Field-induced electron emission from nanoporous carbons of various types
Influence of fabrication technology on field electron emission properties of nanoporous carbon (NPC) has been investigated. Samples of NPC derived from different carbides via chlorination at different temperatures demonstrated similar low-field emission ability with threshold electric field 2 – 3 V/µm. This property correlated with the presence of nanopores with characteristic size 0.5 – 1.2 nm determining high values of specific surface area (> 800 m2/g) of the material. In most cases, current characteristics of emission were approximately linear in Fowler-Nordheim (FN) coordinates (excluding a low-current part near emission threshold), but the plots’ slope angles were in notable disagreement with known material morphology and electronic properties, unexplainable within the frames of FN emission theory. We suggest that the actual emission mechanism for NPC involves hot electrons generated at internal boundaries, and that emission centres may be associated with relatively large (20 – 100 nm) onion-like particles observed in many microscopy images.