Local electron field emission characteristics of pulsed laser deposited diamondlike carbon films

Local electron field emission properties of diamondlike carbon (DLC) films were measured by a probe method in 1 atmosphere ambient pressure, using the modified scanning tunneling microscopic (STM) system, and the diode method. In the STM probe method, the field emission was turn on at a low bias as +2.67 V. A large emission current of 40 nA was attained at +7 volt bias voltage and the emission current density was estimated as Jt=5 A/cm2. By contrast, the current–voltage (I–V) characteristics of the same DLC films measured by diode method in 10−6 Torr ambient pressure revealed that the electron field emission was produced for a 13.2 V/μm electric field, and a high emission current density of J=160 μA/cm2 was obtained for a E=20 V/μm electric field. The geometrical enhancement factor (α), evaluated from the Fowler–Nordheim plot was around α=30, which is larger than what would be expected from a planar surface. This can be interpreted as the evidence that electrons are emitted locally from spherical SP3 clusters.