Self-assembled growth of inclined GaN nanorods on (10−10) m-plane sapphire using metal–organic chemical vapor deposition

We report the self-assembled growth of inclined and highly ordered GaN nanorods on (10−10) m-plane sapphire by metal–organic chemical vapor deposition, without metal catalyst. To determine the growth mechanism we performed a systematic study of the effect of the SiH4 flow, V/III ratio, growth temperature and growth time on growth behavior, demonstrating that optimized parameters were required for the growth of nanorods with high aspect ratios. High resolution X-ray diffraction showed that the nanorods were inclined at an angle of 58.4° with respect to the substrate normal and followed a well-defined epitaxial relationship with respect to the on-axis plane of the nanorods, the (11–22) semipolar plane, and the (10−10) m-plane sapphire. Finally cathodoluminescence showed that the near band edge emission of the Si-doped nanorod was asymmetric and broad owing to the band filling effect resulting from high carrier concentration, compared to the undoped GaN. •Inclined and highly ordered GaN nanorods were grown on m-sapphire by MOCVD.•The growth of GaN nanorods on m-sapphire was very sensitive to the growth parameters.•The epitaxial relationship between GaN nanorods and m-sapphire was investigated.•Cathodoluminescence revealed the characteristics of the highly Si-doped GaN nanorods.