Elucidation of field emission characteristics of phosphorus-doped diamond films

There is much interest in studies on field emission of diamond films because diamond has not only superior properties such as chemical inertness and mechanical hardness but also negative electron affinity (NEA) on the surface terminated with hydrogen atoms. However, the mechanism of electron emission from diamond films has not been clear yet. Therefore, it is necessary to understand it. Phosphorus (P) is one of the most promising candidates as a donor impurity in order to synthesize low-resistive n-type diamond films. Theoretical and experimental P donor levels are 0.2 and 0.43 eV, respectively, from the conduction band edge of diamond films. It is expected that the Fermi level moves toward the conduction band edge by P doping and also that the electric field at the P-doped diamond/metal contacts is enhanced because of forming the space charge layer due to ionized donors.