Electron field emission from nanotube and other carbon containing films

The ultimate material for electron field emission are nanotubes. Their high aspect ratio leads to a pronounced field enhancement at the apex and hence, electrons can be extracted at very low fields. We succeeded in the deposition of nanotube films on silicon substrate by a plasma enhanced CVD microwave deposition by using a methane (1%) hydrogen (99%) mixture at a pressure of 40 mbar and at a temperature of 950/spl deg/C (these conditions are very similar to what is used in standard diamond CVD). These films are very pure (no other carbon allotropes) and show electron emission around 1 V//spl mu/m with an emission site density up to 10/sup 5/ cm/sup -2/ at 3 V//spl mu/m. We characterized the films by HRSEM and TEM and measured their emission characteristics by taking I/V curves and energy resolved measurements of the field emitted electrons.