Self-Separation of Freestanding GaN from Sapphire Substrates by Hydride Vapor Phase Epitaxy

Freestanding GaN wafers were produced by a newly developed self-separation method. Thick GaN layers were grown using hydride vapor phase epitaxy on a sapphire substrate with GaN seeds. The separation of the thick GaN layers took place during the growth sequence at the interface of GaN/sapphire, because of thermal stress and lattice mismatch between GaN and sapphire. The size of the freestanding GaN wafers was 23 mm x 22 mm. The threading dislocation density at the top surface was 10 6 cm -2 to ∼10 7 cm -2 .