What is the main difference between a silicon diode and a Zener diode?

The main distinction between a silicon diode and a Zener diode is that a Zener diode is specifically designed to operate in reverse bias mode, allowing it to regulate voltage. Silicon diodes generally permit current to flow in one direction and block it in the reverse direction, but they do not have the capability to stabilize or regulate voltage levels. In contrast, Zener diodes are engineered to enter the breakdown region when reverse biased, maintaining a nearly constant output voltage regardless of variations in the input voltage or load conditions.

This characteristic makes Zener diodes extremely useful in applications such as voltage regulation and reference voltage circuitry. They stabilize the voltage in a circuit, providing a reliable power supply for sensitive electronic components. This specialized functionality is not a feature of standard silicon diodes, which are typically employed for rectification purposes rather than voltage regulation.