Polar Phonon Scattering at the Si-SiO_2 Interface

摘要

In studying fine structures in the tunneling current characteristics of degraded bipolar transistors we have observed under small forward bias a unique spectral pattern of current variations at low temperature. The structures are step-like increases of the base-emitter current that repeat in well-defined voltage sequences. Among these, replicas with a spacing of 135 mV, which is equivalent to the energy of a polar optical phonon in SiO_2, are identified quite often. We believe this is the first evidence of the polar phonon scattering for transport at the Si-SiO_2 interface.