GaN nanostructures were prepared on Si(111) by a hot-wall epitaxy technique employing the modified two-step growth method. Isolated hexagonal pillar-like GaN nanostructures (GaN nanopillars) with the typical diameter, height, and density of 200–300nm, 0.5–1μm, and 3–4×108cm−2, respectively, are self-organized without intentional pre-processing to the Si substrate. The photoluminescence and cathodoluminescence (CL) measurements show the strong near-band-edge emissions without the yellow band at room temperature. Stronger CL is obtained from the GaN nanopillars in comparison to single-crystalline GaN. The obtained strong CL is related to high crystal quality of the dislocation-free GaN nanopillars.

Improved GaN growth using a quasihot wall metal-organic chemical vapor epitaxy reactor

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A simple mixed source (gallium and indium metals) method was used in a hot-wall epitaxial system to grow InGaN films on sapphire with thick (∼1.5 µm) and thin (∼3 nm) GaN buffer layers. Indium incorporation was controlled independently by the substrate temperature, the N2 partial pressure and the mixed source temperature. High-quality InGaN films were obtained, showing strong near-band-edge emission peaks ranging from 370 to 465 nm and narrow X-ray rocking curve full-width at half maximum for InGaN (0002) of 7.03 arcmin. Non-resonant Raman shift of InGaN layers was clearly observed for the first time.