Growth of Catalyst-Free Hexagonal Pyramid-Like InN Nanocolumns on Nitrided Si(111) Substrates via Radio-Frequency Metal-Organic Molecular Beam Epitaxy

Hexagonal pyramid-like InN nanocolumns were grown on Si(111) substrates via radio-frequency (RF) metal-organic molecular beam epitaxy (MOMBE) together with a substrate nitridation process. The metal-organic precursor served as a group-III source for the growth of InN nanocolumns. The nitridation of Si(111) under flowing N-2 RF plasma and the MOMBE growth of InN nanocolumns on the nitrided Si(111) substrates were investigated along with the effects of growth temperature on the structural, optical, and chemical properties of the InN nanocolumns. Based on X-ray diffraction analysis, highly <0001>-oriented, hexagonal InN nanocolumns were grown on the nitride Si(111) substrates. To evaluate the alignment of arrays, the deviation angles of the InN nanocolumns were measured using scanning electron microscopy. Transmission electron microscopy analysis indicated that the InN nanocolumns were single-phase wurtzite crystals having preferred orientations along the c-axis. Raman spectroscopy confirmed the hexagonal structures of the deposited InN nanocolumns.