Maskless lateral epitaxial overgrowth of high-aluminum-content AlxGa1−xN

We have demonstrated maskless lateral epitaxial overgrowth of Al0.96Ga0.04N on sapphire for dislocation reduction. 600 nm and 1 μm thick AlN layers were grown on sapphire via metalorganic chemical vapor deposition. Parallel, periodic trenches were then etched in the AlN and Al0.96Ga0.04N was regrown laterally from the unetched mesas. Significant threading dislocation reduction was observed for “wing” material, growing laterally, compared to “seed” material, growing vertically from the unetched mesa, as observed by atomic force microscopy, and transmission electron microscopy. Crystallographic wing tilt of ∼0.23° was measured by x-ray diffraction.