Electron emission process of phosphorus-doped homoepitaxial diamond films

Abstract

Electron emission is investigated for phosphorous (P)-doped homoepitaxial diamond films grown by microwave plasma chemical vapor deposition. A comparative study of field emission characteristics is performed for P-doped homoepitaxial diamond films with different electrical resistivities and with different cathode metals. A reduction in the turn-on voltage occurs with decreasing electrical resistivity. A variation in the turn-on voltage occurs with cathode metals. It is revealed that the internal electron emission at the diamond/metal contact has an influence on the field emission characteristics. Moreover, field emission characteristics are measured at various spacings between the anode electrode and diamond surface and at various distances from the cathode metal to the diamond surface just below the anode electrode. No significant change of the average electric field strength between the anode electrode and diamond surface is found between P-doped homoepitaxial diamond films with low and high electrical resistivities. It is suggested that space charge limited current is flowing in the diamond film with high resistivity.