Study of field electron emission from nanocrystalline diamond thin films grown from a N-2/CH4 microwave plasma

Nitrogen containing nanocrystalline diamond films have been synthesized by microwave plasma enhanced chemical vapour deposition using N-2/CH4 as the r eactant gas. The films prepared under different N-2/CH4 flow ratios were st udied by scanning electron microscopy, transmission electron microscopy, x- ray diffraction and secondary ion mass spectroscopy. Their field emission c haracteristics, i.e. both the distribution of the emission sites and curren t-voltage characteristics, were recorded using a transparent anode techniqu e. It was found that the grain size of films prepared under different condi tions varies and has a relationship with their turn-on fields. A possible e xplanation is given, which proposes that nanocrystalline boundary induced d efect states might affect the field emission characteristics.