Optical Properties of Disordered Condensed Matter

Koichi Shimakawa, Jai Singh, S. K. O'Leary

    Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review


    This chapter reviews the understanding of the fundamental optical properties in some disordered semiconductors. It presents two approaches that are used for calculating the absorption coefficient in amorphous semiconductors. In the first approach, one assumes that the transition matrix element is independent of the photon energy. In the second approach, contrary to the first one, using the constant dipole approximation, the transition matrix element is found to be photon-energy dependent. Applying the first approach, one obtains the well-known Tauc's relation for the absorption coefficient of amorphous semiconductors. It is shown that, through the first approach, both the fractal and effective medium theories are useful in explaining the optical properties of disordered forms of condensed matter. The chapter also discusses the effect of the compositional variation on the optical gap of amorphous chalcogenide alloys. The bandgap varies with the composition and often exhibits extrema at certain stoichiometric compositions.
    Original languageEnglish
    Title of host publicationOptical Properties of Materials and Their Applications
    EditorsJai Singh
    Place of PublicationNew Jersey
    PublisherJohn Wiley & Sons
    Number of pages16
    ISBN (Electronic)9781119506003
    ISBN (Print)9781119506317
    Publication statusPublished - 2020


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