Nonequilibrium green's functions and kinetic equations for highly excited semiconductors: II. Application to the study of nonlinear optical and transport properties of the many-exciton system
✍ Scribed by K. Henneberger; G. Manzke; V. May; R. Zimmermann
- Publisher
- Elsevier Science
- Year
- 1986
- Tongue
- English
- Weight
- 829 KB
- Volume
- 138
- Category
- Article
- ISSN
- 0378-4371
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✦ Synopsis
Nonequilibrium Green's function technique is applied to the many-exciton system under the action of an externally driven light field. Starting with Dyson's equation for the nonequilibrium exciton propagator the shift and damping of exciton-levels due to exciton-exciton interaction are calculated in a local approximation with respect to the density of excitons. As a consequence, the Boltzmann equation of excitons contains many-exciton contributions in the diffusion-and driftterm as well as in the collision integral.
The corresponding diffusion equation is derived yielding a diffusion coefficient decreasing with increasing density and a density dependent source term due to the action of the light field.
Numerical calculations are carried out for A,_,-excitons of a CdS platelet considering a two-beam as well as a one-beam experiment.
For the two-beam case we present the density-profile resulting from nonlinear diffusion and the corresponding reflection spectrum around the A,=,-level. For the one-beam case solving the diffusion equation and Maxwell's equations simultaneously an optical bistability just below the Mott-transition is predicted.