Electron Yield Measurements of Multilayer Conductive Materials

The electron yield (EY), defined as the number of electrons emitted over electrons incident from a sample undergoing energetic electron bombardment, provides a fundamental way to study the interaction of incident electrons with constituent electrons in a material. Electron emission from even simple layered materials with thicknesses on the order of electron penetration depths is a complex problem involving electron transport, electron-electron interactions, and energy transfer processes. To understand how the EY is affected by thin layer structures, SEY, BSEY, and electron emission spectra were measured for two multilayer sample sets. The first sample set had highly ordered pyrolytic graphite substrates with gold sputtered coatings ranging from 1 nm to 100 nm thick. The second sample set had high purity gold substrates with graphitic amorphous carbon foils ranging from 0.5 nm to 500 nm adhered to the surface. The measured yield curves were complex functions of incident energy and coating thickness. The models proposed here necessitate the consideration of the origins of emitted electrons, the nature of elastic and inelastic collisions, and the energy dependent range of electrons.