Contactless electromodulation for the characterization of semiconductor surfaces/interfaces

Modulation spectroscopy (particularly contactless modes) is a major tool for the study and characterization of semiconductor microstructures (quantum wells, superlattices, etc.), surfaces/interfaces (heterojunctions, semiconductor/vacuum, semiconductor/metal, semiconductor/electrolyte) and also for the evaluation of process-induced damage at surfaces/interfaces. In addition, it is also valuable for the characterization of device structures. A particularly useful form of modulation spectroscopy is electromodulation since it often yields the sharpest structure (third-derivative in the case of bulk/thin film material) and is sensitive to surface/interface electric fields. Furthermore, it can be performed in contactless modes [photoreflectance (PR) and contactless electroreflectance (CER)] that require no special mounting of the sample. This talk will discuss some recent applications of PR and CER to the characterization of a number of surfaces/interfaces.