• defects;
  • MOCVD;
  • nucleation;
  • transmission electron microscopy

With 100-nm-thick 3C-SiC intermediate layer, GaN layer of relative high quality was obtained on Si substrate by using a maskless epitaxial lateral overgrowth (ELO). The three-dimensional growth of maskless ELO process was investigated with wafer reflectance collected during growth. Low temperature cathodoluminescence observation confirmed the improvement of the GaN quality by ELO. An AlN interlayer was used to prevent crack of the GaN epilayer. As a result, the as-grown GaN layer shows a crack-free surface with long atomic steps. The threading dislocation density is lower than 1 × 109 cm−2 in GaN layer underneath AlN interlayer.