Field-induced electron emission from nanoporous carbon of various types

The 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 the threshold electric field strength of 2–3 V/μm. This property correlated with the presence of nanopores with the characteristic size of 0.5–1.2 nm determining high values of specific surface area (more than 800 m2/g) of the material. In most cases, voltage–current characteristics of emission were approximately linear in Fowler–Nordheim (FN) coordinates (excluding the low-current part near the emission threshold), but the plot slope angles were in notable disagreement with the known material morphology and electronic properties, and this could not be explained 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 centers may be associated with relatively large (20–100 nm) onion-like particles observed in many microscopy images.