Generation and Recombination in Semiconductors

This lecture discusses the behavior of semiconductors out of equilibrium, focusing on generation and recombination processes. It begins with a review of equilibrium equations, highlighting the three unknowns: electric field, free electron concentration, and hole concentration. The instructor explains that these equations, including Maxwell's equation and current equations, are not valid when the system is out of equilibrium. An example of weak injection is presented, illustrating how illumination affects electron and hole concentrations. The lecture then delves into thermal generation and recombination, detailing direct and indirect effects, including band-to-band transitions and trap-assisted processes. The net thermal recombination rate is analyzed, emphasizing the differences between equilibrium and non-equilibrium states. The discussion extends to specific generation and recombination processes, such as optical effects and avalanche phenomena. The instructor concludes by indicating that the next video will introduce these rates into the continuity equation, providing a comprehensive understanding of semiconductor dynamics under varying conditions.