Dielectric instability and breakdown in SiO2 thin films

Dielectric instability and breakdown in SiO2 have been well characterized by many experimental techniques, including measurements of thickness dependence, contact barrier dependence, and time dependence of breakdown as well as a determination of radiation sensitivity and prebreakdown charge buildup within the insulator. All of the various types of data can be explained consistently by an impact ionization model, which predicts a negative‐resistance type of instability; electrons are injected from the cathode, the electron distribution is heated, hot electrons ionize the lattice, and the residual positive charge distorts the electric field and further increases impact ionization. The model is sensitive to two key parameters, the ionization bandgap Ei, and the electron–phonon scattering length λ.