 0 2) zinc blende GaN is observed at 2 t
heta = 39.53 degrees. At 10 K, PL of the zinc blende GaN is dominated
by band edge emission at 3.362 eV. On the other hand, alpha-GaN films
are obtained it nitridation that exhibit the (0 0 0 2) wurtzite GaN pe
ak at 34.25 degrees in the XRD measurement.