Efficient field emission from α- Fe2 O3 nanoflakes on an atomic force microscope tip

Abstract

Aligned arrays of flake-shaped hematite (α- Fe2 O3) nanostructure have been fabricated on an atomic force microscope (AFM) tip. They are created by simply heating an iron-coated AFM tip in ambience on a hot plate. These nanoflakes are characterized as α- Fe2 O3 single crystalline structures with tip radii as small as several nanometers and are highly effective as electron field emitters. With a vacuum gap of about 150 μm, field emission measurements of α- Fe2 O3 nanoflakes on AFM tips show a low turn-on voltage of about 400-600 V and a high current density of 1.6 A cm-2 under 900 V. Such high emission current density is attributed to the nanoscale sharp tips of the as-grown nanoflakes. Based on the Fowler-Nordheim theory, it is demonstrated the enhancement factor of α- Fe2 O3 nanoflakes on AFM tips is comparable to that of carbon nanotubes. Our findings suggest that α- Fe2 O3 nanoflakes are potentially useful as candidates for future electron field emission devices. © 2005 American Institute of Physics.