Heteroepitaxy of Fin-Shaped InGaN Nanoridge Using Molecular Beam Epitaxy

We have demonstrated a well-ordered In-rich single crystalline InGaN nanoridge array grown on GaN/sapphire substrate using the integration of top-down etching and bottom-up molecular beam epitaxy. During the initial growth of InGaN on a patterned GaN/sapphire substrate, a (1011) r-plane predominantly forms, suppressing the growth in [1011] crystal direction and resulting in a triangular InGaN nanoprism. As the growth proceeds further, a narrow (∼50 nm) single-crystal fin-shaped InGaN nanoridge forms atop the InGaN nanoprism structure. The resulting narrow fin-shaped InGaN nanoridge structure shows extremely strong photoluminescence (PL) intensity with a center wavelength at 524–560 nm and narrow distribution compared to the epitaxially grown planar InGaN layer or InGaN nanowire. High-resolution scanning transmission electron microscopy (STEM) combined with an energy-dispersive X-ray (EDS) map reveals that a sharply faceted single-crystal InGaN nanoridge (∼50 nm width) forms along the top of each InGaN n...