Growth of Strain Free GaN Layers on (0001) Oriented Sapphire by Using Quasi-Porous GaN Template

We report the reduced-strain gallium-nitride (GaN) epitaxial growth on (0001) oriented sapphire by using quasi-porous GaN template. A GaN film in thickness of about 1 μm was initially grown on a (0001) sapphire substrate by molecular beam epitaxy. Then it was dealt by putting into 45% NaOH solution at 100°C for 10 min. By this process a quasi-porous GaN film was formed. An epitaxial GaN layer was grown on the porous GaN layer at 1050°C in the hydride vapour phase epitaxy reactor. The epitaxial layer grown on the porous GaN is found to have no cracks on the surface. That is much improved from many cracks on the surface of the GaN epitaxial layer grown on the sapphire as the same as on GaN buffer directly.