Observation of Hot-Electron Shot Noise in a Metallic Resistor

Abstract

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 mm. 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 ͑ p 3͞4͒2eI. However, further reduction in length below the electron-electron interaction length decreases the noise to a value approaching the independent hot-electron value ͑1͞3͒2eI first predicted for mesoscopic resistors. [S0031-9007(96)00179-2]

Shot noise in mesoscopic conductors

“…Indeed, enhanced (as compared to the 1/3-suppression) shot noise was observed experimentally by Steinbach, Martinis, and Devoret [80]. Their experimental data are shown in Fig.…”

“…The suppression factor in this experiment lies between 0.2 and 0.4 (depending on gate voltage). More precise experiments were performed by Steinbach, Martinis, and Devoret [80] who analyzed silver wires of different length. In the shortest wires examined they found a shot noise slightly larger than 1/3 and explained this larger value as due to electron-electron interaction 20 .…”

“…Expressions (79) and (80) are valid in the linear and non-linear regimes, provided interactions are not important. We will consider the noise in the non-linear regime in Section V, where it will be shown that effects of charging of the well may play an important role.…”

“…The last statement implies the following scenario for noise in metallic diffusive wires [80]. There exist three inelastic lengths, responsible for dephasing (L 1 ), electron heating (L 2 ) and inelastic scattering (L 3 ).…”

Shot noise measurements in graphene

“…4 This heating effect will become less important at large bias because the shot noise will eventually take over fully and, thus, the value of F saturates. Other mechanisms that can change the measured Fano factor include electron-electron interactions [24,5], incoherent scattering [9], and thermal gradients in the metallic lead due to heat diffusion [25]. However, the first two processes should lead to F = 1/3 as V bias → 0 and higher F in the high bias regime (i.e.…”