Diodes: One-Way Electronic Devices
The diode as a practical junction
What a diode does
A diode is a device built from a p-n junction that strongly prefers current in one direction. It is one of the simplest and most important semiconductor devices.
Forward bias in a diode
In forward bias, the barrier at the junction becomes smaller. This allows many charge carriers to cross the junction, so current increases rapidly.
Reverse bias in a diode
In reverse bias, the barrier becomes larger. Only a very small leakage current flows, so the diode behaves almost like an open switch.
Simple diode behavior
| Bias condition | Barrier | Current |
|---|---|---|
| Forward bias | Lower | Large |
| Reverse bias | Higher | Very small |
What is the main behavior of a diode?
A diode is designed to conduct much more easily in one direction than the other.
Correct answer: It allows current mostly in one direction
What happens to diode current in reverse bias?
Reverse bias greatly suppresses current flow.
Correct answer: it becomes very small
Which device is commonly built from a p-n junction?
A diode is the classic device based on a p-n junction.
Correct answer: Diode
Diode states
Forward biased diode
- Lower barrier
- Current flows easily
Reverse biased diode
- Higher barrier
- Current is strongly reduced