Scanning Cathodoluminescence Microscopy

CL is a major research tool used in the semiconductor and mineralogy/geology fields. We have reviewed the basic physics necessary to understand CL and discussed some of the conceptual and technical issues involved in the acquisition of CL micrographs or spectra. The overriding concerns in the design, construction, or use of CL hardware is that CL is a weak signal and that every attempt must be made to maximize the collection of emitted photons. Various types of CL experiments exist from which quantitative data can be obtained. The major examples are voltage-resolved, current-resolved, temperature-resolved, and time-resolved CL. Modern advances in instrumentation have led to major improvements in the quality of CL data that is obtainable. Spectral imaging, where an entire spectrum is obtained at each image point, allows rich datasets to be obtained. Pulsed excitation allows time-resolved experiments with high temporal resolution to be performed, and high-performance SEMs and high-efficiency CL hardware allows CL experiments to be performed with near-nanometer spatial resolution. CL is actively used in many different fields of research, but major fields-GaN, ZnO, QDs, PVs, silicon VLSI technology, geology, and organics-were reviewed. Other topics of active CL research involve the use of CL to measure strain and residual stresses in solids and to examine surfaces. CL in the STEM is a powerful, nearly atomic-resolution technique, but it is limited by the complexities associated with STEM-CL instrumentation. In short, CL is a vital technique to the solid-state sciences and will continue to evolve and grow as new hardware is developed, new materials are investigated, and new techniques are applied to established materials. This review was written while the authors were at the Analytical Instrumentation Facility, Department of Materials Science and Engineering, North Carolina State University. We thank the publishers and copyright holders who allowed us to reprint the various figures included in this review.