Electron-phonon interaction and current in strong electric fields

Using the Houston-wave approach we investigate the electron-phonon interaction in electric fieldsF which are sufficiently strong to change an electron's Bloch state drastically during the relaxation time τ, but still too weak to support standing electron waves between the band edges. We calculate τ for the low density, high temperature limit and find τ～F ^?1/2. The electric current in the field region of the “hot electrons” between its ohmic rise and its decrease proportional toF ^?1 is determined. Its increase withF ^+1/2 in the limit of relatively low fields agrees with Shockley's result.