Influence of the misorientation of 6H–SiC substrate on the quality of GaN epilayer grown by MOVPE

The effect of misorientation of 6H–SiC substrate on the structural quality of GaN epilayer grown by organometallic vapor phase epitaxy (MOVPE) has been investigated. The results reveal that the structural quality of GaN epilayer is significantly influenced by the misorientation of 6H–SiC substrate. Larger misorientation angle of 6H–SiC substrate results in better structural quality of GaN epilayer, such as narrower atomic step widths of GaN surface, less yellow luminescence band/edge emission ( I y / I b ) ratio of PL, and lower dislocations density. It is also found that the I y / I b ratio of GaN epilayer is affected only by the misorientation angle of 6H–SiC substrate, but the screw dislocation density and edge dislocation density are influenced by both the misorientation angle and the misorientation direction of 6H–SiC substrate. GaN epilayer grown on 6H–SiC substrate with 2.3° misorientation angle towards [ 1   1   2 ¯   0 ] direction has the best structural quality.