Thermally activated conduction mechanisms in Silicon Nitride MIS structures

This publication reports on thermally activated currents in n-silicon/Si3N4/Al structures. The samples prepared were examined by means of I–V, C–V, ac conductivity and thermally stimulated depolarisation current (TSDC) measurements. The results indicate that DC conductivity is controlled by charge diffusion. Both conductivity and TSDC measurements indicate that mobile carriers which are trapped at the Si/nitride interface for low temperatures are de-trapped when temperature approaches room temperature resulting in a fast increase of DC conductivity. Additionally it is found that at high temperatures the ac conductivity follows a power law with respect to frequency where the exponent is close to two. Implications of this type of variation are also discussed. The results were used in order to explain the contribution of defects to the conduction mechanisms and the device behaviour.