Tem and eels investigation of a-C and ta-C coated field emitters

摘要

The microstructure of highly sp~2 bonded amorphous carbon and partially tetrahedrally bonded amorphous carbon deposited on needle-shaped molybdenum field emitters by pulsed laser ablation and cathodic arc deposition techniques was studied using transmission electron microscopy and electron energy loss spectroscopy. Undoped and nitrogen-doped films were included in this study. The undoped laser ablation films were approximately 50percent sp~2 at the emitter tip and 65percent sp~2 along the shank, while the N-doped laser ablation films were highly sp~2 bonded both at the tip and along the shank. These laser ablation films were continuous and relatively uniform, exhibiting an isotropic microstructure at the emitter tip and a columnar microstructure along the shank. The cathodic arc deposited films were predominantly sp~2 bonded both at the tip and along the shank; these films were non-uniform, with an isotropic microstructure at the tip and regions of isotropic, columnar, and mixed microstructure appearing along the shank.