Hot electrons in germanium and Ohm's law

The data of E. J. Ryder on the mobility of electrons in electric fields up to 40,000 volts per cm are analyzed. The mobility decreases many fold due to the influence of scattering by optical modes and due to increases of electron energy. It is estimated that electron “temperatures” as high as 4000°K have been produced in specimens having temperatures of atomic vibration of 300° K. The critical drift velocity above which there are deviations from Ohm's law is about 2.6 × 10⁶ cm/sec. This is three times higher than the elementary theory and on explanation in terms of complex energy surfaces is proposed.