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Grain sizes of the hot filament chemical vapor deposited diamond films were found to decrease from 3 µm to 15 nm with increase in substrate temperature during deposition from 1023 K to 1173 K respectively. These films were deposited on p‐type silicon (100) substrate using methane and hydrogen as reactant gases. Surface scanning electron micrographs of the deposited films confirmed that diamond grain size was strongly dependent on the substrate temperature. High resolution transmission electron microscope studies of the nanodiamond films showed lattice fringes corresponding to graphitic planes in the interface region between two diamond nanocrystallites. Field emission studies carried out in a diode geometry revealed that nanodiamond films were better emitters than microcrystalline films, which is attributed to increase in graphitic grain boundaries with decrease in grain size.
Our sincere thanks are due to Dr. K. Muraleedharan, Scientist, Defence Metallurgical Research Laboratory (DMRL), and the Director, DMRL for their support and encouragement to this work. The authors also thank Electron Microscopy Division, All India Institute of Medical Sciences, New Delhi for SEM studies. One of the authors, S.K. Arora is grateful to the Council of Scientific and Industrial Research, Government of India for a research fellowship.