In Sec. II of this work, we briefly recall the various ways of defining the diffusion coefficientDand discuss their identity in high‐field conditions and in very high frequency operations. In Sec. III, theoretical values obtained by the Monte Carlo method for high static field operations in Si and GaAs are reported and discussed. In Sec. IV, the variations of diffusion values with the operational frequency or with the ’’observation’’ or sample time are studied and tentatively explained.