Advantages and remaining issues of state-of-the-art m-plane freestanding GaN substrates grown by halide vapor phase epitaxy for m-plane InGaN epitaxial growth

Advantages and remaining issues of state-of-the-art m-plane freestanding GaN (FS-GaN) substrates grown by halide vapor phase epitaxy (HVPE) for m-plane InGaN epitaxial film growth by metalorganic vapor phase epitaxy are described. Because of the low threading dislocation and basal-plane stacking fault densities, improved quantum efficiency and short radiative lifetime are achieved for the near-band-edge emission of 200–250 nm thick m-plane pseudomorphic InGaN epilayers. As the surface flatness is greatly improved, the In-incorporation efficiency is lower than the cases for conventional c-plane growth and m-plane growths on due to the reduction in the area of inclined and tilted planes. Sub-micrometer-wide zonary patterns parallel to the c-axis and 2 μm long axis figure-of-eight patterns parallel to the a-axis are clearly visualized in the monochromatic cathodoluminescence (CL) intensity images.