Hafnium carbide films and film-coated field emission cathodes

We have previously reported on field emission improvements in turn on voltages and emission stability using ZrC films. However, during our emission studies of bulk carbides, HfC was found to be slightly superior. We now report on work in progress investigating HfC films and HfC film coated field emission cathodes. Uses for arrays of these field emission cathodes range from video displays to microwave applications. This paper deals with physical vapor deposition of HfC, absolute work function measurements, and electron emission properties of these film surfaces. This work demonstrates improvements by using HfC films over films of ZrC and an associated surface work function lowering of more than 1 eV in some instances.