Optical Properties of Semiconductor Superlattices
Semiconductor quantum wells and superlattices1 have received growing interest in recent years. Optical measurements including photoabsorption, photoluminescence, and Raman scattering are widely adopted for probing the electronic states of these heterostructures. Using a simple quantum mechanical model which contains essentially a particle in a one-dimensional square-well potential (particle-in-a-box model)2, one can obtain a fairly accurate description of the energy levels in a GaAs-AlxGa1−xAs quantum well with well size between 50 Å and 300 Å. This model predicts a selection rule for the inter-band optical transitions which requires the difference in principal quantum numbers of the initial hole state and the final electron state in a quantum well to be zero, i.e. Δn = 0. Indeed, most experimental data indicate that Δn = 0 transitions are at least an order of magnitude stronger than the other transitions which violate this selection rule.
KeywordsOscillator Strength Excitonic State Envelope Function Excitonic Transition Barrier Width
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