On the possibility of wake-field effects in the conductivity of doped semiconductors

Abstract

The formation of a wake field around a swift ion passing through an electron gas and the resulting contribution to the stopping power acting on the ion is an intensively studied phenomenon in metals and semiconductors. The present investigation serves to clarify whether an analogous effect, namely the formation of wake fields and a corresponding contribution to the resistivity, might occur in the Galilei-transformed case of electronic transport in doped semiconductors where the gas of drifting charge carriers passes through an array of fixed impurity ions. By use of an appropriate dynamical screening theory we show that indeed a local plateau in the current density versus field characteristic has to be expected whenever the mean drift energy per carrier exceeds the sum of the mean thermal carrier energy and the zero-point energy of the longitudinal plasma mode of the carrier gas. However, our survey of the published literature suggests that this condition might be too stringent, at least for bulk materials and standard experimental situations, where the strong carrier heating in the high-field regime of relevance in combination with other drift-limiting mechanisms or interband electron-hole avalanching would always precede and prevent the formation of the wake.