Effect of TiO2 nanotube parameters on field emission properties

The dependence of field emission properties of titanium dioxide (TiO2) nanotubes (NTs) has been studied as a function of NT diameter (D) and height (h), which varied in the ranges 18-500 nm and 500-12 000 nm, respectively. The studies showed a strong dependence of the field emission on these parameters. With an increase of NT diameter, the field enhancement factor increased monotonically from 120 to 3800; the current density also increased until D = 320 (current density ∼ 3.8 mA cm-2), with subsequent decrease for larger diameters. The field emission properties initially improved with NT height until h = 5 μm, and later remained unchanged with further increases in h.