Forwardspænding

Forwardspænding, also known as forward bias, is a fundamental concept in semiconductor device physics, particularly for diodes and transistors. It describes the condition where the voltage applied across a semiconductor junction allows current to flow more readily. Specifically, for a p-n junction diode, forwardspænding occurs when the positive terminal of a voltage source is connected to the p-type material and the negative terminal is connected to the n-type material. This applied voltage opposes the built-in potential barrier that normally exists at the junction, effectively reducing its height.

When forwardspænding is applied, majority charge carriers (holes in the p-type material and electrons in the n-type material) are pushed towards the junction. As the applied voltage increases, more carriers have enough energy to overcome the reduced potential barrier and cross the junction. This results in a significant flow of current through the diode, which is known as the forward current. The relationship between forward voltage and forward current is typically exponential. A small increase in forward voltage beyond a certain threshold, known as the forward voltage drop or turn-on voltage, can lead to a large increase in forward current. This behavior is crucial for the operation of diodes as rectifiers and switches.