The electronic properties of the metal-insulator contact: Space-charge induced switching

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Abstract
Reversible changes (switching) in the magnitude of the leakage current through a metal-insulator-metal (semiconductor) structure can be induced by the excitation of electron-hole pairs in the insulator. The switching behavior in metal-polyethyleneterephthalate (PET) metal capacitors is given as a function of the variables: excitation rate, applied electric field, film thickness, and metal work function. The switching is interpreted by a simple model which requires knowledge of the bulk transport of electrons and holes in the insulator, and a high density of hole (or electron) traps near the contact only. The switching occurs when the trapped space charge induces injection from the contact, and saturation is achieved by recombination of the injected carriers with the trapped carriers. Both the time dependence and magnitude of switching is predicted for published switching data in MOS devices with good agreement. Since the model requires knowledge of the current-voltage characteristic for the contact in question, new data for leakage currents in PET is given, with a discussion of the nonfit of the data to the standard injection theories. A fit of the model to the PET switching data is given and the first measurement of the magnitude and field dependence of the recombination coefficient is presented.