Hot-electron noise in two-valley semiconductors: An analytic model

We present results for the hot-electron noise in two-valley semiconductors, such as GaAs, where intervalley transfer plays an important role. The noise is calculated by a Boltzmann--Green-function method. We obtain an analytic solution for a model with two valleys and three relaxation times. Using the measured low-field mobility, lower-valley mass, and valley separation energy {Δ}, while adjusting three upper-valley parameters, we obtain good agreement with both experimental time-of-flight measurements and microwave noise measurements. We find that the hot-electron noise is very sensitive to the transport parameters, much more so than the velocity-field curve. In particular, the noise is very sensitive to the {Γ}-to-L scattering rate and our results indicate that experimental noise measurements might be used for determining this parameter.