Unified theory of optical absorption and luminescence including both direct and phonon-assisted processes
Sabyasachi Tiwari, Emmanouil Kioupakis, J. Menéndez, Feliciano Giustino
Abstract
Here, the authors make a fundamental theoretical advancement by unifying the theory of optical transitions in semiconductors including direct and phonon-assisted processes. This unification overcomes the fundamental limitation in the textbook theory of phonon-assisted optical absorption that gives unphysical absorption rates for photon energies greater than the direct band gap. They demonstrate the predictive power of their theory by calculating optical absorption and luminescence in standard semiconductors, and they achieve excellent quantitative agreement with the best available experiments. This work brings a paradigm shift in the theory of optical transitions, and opens the pathway for precise calculations of semiconductor optical properties.