Fabrication of low voltage gated microtip arrays with low work function Cu-Li alloy or amorphous diamond coatings and comparison of field emission properties

We have developed a method to produce gated Cu-Li alloy-coated emitter tip arrays that produce device-compatible electron emission at voltages in the range 20-30 V. The technique involves selective deposition of Cu-Li alloy coatings on field emitter tips, using a collimated magnetron sputter deposition process. In this method, the component of the sputter flux normal to the surface of the substrate is preferentially selected from the cosine-distributed sputtered flux from the target by passing this flux through a physical collimator. This collimated sputter deposition method results in a selective growth of Cu-Li on the Si tip, as demonstrated by EDX analysis. The selective Cu-Li deposition results in field emitter tips electrically isolated from the gate with good I vs. V and Fowler-Nordheim behavior. We can also produce low voltage gated field emitter tip arrays coated with amorphous diamond, using the same collimated sputter deposition technique described above. Comparisons of the emission properties between the amorphous diamond and Cu-Li-coated field emitters is presented.