Intraband Transitions in Quantum Structures

Author: Lazare Diakonidze
Keywords: intraband optical transitions, quantum structures
Annotation:

In this thesis, we investigate intraband optical transitions in quantum structures, specifically in GaAs/AlGaAs quantum wells. Intraband transitions play a significant role in devices such as infrared detectors and lasers. Quantum wells, which confine the movement of electrons and holes, lead to the discretization of the energy spectrum, distinguishing them from bulk crystals. We study intraband optical transitions where electrons and holes transition between discrete energy levels within the conduction or valence band, absorbing or emitting light. The probability of these transitions, determined by the transition dipole matrix element, depends on the overlap of the wave functions. The value of the integral resulting from the overlap of wave functions is directly dependent on the thickness of the quantum well. As the thickness of the quantum well increases, the probability of intraband optical transitions also increases. This is because in a wider well, the overlap of wave functions is more intense, thereby increasing the transition probability. Thus, controlling the thickness of the quantum well is a crucial factor in optimizing intraband optical transitions, which can be applied to the optimization of various infrared detectors and lasers. Therefore, the optimal design and thickness control of the quantum well are essential to achieving high efficiency. For optimizing optical devices, it is evident that changes in the energy range between levels should be considered based on size.