ABSTRACT
Optical studies belong to one of the richest areas of solid-state and semiconductor physics. Characterization techniques utilize a wide range of the electromagnetic spectrum, from radio waves to the ultraviolet. Methods involving photons with higher energies, x-rays and gamma rays are discussed in Chapter 10. Energy absorption and emission processes may involve photons alone, but in many cases, electrons or ions play a role in the interactions. Photoelectron spectroscopy, for example, uses photons to emit electrons out of a semiconductor surface while cathodoluminescence is the process of light emitted from a semiconductor surface upon bombardment with energetic electrons. There are many reasons why photons are exceptionally well suited for semiconductor
defect characterization (Perkowitz, 1993). Photons essentially provide “pure” energy and can be produced monochromatically at high intensities (e.g., lasers, electron synchrotrons) over an extremely wide energy range. Photons can be manipulated easily and sent over large distances. At energies exceeding ~1 eV, single photons can be counted. Photons travel fast and offer the highest time resolution, providing insight into phenomena occurring on femtosecond (10-15 s) time scales. Additional sensitivity can be achieved by modulating a physical parameter, such as stress or magnetic field, and using a lock-in amplifier to measure the corresponding modulation in optical properties. A discussion of all possible techniques involving photons would fill many volumes.
