The wake potential and energy loss of a swift ion moving parallel to a heavily doped semiconductor surface in vacuum are studied with the specular-reflection model and the dielectric response theory. The phonon-electron coupling effect on the surface wake potential and the energy loss is investigated by using a frequency-dependent dielectric function. We find that there are two branches of phonon-electron coupling excitations which contribute to the wake potential and the energy loss. Numerical results show that the oscillation form of the wake potential is obviously influenced by the phonon-electron coupling effect.