Screening of the Electron-Phonon Interaction in Semiconductors

Abstract

We calculate the screening of the electron-phonon interaction by free carriers in a semiconductor in two cases: heavily doped semiconductors and intrinsic semiconductors containing a dense electron-hole plasma. For heavily doped semiconductors, the formula includes the bare deformation potential, the electron-impurity Coulomb interaction and the free-carrier screening length. We show how the effective deformation potential goes from the pure semiconductor value to a metallike value at high impurity density. In the case of an electron-hole plasma, the expression is quite different as electrons and holes are both mobile and screen independently the variations of the conduction and valence band extrema.