Field emission of micro aluminum cones coated by nano-tips of amorphous diamond

Nano-tips of amorphous diamond films were deposited on Al micro cones to form a metal/diamond interface structure. The amorphous diamond films were deposited by cathodic arc at a temperature less than 150 °C. The turn on applied field was 4.5 V/μm at 10 μA/cm² for the Al/diamond structure. The turn on applied field is approximately 10 times lower than that for Al alone. The high emission current was obtained (50 mA/cm²) due to metal/diamond structure and the presence of defect band within band gap of amorphous diamond that allowed electrons to pass through with little hindrance. Moreover, the stability of electron emission was monitored at electrical field strength of 7 V/μm for 100 h. The fluctuations of long-term emission current were at ±4% during the entire duration of monitoring. The fluctuation may be due to the absorption and desorption of molecules by the dangling bonds of carbon atoms on surface of nano-tips of amorphous diamond in a vacuum chamber during electron emission. The high stability of electron emission form micro Al cones by nano-tips amorphous diamond coatings was observed.