Real PN Diodes: Generation and Recombination Currents

This lecture discusses the behavior of real PN diodes, focusing on the generation and recombination currents. It begins by contrasting ideal and real PN diodes, emphasizing the importance of considering three distinct regions: the depletion zone and two diffusion zones. The instructor introduces a new model that integrates the net recombination rate across these zones. The lecture details how the diffusion currents of minority carriers dominate under certain conditions, particularly when the voltage is above 0.7V. It also covers the effects of temperature and impurity concentration on breakdown voltage, explaining phenomena such as avalanche breakdown and tunneling effects. The characteristics of Zener diodes and backward diodes are explored, highlighting their unique current-voltage behaviors. The lecture concludes with a discussion on the equivalent circuit for small signals, including differential conductance and junction capacitance, providing a comprehensive understanding of the operational principles of real PN diodes in various conditions.