Improvement of the Quality of a GaN Epilayer by Employing a SiN_x Interlayer

GaN epilayers with a porous SiN_x interlayer were grown by metal-organic chemical vapor deposition on c-plane sapphire substrates. It is found that the crystalline qualities are significantly improved with SiN_x growth. The improvement is attributed to the reduction of the density of threading dislocations (TDs) by an over-growth process of GaN grown on a SiN_x interlayer. The influence mechanism of SiN_x interlayers on GaN growth mode is also discussed.