Long-Time Tail of the Autocorrelation Function for Electron Drift in High Electric Fields in Silicon

The velocity autocorrelation φ(t) function is calculated for electrons moving along a high electric field in n-type silicon. For short times t, it varies as exp(-tτ₀), but for times greater than approximately 1.5τ₀, the short-time exponential decay appears to go over to a t^-3/2 decay. This representation covers the initial relaxation, but a second exponential also appears as relaxation to the nonequilibrium steady state occurs.