Scanning tunnelling microscopy (STM) and current imaging tunnelling current spectroscopy (CITS) methods were performed on polycrystalline diamond films grown on silicon substrates grown by microwave plasma-enhanced chemical vapour deposition. Large tunnelling currents were observed at some grain boundaries and crystal surfaces with secondary grains. Following atomic force microscopy (AFM) measurements, we performed scanning probe contact current (SPCC) measurements to investigate the spatial variation of electrical resistance on the surface by using an AFM cantilever in contact mode. The conducting grain boundaries and facets were observed on both boron-doped and undoped samples. For microscale characterization of the field emission properties, we performed scanning probe field emission current (SPFEC) measurements. From the results of STM/CITS, AFM/SPCC and SPFEC, it is concluded that the specific grain boundaries and facets on polycrystalline diamonds work as initial points of electron emission and cause high field emission current through a conducting pass formed in the bulk.

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Nitrogen-doped chemical vapour deposited diamond-like carbon (DLC) films were treated by reactive ion etching system under various conditions of CHF 3 gas successively after pre-treatment with oxygen. Atomic force microscopy and Raman spectroscopy were carried out in order to characterize the surface morphology and chemical bond, respectively. Scanning tunnelling microscopy was used in order to investigate the surface state of the DLC films at the nanoscale level. Scanning probe field emission current measurement was performed in order to obtain the emission current mapping. The emission sites appeared to a great extent after the surface treatment by CHF 3 gas and a clear activation effect was observed. We confirmed that the surface treatment using CHF 3 gas affected not only the appearance of emission sites but also the activation process.

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