Weakening of interface for self-separation
PCT/EP2011/068015 METHOD FOR FABRICATING A FREE-STANDING GROUP III NITRIDE SUBSTRATE
GaN
sapphire
Single crystal  GaN plates grown on nano-column interface
3-5 um GaN Substrate
Plane of
Self-separation-->

V.Nikolaev, et al. Effect of nano-column properties on self-separation of thick GaN layers grown by HVPE Phys. Status Solidi C, 1-3 (2014) / DOI 10.1002/pssc.201300432
GaN quasi-bulks
Self-separated GaN slab with thickness 3 mm.
1.5 and 2 GaN plates cut from the slab
1.5  GaN plate after gridding and  polishing
M. G. Mynbaeva, et.al  Low-cost large-area GaN crystalline material (2014)
beta-Ga2O3 single crystals
beta-Ga2O3 plate for GaN epitaxy
XRD omega-scan FWHM(001) ~ 70 arcsec
Optical transmission of  beta-Ga2O3  
Optical transmission of  beta-Ga2O3