Dependence of crystallographic tilt and defect distribution on mask material in epitaxial lateral overgrown GaN layers

We have investigated the dependence of crystallographic tilt and defect distribution on mask material in metalorganic chemical vapor deposition grown GaN layers formed utilizing an epitaxial lateral overgrowth (ELO) technique using x-ray diffraction and transmission electron microscopy. Crystallographic tilt in the ELO GaN layer was suppressed by changing the mask material from electron beam (EB)-evaporated SiO₂ to plasma enhanced chemical vapor deposition (PECVD) grown SiO₂ and PECVD SiN_x. Defect distribution also changes in accordance with mask materials. By depositing a thin PECVD SiN_x layer on the PECVD SiO₂ mask, the crystalline quality of the ELO layer changes from that used with the SiO₂ mask to that used with the SiN_x mask. These results suggest that the interface between the ELO GaN layer and the mask has a significant effect on crystallographic tilt and defect distribution. © 2000 American Institute of Physics.