Highly-crystalline 6 inch free-standing GaN observed using X-ray diffraction topography

We demonstrate the crystal quality of a 6 inch (0001) plane free-standing GaN substrate grown using a Na-flux based liquid phase epitaxy method. The 11 (2) over bar4 rocking curve profiles of every point over the substrate were recorded by synchrotron X-ray diffraction topography. The reconstructed images show that there is a huge boundary between the high crystalline area and the low crystalline area in the substrate. Anisotropic bowing of the lattice planes with respect to the [10 (1) over bar0] direction was obtained from wafer bending analysis. The mean width of the rocking curves over the wafer was 0.024 degrees, which indicates that the newly fabricated 6 inch GaN substrate was almost a single crystal. We found that there was a competition between crystallinity and homogeneity.

Automated summary

The crystal quality of a 6 inch free-standing GaN substrate grown using a Na-flux based liquid phase epitaxy method was demonstrated by recording rocking curve profiles and analyzing lattice plane anisotropic bowing. The competition between crystallinity and homogeneity was observed in the substrate, with a mean rocking curve width of 0.024 degrees indicating almost single crystal quality.