Investigation of the crystal tilts in laterally epitaxial overgrowth GaN films formed by hydride vapor phase epitaxy

Tilting in hydride vapor phase epitaxy grown GaN films fabricated by lateral epitaxial overgrowth (LEO) technique has been investigated using four-circle X-ray diffraction measurements and scanning electron microscopy. Both growth rate and V/III ratio influence this tilt. High growth temperatures result in increased wing tilt. For high V/III ratios, above 10.8, a high growth rate is the main factor leading to increased tilt. For V/III ratios below 10.8, a lower V/III ratio decreases the tilt in LEO GaN because of the presence of excess Ga on the growth front resulting in a change of facet direction. Introduction of additional HCl to the surface of the substrate reduces the wing tilt. The mechanism of the influences of these growth conditions on wing tilt was discussed in detail.