Optical Transitions in Semiconductors

This lecture covers the K-Selection Rule in semiconductors, the importance of direct bandgap semiconductors for optoelectronic devices, and the optical properties of semiconductors in the presence of an electromagnetic field. It also explains the Fermi golden rule for transition probabilities between quantum states and the joint density of states for controlling transitions. The dielectric function, absorption coefficient, and transition rates are discussed, along with the absorption coefficient for direct and indirect bandgap semiconductors. The lecture concludes with the evaluation of photon absorption using Beer-Lambert Law for monolayer and heterostructure cases.