Effect of the Ti-nanolayer thickness on the self-lift-off of thick GaN epitaxial layers

The effect of the type of substrate, sapphire substrate (c- and r-orientation) or GaN/Al$_2$O$_3$ template (c- and r-orientations), on the nitridation of an amorphous titanium nanolayer is shown. The effect of the titanium-nanolayer thickness on thick GaN epitaxial layer self-separation from the substrate is revealed. The titanium-nanolayer thickness at which thick GaN layer is reproducibly self-separated is within 20–40 nm.