Editing Gunn diode (section)

==History==
[[File:ERC Gunn Effect Experiment - GPN-2003-00050.jpg|thumb|[[NASA]] ERC scientist [[W. Deter Straub]] conducting an experiment with the Gunn effect.]]

The Gunn diode is based on the Gunn effect, and both are named for physicist [[J. B. Gunn]]. At [[IBM]] in 1962, he discovered the effect because he refused to accept inconsistent experimental results in gallium arsenide as "noise", and determined the cause. Alan Chynoweth of [[Bell Telephone Laboratories]] showed in June 1965 that only a transferred-electron mechanism could explain the experimental results.<ref name=IEEE_noise>{{cite journal
  | author=John Voelcker
  | year=1989
  | title=The Gunn effect: puzzling over noise
  | journal=[[IEEE Spectrum]]
  |issn=0018-9235}}
</ref> It was realized that the oscillations he detected were explained by the [[Ridley–Watkins–Hilsum theory]], named for British physicists [[Brian Ridley]], Tom Watkins and [[Cyril Hilsum]] who in scientific papers in 1961 showed that bulk semiconductors could display ''[[negative resistance]]'', meaning that increasing the applied voltage causes the current to ''decrease''.

The Gunn effect and its relation to the Watkins–Ridley–Hilsum effect entered electronics literature in the early 1970s, e.g., in books on transferred electron devices<ref>P. J. Bulman, G. S. Hobson and B. C. Taylor. ''Transferred electron devices'', Academic Press, New York, 1972</ref> and, more recently, on nonlinear wave methods for charge transport.<ref>Luis L. Bonilla and Stephen W. Teitsworth, ''Nonlinear Wave Methods for Charge Transport'', Wiley-VCH, 2010.</ref>

[[File:Ganna gjenerators M31102-1.jpg|thumb|upright=0.8|Russian Gunn diode oscillator. The diode is mounted inside the [[microwave cavity|cavity]] ''(metal box)'', which functions as a resonator to determine the frequency. The negative resistance of the diode excites microwave oscillations in the cavity which radiate out the rectangular hole into a [[waveguide]] ''(not shown)''. The frequency can be adjusted by changing the size of the cavity using the slot head screw.]]