A scanning electron microscope (SEM) scans a focused electron beam over a surface to create an image. The electrons in the beam interact with the sample, producing various signals that can be used to obtain information about the surface topography and composition.
Profilometry is a technique used to extract topographical data from a surface. This can be a single point, a line scan or even a full three-dimensional scan. The purpose of profilometry is to get surface morphology, step heights and surface roughness. This can be done using a physical probe or by using light.
The scanning tunneling microscope (STM) works by scanning a very sharp metal wire tip over a surface. By bringing the tip very close to the surface, and by applying an electrical voltage to the tip or sample, we can image the surface at an extremely small scale – down to resolving individual atoms.
Cathodoluminescence (CL) is used to characterize optical properties at the nanoscale. Cathodoluminescence techniques analyze the resulting photons that are emitted in the ultraviolet to near-infrared region of the electromagnetic spectrum.