Growth and Characterization of GaN Nano-Columns Grown on Gallium-Coated Si (111) by Using Molecular Beam Epitaxy

Vertically-aligned gallium-nitride nano-columns were grown on a gallium-coated silicon substrate by using molecular beam epitaxy. The dense packing of the nano-columns gives them the appearance of a continuous lm in a surface view, but a cross-sectional analysis shows them to be isolated nanostructures possessing a pyramid like tip. The diameter and the length of the GaN nano-columns were about 100 nm and 0.7 { 1 m, respectively. From the photoluminescence measurement of nanocolumns, a narrow peak at 363 nm with a full width at half maximum of 63 meV related to excitonic emission was observed. From the Raman spectrum, the phonon peak at 566.9 was assigned to the E2 phonon mode of GaN, which clearly indicates that the GaN nano-columns are well grown. From the above result, it is evident that the grown nano-columns are highly crystalline and are aligned perpendicular to the silicon surface.