The GaN/substrate bi layer is cooled from {TAIL ~ a growth temperature} at which {HEAD ~ the bulk layer} is grown to an ambient temperature, wherein GaN material of the bi layer cracks laterally and separates from the substrate to form a substantially crack free free standing GaN article 
at is grown
The GaN / substrate bi layer is cooled from { TAIL ~ a growth temperature } at which { HEAD ~ the bulk layer } is grown to an ambient temperature , wherein GaN material of the bi layer cracks laterally and separates from the substrate to form a substantially crack free free standing GaN article
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL REL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH