Direct growth of Al nanowire arrays: Thermal expansion and field emission properties

The Al nanowire arrays. were directly deposited on the Si substrates by a facile electron-beam evaporation technique, oblique angle deposition. This process was accomplished by tilting the Si substrates and adjusting the incident angle of evaporated Al vapor flux from the normal of the substrates at 87 degrees. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy observations indicate that large-area and single-crystalline Al nanowire arrays are effectively fabricated. In situ high-temperature X-ray diffraction measurements show that Al nanowires have a smaller lattice constant and smaller thermal expansion coefficient compared with the Al film. The thermal expansion mechanism was discussed in detail. Our field emission results show that the Al nanowires might be potential field emitters in the future nanodevices.