CHANGES IN METALLICITY AND ELECTRONIC-STRUCTURE ACROSS THE SURFACE FERROELECTRIC TRANSITION OF ULTRATHIN CRYSTALLINE POLY(VINYLIDENE FLUORIDE-TRIFLUOROETHYLENE) COPOLYMERS

The surface ferroelectric-paraelectric phase transition in crystalline copolymer films of vinylidene fluoride (70%) with trifluoroethylene ( 30%), at about 20 degrees C, is accompanied by a dramatic change in bo th the electronic structure and metallicity. The temperature-dependent changes in the electronic structure occur primarily in the conduction band. This P(VDF-TrFE 70:30) material is observed to resemble an n-ty pe semiconductor, and the change in electronic structure at the surfac e ferroelectric transition resembles a semiconductor-to-semimetal tran sition.