Excitonic approach to the ultrafast optical response of semiconductors

Dawei Wang, Margaret Hawton, and Marc M. Dignam
Phys. Rev. B 76, 115311 – Published 12 September 2007

Abstract

We present a theoretical approach to treating the coherent dynamics of optically generated charge carriers in semiconductors using an excitonic basis. In contrast to the semiconductor Bloch equations, our approach treats intraband correlations without factorization. It also includes phase space filling effects that have generally been omitted in previous excitonic treatments of coherent dynamics. We show that, in the coherent limit, where the intraband dephasing time and population decay time are both equal to half of the interband dephasing time, our excitonic approach agrees with the semiconductor Bloch equations to at least third order in the optical field, but that it differs significantly in more general situations. Our excitonic equations are shown to be particularly applicable in systems, such as biased semiconductor superlattices, where bound excitons dominate the optical response and where intraband correlations play a central role. Using a simple model of a nanoring, we show how the spectral shifts in the interband response can be explained in terms of phase-space-filling-induced excitonic population dynamics.

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  • Received 26 June 2007

DOI:https://doi.org/10.1103/PhysRevB.76.115311

©2007 American Physical Society

Authors & Affiliations

Dawei Wang1, Margaret Hawton2, and Marc M. Dignam1

  • 1Department of Physics, Queen’s University, Kingston, Ontario, Canada K7L 3N6
  • 2Department of Physics, Lakehead University, Thunder Bay, Ontario, Canada P7B 5E1

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Issue

Vol. 76, Iss. 11 — 15 September 2007

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