Negative Differential Conductance Observed in Electron Field Emission from Band Gap Modulated A-C Nanolayers

The field emission properties of an amorphous carbon (a-C) based quantum well structures are investigated. The a-C nanolayers are grown by pulsed laser ablation of a graphite target on highly doped n-type (100) Si wafers. The band gap of these layers are modulated through laser fluence variation. A negative differential conductance peak at 15 V/mum (F
_p
) and an abrupt increase in emission current at 25 V/mum (F
_s
) are observed. An analysis of these anomalous properties is made