Diode Behavior: Current Dominance in P+/N- Junctions

This lecture discusses the behavior of current in P+/N- junctions, focusing on the dominance of hole current over electron current in forward bias conditions. The instructor begins by analyzing a P+ diode, which is heavily doped on one side, and a less doped N- side. The key question addressed is whether the current is dominated by electrons or holes when the diode is in forward mode. The instructor explains the energy distribution of holes and electrons at equilibrium and the significance of the built-in potential barrier that both types of charge carriers must overcome. As the doping level of the P side increases, the barrier for electrons becomes larger, leading to a decrease in electron current while the hole current remains dominant. The lecture also covers the IV characteristics of diodes under various doping conditions, including the effects of avalanche breakdown and tunneling in highly doped diodes. The instructor emphasizes the relationship between doping levels and the resulting current behavior in semiconductor devices.