Field emission properties of the polycrystalline diamond-coated silicon emitters

Abstract

This work examines the electron emission characteristics of a polycrystalline diamond-coated silicon field emitter fabricated by hot filament chemical vapor deposition. The electron emission behavior of a polycrystalline diamond-coated Si field emission array (D/Si-FEA) was compared with that of an uncoated Si field emission array (Si-FEA) and flat-diamond film coated on Si substrate (flat-D/Si). From Raman spectrum and x-ray diffraction pattern analyses, it was revealed that the overcoated diamond film involved structural defects, graphite inclusion, grain boundaries, and a negative electron affinity surface. The direct current current–voltage (I–V) characteristics exhibited linear ohmic emission behavior at low anode voltages and Fowler–Nordheim emission behavior at high anode voltages. The threshold voltages for the D/Si-FEA, Si-FEA, and flat-D/Si were about 250, 666, and 800 V, respectively. The maximum emission current for the D/Si-FEA, 0.23 mA, was obtained for a 500 V anode bias. The low onset voltage of the D/Si-FEA was attributed to the cone-shaped emitter and the excellent properties of the overcoated diamond film.