Observation of hot-electron shot noise in a metallic resistor

We have measured the current noise of silver thin-film resistors as a function of current and temperature and for resistor lengths of 7000, 100, 30, and 1 mu m. As the resistor becomes shorter than the electron-phonon interaction length, the current noise for large current increases from a nearly current independent value to the interacting hot-electron value (root 3/4)2eI. However, further reduction in length below the electron-electron interaction length decreases the noise to a value approaching the independent hot-electron value (1/3)2eI first predicted for mesoscopic resistors.