Fabrication of nanostructured indium nitride by PA-MOMBE

Nanostructured indium nitride (InN) films have been prepared on the c-plane sapphire substrate by a plasma-assisted metal–organic molecular beam epitaxy (PA-MOMBE) system. We have investigated the influence of growth temperature on the surface morphology and crystal structures by atomic force microscopy, scanning electron microscopy and energy dispersive spectroscopy. A pronounced two-dimensional growth mode was observed at a growth temperature of 500 °C, and these films showed high orientation along the c-plane. As the growth temperature reached 700 °C, (InN) 1D nanostructures were formed and exhibited randomly oriented crystalline nature. Furthermore, the enhancement of the indium atoms' surface mobility at high growth temperature might be crucial to the formation of InN nanonails and nanorods. Meanwhile, no metallic droplet was observed at the end of the nanostructured InN, which is the intrinsic feature of the vapor–liquid–solid method. These results indicate that the control of the growth condition is essential for engineering the growth of InN on Al₂O₃ (0 0 1), and it might also be applicable for other lattice-mismatched III–V heteroepitaxial systems.