Field Electron Emission from Point Diamond Cathodes under Continuous Laser Irradiation

The results of the study on the impact of continuous visible laser irradiation on the field emission properties of point cathodes which are diamond needle-like microsized crystallites with a nanometer tip radius, are presented. The measurements were conducted in a vacuum diode configuration with a flat metal anode using DC voltage source. An increase in the field emission current was observed when the diamond needle was illuminated by laser radiation. The magnitude of the current changes directly proportional to the power of the radiation. At a maximum power density value of about 400 W/cm(2), the relative increase in current under the action of laser irradiation was 13%. The relative increase in current is determined by the parameters of the dark current-voltage characteristic and reaches its maximum value in the region corresponding to the minimal increase in dark current with voltage. It is shown that the most probable mechanism for the current increase is the change in the electrical resistance of the diamond microneedle as a result of the absorption of laser radiation with the involvement of electronic levels located in the bandgap of diamond, associated with impurities or structural defects in the near surface layer of the diamond microneedle.