Use of excitons in materials characterization of semiconductor system

The objective of this review article is to provide an overview of the use o f excitons in the characterization of semiconductor alloys and quantum well structures. In particular, it is shown how the measurements of the exciton ic linewidth at low temperatures using a variety of optical spectroscopic t echniques such as photoluminescence (PL), cathodoluminescence (CL), and abs orption can be used to provide information about the structural quality of alloys and quantum well structures. The results of several theoretical appr oaches that have been developed to calculate the excitonic linewidth in sem iconductor alloys as a function of compositional disorder, which is primari ly responsible for excitonic line broadening, are reviewed. The measurement s of the excitonic linewidths in a variety of III-V and II-VI based semicon ductor alloys are described and compared with the calculated values to obta in information about their quality. This is followed by a review of the res ults of a theoretical formalism, which has been used to calculate the excit onic 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 resu lts of the measurements of excitonic linewidth in several m-V and II-V semi conductor based quantum well structures are reviewed and compared with thos e calculated to gain insight into their quality. This article is intended t o provide a balanced review of both the theoretical and experimental develo pments in this field. (C) 2001 Elsevier Science B.V. All rights reserved.