Direct optical thermometry in semiconductors

This pedagogical review offers an easy access to three direct optical methods (photoluminescence, absorption, and Raman spectroscopies) to probe temperatures in out-of-equilibrium semiconductor devices. For each technique, starting from basic considerations, the operating principles and usual assumptions are clarified; the strategy to acquire and analyze data is explained, and the most critical points of attention are underlined with examples. Decision trees and a comparison table are provided to help identify the best suited approach to specific characterization needs.