Introduction to EELS

Abstract In this work, we aim to examine structures of interest in the semiconductor materials field that demand characterization solutions at the higher resolution available. The examined semiconductor materials are based on silicon or III–V nitrides, among the more important of their kind for industrial applications. The analyzed samples contain structures, from thin deposited layers to quantum well and dot structures, in the nanometer size range. Our tool of choice, the aberration-corrected and beam-monochromated scanning transmission electron microscope (STEM), gives us the opportunity to push the resolution barrier close to the atomic level. Our aim is to explore the analytical capabilities of the electron energy-loss spectroscopy (EELS) technique in these interesting materials and using the most advanced tools. The following sections in this chapter give an overview of the theoretical foundations of the EELS technique. The low-loss part of the EEL spectrum will be our main analysis tool, so a special focus is put on its main features; the link of the spectral features with theoretical properties of materials and the limitations of the technique. The following chapter describes the analytical and theoretical methods that are used to treat the experimental data and to simulate spectral shapes. After that several separate contributions present results obtained using these tools. Simulation results are first presented in the third chapter, and after that, several more chapters deal with different experimental works. These chapters serve to introduce the more specific techniques that have been developed for the preparation of this research work. These results are aimed at the better understanding of the EELS spectrum, overcoming some of the limitations of the technique, and revealing some interesting properties of the examined materials and structures.