Linear and Nonlinear Optical Properties of Germanium and Dilute Nitride Containing Semiconductors
The description of the interaction between light and matter is the basis of our understanding of the electro-optical properties of semiconductors. It is of special importance for semiconductor laser systems. The gain medium of these systems is described with the help of a microscopic many-body theor...
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|Zusammenfassung:||The description of the interaction between light and matter is the basis of our understanding of the electro-optical properties of semiconductors. It is of special importance for semiconductor laser systems. The gain medium of these systems is described with the help of a microscopic many-body theory. In this work, such a theory is applied to calculate the photoluminescence of dilute nitride containing semiconductors. Theory-experiment comparisons enable the determination of formerly controversially discussed system parameters of this material class, which represents a promising candidate for more efficient lasers. It is shown that the discontinuity of a GaAs/Ga(NAs) interface is type I. Similarly, a microscopic theory can be applied to calculate the absorption of semiconductors. In this work, the coherent absorption of pump-probe experiments in Ge and (GaIn)As quantum wells is modeled. The experimental findings are reproduced if different dephasing mechanisms are assumed for the samples; a consequence of the different nature of the band gap (direct or indirect). Additionally, the terahertz absorption for indirect semiconductors is modeled. For this purpose, the microscopic many-body theory is extended to include systems with mass anisotropy. On the example of Ge and Si, it is shown that as a result of the mass anisotropy, two distinct resonances appear in the terahertz absorption spectrum.|