Electron emission from diamond thin films deposited by microwave plasma-chemical vapor deposition method

Diamond films with different crystal structures, morphologies and surface c haracteristics were synthesized under various deposition parameters and ann ealing conditions by the microwave plasma chemical vapor deposition (MWPCVD ) method using gas mixtures of CH4, CO and H-2. The effects of CH4 concentr ations, grain sizes, grain orientations, film thicknesses and annealing tec hnologies in various ambient gases on planar electron emission of diamond f ilms were studied. The results show that small-grained and (011)-oriented d iamond films deposited under the condition of high CH4 concentration presen t the properties of high emission current and low threshold voltage; the em ission current increases with decreasing the film thickness. There are larg est current density and lowest threshold voltage at the film thickness of 1 .5 mu m. The annealing in H-2 after deposition appears to be more beneficia l in lowering the threshold voltage, increasing emission current and improv ing stability for electron emission of films than annealing in N-2 or Ar. T hese results indicate that diamond thin films with high emission current, l ow threshold voltage and high stability can be obtained by selecting suitab le deposition parameters of diamond films. (C) 2000 Elsevier Science S.A. A ll rights reserved.