Field emission characteristics of CVD diamond thin films with SnO/sub 2/ as overlayer

We have studied the field emission characteristics of CVD diamond thin films deposited on silicon substrate with tin-oxide (SnO/sub 2/) as a overlayer. The diamond thin films were synthesized by Hot Filament Chemical Vapour Deposition (HFCVD) method. The SnO/sub 2/ coating on silicon substrate was prepared using Spray Pyrolysis technique. The field emission current-voltage (I-V) measurements were performed in ´diode´ configuration at base pressure 1/spl times/10/sup -8/ torr. The CVD diamond films with SnO/sub 2/ overlayer exhibit better emission characteristics as compared to the normal CVD diamond films. Appearance of more number of emission sites there by leading to higher emission current has been observed in case of CVD diamond films with SnO/sub 2/ overlayer. Also the turn-on voltage, required to draw 0.1 /spl mu/A current, for such films was found to be /spl sim/40% less than that of the normal CVD diamond films. The surface roughness revealed by Atomic Force Microscopy (AFM) is 4 nm and 4.5 nm for normal and CVD films with SnO/sub 2/ overlayer respectively. The formation of SnO/sub 2/ coating on silicon substrate and nucleation and growth of diamond have been confirmed by X-ray Diffraction (XRD) and Raman Spectroscopy observations.