Nanoscale characterization of an electron emitting tip by scanning probe microscopy

Abstract

Field emission microscopy is commonly used to observe patterns and intensities of electron emissions and to estimate the average work function from the emission current with respect to the applied voltage (F-N plots). However, it is difficult to observe the nanostructure at the apex of the tip using only field emission microscopy. In this research, we investigated the possibility of characterizing the surface of an electron emitter using scanning probe microscopy (SPM). Adding an optical microscope and a light source to the front side of the SPM system, we succeeded in precisely confirming the relative positions of an SPM cantilever and an electron emitter and in observing the surface structure at the top of an electron emitter in a 5 × 5 μ2 region. SPM and scanning electron microscopy images were compared, and both showed grains and their boundaries. Higher magnification SPM images showed flat and concentric circular ring-shaped planes.