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