Theory of p-n junctions

The theory of p-n junctions describes how two types of semiconductor materials—p-type (rich in holes or positive charge carriers) and n-type (rich in electrons or negative charge carriers)—connect to control electric current flow. When joined, electrons from the n-side and holes from the p-side combine, creating a boundary called the depletion zone that acts as an electrical barrier. Under certain conditions, this zone allows current to flow in one direction (forward bias) but not the other (reverse bias), enabling devices like diodes to convert AC to DC. This behavior is fundamental to many electronic components.