Defect reduction in (11¯00) m-plane gallium nitride via lateral epitaxial overgrowth by hydride vapor phase epitaxy

This letter reports on extended defect density reduction in $m$ -plane $\left(1\overline{1}00\right)$ GaN films achieved via lateral epitaxial overgrowth (LEO) by hydride vapor phase epitaxy. Several dielectric mask patterns were used to produce 10 to 100 μm-thick, partially and fully coalesced nonpolar GaN films. X-ray rocking curves indicated the films were free of wing tilt. Transmission electron microscopy showed that basal plane stacking fault (SF) and threading dislocation (TD) densities decreased from ${10}^5{\mathrm{cm}}^{-1}$ and ${10}^9{\mathrm{cm}}^{-2}$ , respectively, less than $3\times {10}^3{\mathrm{cm}}^{-1}$ and $\sim 5\times {10}^6{\mathrm{cm}}^{-2}$ , respectively, in the Ga-face (0001) wing of the LEO films. SFs persisted in $⟨0001⟩$ -oriented stripe LEO films, though TD reduction was observed in the windows and wings. Band-edge cathodoluminescence intensity increased 2 to 5 times in the wings compared to the windows depending on the stripe orientation. SFs in the low TD density wings of $⟨0001⟩$ -stripe films did not appear to act as nonradiative recombination centers.