Threading-dislocation blocking by stacking faults formed in an undoped GaN layer on a patterned sapphire substrate

The microstructure of an undoped GaN grown on a hemisphere-patterned sapphire substrate is characterized by transmission electron microscopy. Interestingly, basal-plane stacking faults are formed in GaN at the height of hemispheres, leading to a substantial reduction in threading-dislocation density. It is believed that the formation of the stacking faults is characteristic of the lateral growth mode. This study looks at an unexplored feature of the lateral growth behavior that both so-called epitaxial lateral overgrowth mechanism and stacking faults function to reduce the dislocation density for the GaN growth on hemisphere-patterned sapphire substrates.