Working principles of diodes from "summary" of Electronics - Circuits and Systems by Owen Bishop
The working principles of diodes are fundamental to understanding their function in electronic circuits. A diode is a two-terminal electronic component that allows current to flow in one direction while blocking it in the opposite direction. This behavior is a result of the diode's asymmetric structure, which consists of a P-type semiconductor material and an N-type semiconductor material. When a voltage is applied across a diode in the forward bias direction (positive voltage on the P-type material and negative voltage on the N-type material), the diode conducts current easily due to the majority carriers in each semiconductor region. In the P-type material, majority carriers are holes, while in the N-type material, they are electrons. These carriers flow towards the junction between the two regions, where they recombine and allow current to pass through the diode. Conversely, when a voltage is applied in the reverse bias direction (positive voltage on the N-type material and negative voltage on the P-type material), the diode blocks current flow. In this situation, the majority carriers are pushed away from the junction, creating a depletion region where no current can pass. Only a very small leakage current flows in this reverse bias condition, which is typically negligible for most applications. The behavior of diodes can be described by the exponential relationship between current and voltage known as the diode equation. This equation shows that the current through a diode increases exponentially with voltage in the forward bias region, while it remains nearly constant in the reverse bias region.- The working principles of diodes are essential for understanding how these components are used in rectifiers, voltage regulators, signal demodulators, and many other electronic circuits. By controlling the flow of current in a circuit, diodes play a critical role in the operation of electronic devices and systems.
