Surface structure and electric properties of nitrogen incorporated NCD films

Linear characteristics were shown in I-V curves for nanocrytalline diamond (NCD) films deposited in a nitrogen rich atmosphere by microwave plasma chemical vapor deposition (MPCVD). In order to figure out how grain size, fraction and structure of N incorporated NCD films influence the electric performances of NCD films, the scanning electron microscopy (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were applied. Different surface morphologies are shown while the nitrogen concentration was varied. A similar tendency of electrical conductivity change versus grain size decrease and grain boundary network increase in NCD films has been observed. C1s core-energy, N1s core-energy and Raman spectra showed that the fraction and the chemical bonds of carbon atoms varied when the N2 concentration in plasma was different. All these measurements indicate that N2 concentration in plasma is a critical parameter for the growth, grain size, chemical bond and the electrical performance of deposited NCD films.