Field Emission Behaviour of Single-Crystal Pd Nanowires

Single-crystal Pd nanowires with typically 100 nm diameters and lengths from several micrometers to tens of micrometers were grown on Al
2
O
3
substrates in a furnace with Ar atmosphere. Integral field emission measurements of such samples after Pd coating (~10 nm) were performed in a diode configuration with a 50
$\mu\mathrm{m}$
mica spacer in a vacuum chamber at pressures of about 10–
⁹
mbar. The IV measurement of the sample shows an integral emission current up to 2
$\mu \mathrm{A}$
at a voltage of 500 V (10 MV/m) and an onset voltage for a current of 1 nA of about 275 V. The corresponding Fowler-Nordheim plot show a linear behavior, like expected for a metal needle.