Non−Ohmic electron conduction in silicon surface inversion layers at low temperatures

Abstract

Deviations from Ohm’s law for electron conductivity in silicon surface inversion layers were observed from 4.2 to 20 K using MOS transistors with different amounts of oxide charges. The measurements were compared with a two−dimensional theory of hot electrons in inversion layers. It was found that above 6 K this theory can well account for the observed non−Ohmic behavior. From a comparison of the theory with experimental results the deformation potential constant Z_A for scattering of electrons by acoustic phonons is found to be Z_A=7.8±2.3 eV. The hot−electron theory is in apparent disagreement with the experimental results at temperatures below 6 K, which is discussed. At high drain voltages the samples with the largest amount of oxide charges showed a negative differential resistance.