Evidence of nonplanar field emission via secondary electron detection in near field emission scanning electron microscopy

摘要

Nonplanar field emission from electrochemically etched tungsten field emitters has been observed using near field emission scanning electron microscopy. Close-proximity field emission in adequate ultrahigh vacuum conditions was implemented to attain Fowler-Nordheim plots using typical imaging parameters. The emission radii deduced via a detailed, spherical surface field emission theory, by [Edgcombe and de Jonge, J. Phys. D 40, 4123 (2007)], reveal that our sharpest tip asperities are less than a nanometer. This yields a spatial resolution on the order of one nanometer.