The Gunn effect occurs in certain compound semiconductors like gallium arsenide when an applied DC voltage exceeds a critical threshold. Instead of a steady current flow, the electrons form domains that travel across the material, generating microwave-frequency oscillations. This negative differential resistance is the operating principle behind Gunn diodes used in radar and microwave transmitters.
Heard on the job
We can exploit the Gunn effect in this GaAs diode to generate a clean 10 gigahertz signal for the local oscillator.