reverse-biased junction

A reverse-biased junction is a fundamental concept in electronics, specifically within semiconductor devices like diodes. It occurs when a voltage is applied across a p-n junction in such a way that it opposes the natural flow of charge carriers.

In a p-n junction, a p-type material (with an excess of holes) meets an n-type material (with an excess of electrons). When a reverse bias is applied, a positive voltage is connected to the n-type side, and a negative voltage to the p-type side. This causes the majority charge carriers (electrons in the n-type and holes in the p-type) to move away from the junction. This creates a region devoid of free charge carriers, known as the depletion layer, which acts as an insulator. Consequently, very little current flows through the junction under reverse bias, except for a small leakage current. This property of allowing current flow in only one direction is called rectification and is crucial for devices like diodes.1234