Successful natural stress-induced separation of hydride vapor phase epitaxy-grown GaN layers on sapphire substrates

This paper presents the behavior of GaN layers on sapphire substrates in successful natural stress-induced separation. It was revealed that a separation plane was formed in the middle of a hydride vapor phase epitaxy-grown GaN layer under specific conditions. One possible reason is that the proper temperature gradient produces a driving force for the separation during the cooling process. No dislocation and no cracks generated through the cooling process. As a result, a single piece of 2″ GaN wafer with a crack-free mirror surface was obtained. The full width at half maximum of X-ray rocking curve and dislocation density of the freestanding GaN wafer were less than 65 arcsec and 8×106 cm−2, respectively, indicating the high crystalline quality.

► A successful natural stress-induced separation was demonstrated in a HVPE process. ► A single piece of 2″ GaN wafer with a high crystalline quality was obtained. ► The separation plane formed inside the GaN layer. ► Temperature gradient produced a driving force for the separation during the cooling process.