  We give a theoretical interpretation of the noise properties of Schottky
barrier diodes based on the role played by the long range Coulomb interaction.
We show that at low bias Schottky diodes display shot noise because the
presence of the depletion layer makes negligible the effects of the Coulomb
interaction on the current fluctuations. When the device passes from barrier to
flat band conditions, the Coulomb interaction becomes active, thus introducing
correlation between different current fluctuations. Therefore, the cross-over
between shot and thermal noise represents the suppression due to long range
Coulomb interaction of the otherwise full shot-noise. Similar ideas can be used
to interpret the noise properties of others semiconductor devices.
