Electron emission studies of nano-graphite clusters embedded in amorphous carbon films

The electron emission properties from carbon nanocomposite films deposited at elevated temperatures using pulsed laser deposition techniques have been studied. By using both Fowler-Nordhiem and Wentzel-Kramers-Brillouin approximation for electron tunneling, changes of the internal enhancement factors were studied. The internal enhancement ratios were found to have a ratio of β₁₀₀: β₄₀₀: β₇₀₀ = 1 : 1.46 : 2.02 for films deposited at 100°C, 400°C and 700°C respectively, thus showing that the enhancement was doubled when the temperature was increased in the range tested. High resolution XPS and TEM showed that both the formation of embedded nano-graphite clusters and an increase in the sp² bonded clusters were the main factors that enhanced electron emission. From electric field versus anode-cathode distance curves, we have determined our films to have an emission mechanism akin to carbon nanotubes, confirming the presence of conductive channels within the films.