Abstract
In a Scanning Field-Emission Microscope (SFEM) [1-3] originating from the topografiner technology [4], the tip-surface distance is few nanometers to few tens of nanometers and the electrons impinging on the target are field emitted from the tip. Accordingly, SFEM is not only capable to map the surface micro-topography - as done in conventional Scanning Tunnelling Microscopy – but electrons can escape the tip-surface junction and their intensity detected as a function of the surface position (imaging mode). The SFEM operates at very low primary energies (≤100eV) [5], so that the fundamental mechanisms relevant for the generation and emission of Low-Energy Secondary Electrons are poorly understood. Energy analysis of these electrons would provide useful information, essential e.g. for understanding the origin of contrast in imaging. However, such an energy analysis is made technically difficult by the presence of extremely strong ambient electric fields at the site of origin of the electrons. To overcome this limitation, we have designed and implemented a prototype miniature energy analyser, employing a Bessel Box (BB) [6] technology. The compact design of such a BB, mountable in direct proximity of the tip-surface region, could provide a decisive help toward refining the energy analysis of these Low-Energy Secondary Electrons and toward shedding light on the tangled phenomenon of secondary electron emission. Energy enhanced electron detection in SFEM could lead not only to a novel miniaturized spectro-microscopy device but also provide information about fundamental mechanisms of low energy electron scattering and secondary electron production
