In this work, free-standing GaN single crystalline crackless substrates were grown by hydride vapor phase epitaxy (HVPE). The GaN substrate, having a current maximum size of 350 μm thickness and 10 mm×10 mm area, were obtained by the HVPE growth of a thick-film GaN on a sapphire substrate. Subsequently, the sapphire substrate was removed. To grow the crack-free GaN on a sapphire substrate, cracks were intentionally generated only in the sapphire substrates after 100 μm thickness GaN growth, and then the GaN thick film was re-grown. The GaN single crystalline substrate prepared through this work was found to be optically and electrically superior to those of bulk GaN single crystals. The free-standing and crack-free GaN single crystalline substrate is suitable for the homoepitaxial growth of GaN.
Source: Journal of Crystal Growth