Electron transport across nanocrystalline diamond films: Field emission and conducting atomic force microscopic investigations

In this paper, we report synthesis of nano-crystalline diamond (n-C diamond) films using DC-plasma assisted hot filament chemical vapor deposition. The films are characterized by Raman spectroscopy, scanning electron microscopy, and atomic force microscopy. The films were found to be uniform and well adherent to crystalline ⟨100⟩ and ⟨111⟩ on silicon substrates. Comparative studies were carried out using field emission microscopy and conductive atomic force microcopy to investigate the mechanism of electron transport across the n-C diamond films in far field and near field geometries. The former is important in the context of field emission display devices, and the latter is important as a gate electrode for field effect transistors. The I–V characteristics in both the cases obeyed the Fowler–Nordheim equation. Various parameters, viz., turn-on voltage, threshold voltage, and field enhancement factors, were estimated. The power spectral density of noise in field electron emission current exhibited P(f) = A·I2/f2 behavior. The results are discussed in the light of the present understanding of the mechanism of field emission from n-C diamond films.