The effect of interelectrode spacing on field emission in nanodiamond lateral vacuum devices

Nitrogen-incorporated nanocrystalline diamond, offering a high field enhancement factor ( β), has been applied in the development of monolithic lateral emitter diodes. The dependence of the emission current on the interelectrode spacing in the device structure has been investigated. Three batch-fabricated devices, incorporating a 125-fingered nanodiamond lateral emitter array, with different interelectrode spacings of 4 μm, 7 μm and 10.5 μm defined by lithography, were characterized for field emission. The effect of changing the anode–cathode gap was observed in the I– V characteristics, with a distinct reduction in the device turn-on and operating voltages with a decrease in the gap, inversely altering the electric field at the emitter fingers. The nanodiamond emitter devices demonstrate the same low turn-on electric field ( E) of ∼ 2 V/μm and closely matched I– E characteristics. The scaling behavior of the emission current with the interelectrode spacing can be studied at a given applied electric field. For example, at ∼ 8 V/μm, which corresponds to anode voltages of 85 V, 55 V, and 30 V for the 10.5 μm, 7 μm and 4 μm lateral gap devices respectively, the extracted emission current is 5.1 μA. A strong sensitivity of 10 V µm − 1 observed in the field emission behavior of the nanodiamond lateral device as a function of the cathode-anode distance can be utilized in the development of novel sensors and NEMS, reliably operable in harsh environments of temperature and radiation.