Use of excitons in materials characterization of semiconductor systems

The objective of this review article is to provide an overview of the use of excitons in the characterization of semiconductor alloys and quantum well structures. In particular it is shown how the measurements of the excitonic linewidth at low temperatures using a variety of optical spectroscopic techniques such as photoluminescence, cathodoluminescence, and absorption can be used to provide information about the structural quality of alloys and quantum well structures. The results of several theoretical approaches that have been developed to calculate the excitonic linewidth in semiconductor alloys as a function of compositional disorder, which is primarily responsible for excitonic line broadening, are reviewed. The measurements of the excitonic linewidths in a variety of III–V and II–VI based semiconductor alloys are described and compared with the calculated values to obtain information about their quality. This is followed by a review of the results of a theoretical formalism, which has been used to calculate the excitonic linewidth due to interfacial disorder in quantum well structures. The combined effects of both the compositional and the interfacial disorders on the excitonic linewidth in quantum well structures are discussed. The results of the measurements of excitonic linewidth in several III–V and II–V semiconductor based quantum well structures are reviewed and compared with those calculated to gain insight into their quality. This article is intended to provide a balanced review of both the theoretical and experimental developments in this field.