Defect reduction in (1 1 2̄ 0) nonpolar a-plane GaN grown on r-plane sapphire using TiN interlayers

We report on the use of TiN interlayer to reduce the threading dislocation density in nonpolar a-plane GaN material grown by metal organic chemical vapor deposition (MOCVD), where the interlayer was formed by depositing the Ti metal on a GaN template followed by nitridize. By means of high resolution X-ray diffraction, transmission electron microscopy, and atomic force microscopy analyses, we found that the nonpolar a-plane GaN epitaxial grown on 10 nm-thick TiN interlayer, both on-axis and off-axis, exhibits a significant reduction in the full width at half maximum, the basal plane stacking faults (BSF), the threading dislocation density, and the root-mean-square roughness, respectively.

► The TiN interlayer method has been used to grow nonpolar a-plane GaN by MOCVD.
► These results are much better than that with the traditional ELOG method.
► The two BSF decrease mechanisms block and annihilate are proposed.