Chapter 3: Scanning Electron Microscopy

3.1 Introduction

Scanning electron microscopy (SEM) has become one of the most versatile and useful methods for direct imaging, characterization, and studying of solid surfaces. Just a simple partial enumeration of possible modes of the scanning electron microscope operation shows its capabilities:

Secondary, backscattered, and absorb electron imaging and (SEI. BEI. and AEI, correspondingly), magnetic contrast (Type linteraction with secondary electrons, type Ilinteraction with backscattered electrons, type Illpolarization of secondary electrons (SEMPA, scanning electron microscopy with polarization analysis)), X-ray microanalyzer (energy-dispersive spectroscopy (EDS) and wavelength-dispersive spectroscopy (WDS)). X-ray mapping, voltage contrast, electron beam induced current (EBIC) or charge collection microscopy (CCM), cathodoluminescence (CL), scanning deep level transient spectroscopy (SDLTS), electron channeling (ECP). electron backscattered patterns (EBSP) and electron backscattered diffraction (EBSD) with orientation imaging microscopy (OIM), scanning electron-acoustic (thermal wave) microscopy, cryo- or high-temperature microscopy, etc.

Such diversity of applications requires scanning electron microscopes specifically designed for a range of tasks: high-resolution SEM (the surface and topography of solids can be imaged at resolutions approaching 0. 3 nm at 30 keV or 2.5 nm at 1 keV without complex and the time-consuming sample preparation required for TEM observation), X-ray microanalyzer (for chemical analysis of small volumes of materials), variable pressure SEM (allows us to investigate specimens in their natural state or under natural environmental conditions, without the need for conventional preparation techniques), and multi-purpose SEM (an instrument for broad variety of applications), for example.

In this chapter we will describe only modes of the SEM operation. which...