A copolymer of vinylidene fluoride and tetrafluoroethylene is solution cast on aphyphen;type silicon wafer. A strong inversion is produced at the silicon surface when the copolymer film is corona charged or when a subsequently evaporated aluminum gate is biased. Although the dipole alignment in the copolymer is stable, the inversion decays. The decay of the inversion layer is monitored by measuring the decay of the surface channel currents between a source and a drain. For the case of corona charging, an initial rapid decay not observed in the gated device is explained by the motion of excess positive charges (dielectric relaxation). The slow decay subsequently observed is explained in terms of the thermionic injection of inversion electrons across an interface barrier and also using a spacehyphen;chargehyphen;limited injection model. Both models fit the results and their validity is discussed.
展开▼
