Conduction mechanisms and voltage drop during field electron emission from diamond needles

Highlights: • Nanometer-size diamond needles are used in a eld emission experiment and act as point electron sources. • The emission current shows a combination of Poole–Frenkel and Fowler–Nordheim mechanisms. • The voltage drop of the emitted electrons can be predicted and shows a linear dependence with respect to the tip bias. • Laser illumination of the apex of the diamond needle lead to a shift in the voltage drop. -- Abstract: We report results of experimental investigation of field electron emission from diamond nanoemitters. The measurements were performed with single crystal diamond needles fixed at tungsten tips. The voltage drop along diamond needles during emission was revealed and measured using electron energy spectroscopy. The observed linear dependence of the voltage drop in diamond on voltage applied to the tungsten tip is explained in the frame of a simple macroscopic electrical model combining Poole–Frenkel conduction along the diamond tip and Fowler–Nordheim tunneling at the diamond-vacuum junction. Experimental evidences of electron emission sensitivity to laser illumination are discussed for possible modification of diamond emitter characteristics and voltage drop.