High mobility states in polymeric dielectrics: A search by internal photoemission

Most models of intrinsic dielectric breakdown are based on a “hot” electron mechanism such as avalanche formations by impact ionization. Surprisingly no direct experimental information about the processes which control hot electron properties in polymeric dielectrics is available. As an example, polyethylene (PE) is considered. PE has a band gap of the order of 10 eV and a breakdown field of the order of 10⁷ V/cm, which requires a mean free path of the order of 100 Å or a mobility of the order of 100 cm²/Vsec for carrier multiplication. This is compatible with the band parameters of PE but at odds with the observed mobilities of 10⁻¹¹ – 10⁻⁴ cm²/Vsec. ⁽¹⁾