Electrochemical Fabrication of Metal/Oxide/Conducting Polymer Junction

Abstract

The electrochemical fabrication of a hybrid inorganic-organic field effect transistor ͑IOFET͒ is described. Ti-Zr mixed oxide ͑dielectric permittivity ϳ45͒ grown by anodizing has been used as a dielectric, while 3,4-polyethylenedioxythiophene has been employed as a semiconducting polymer. The polymerization of 3,4-ethylenedioxythiophene on the oxide has been realized by a photoelectrochemical process. The metal/oxide/polymer junctions have been investigated by photocurrent spectroscopy and scanning electron microscopy. The output transistor characteristics have been recorded in order to test the performance of the junctions in the IOFET structure.After discovery of conducting polymers and the possibility to modify their electrical properties ͑from insulating to metallic like behavior͒ by doping and a careful choice of the processing conditions, a large amount of research effort has been devoted to the theoretical understanding of their solid state properties as well as to exploit the possible application of conducting polymers in many technological fields including large area organic electronics, polymer photovoltaic cell, and sensors. 1-4 Organic thin film transistors appear very promising devices for the development of low cost, flexible, and disposable plastic electronics. In order to reduce the operating voltage it has been suggested in the literature to use mixed inorganic-organic thin film transistors by assembling a structure formed by metal ͑bottom contact͒/dielectric layer ͑gate͒/organic semiconductor/top contact ͑source/drain͒. According to this, a wet electrochemical route appears to be very promising in terms of cost, at least for the preparation of thin ͑thickness Ͻ10 nm͒ or thick ͑thickness Ͼ10 nm͒ oxide films by anodizing in aqueous electrolytes. Moreover, by taking into account the possibility to grow semiconducting polymers on wide bandgap dielectric oxide ͑Ta 2 O 5 ͒ by a photoelectrochemical route, which has been shown recently, 5,6 it seems very appealing to exploit an integral electrochemical route to fabricate advanced inorganic/organic hybrid structure which could be used as a building block for a field effect transistor ͑FET͒ junction.In this paper, we describe and discuss the electrochemical fabrication of a hybrid structure to be used in the production of an inorganic-organic field effect transistor ͑IOFET͒ using 3,4-polyethylenedioxythiophene ͑PEDOT͒ as a semiconducting polymer and anodic films grown on the Ti-10 atom % Zr alloy as dielectrics. The choice of the oxide is based on its low dark current value and quite high photocurrent intensity, under monochromatic light, at not too high anodic potential and photon energy, 7 as well as on its high dielectric permittivity ͑ϳ45, according to Ref. 8͒. The metal/oxide/ polymer junctions are investigated by photocurrent spectroscopy ͑PCS͒ and scanning electron microscopy ͑SEM͒. Finally, output transistor characteristics are recorded in order to test the performance of the junctions in the IOFET structure. ExperimentalTi-10 atom % Zr alloys we...

Critical Review—Photocurrent Spectroscopy in Corrosion and Passivity Studies: A Critical Assessment of the Use of Band Gap Value to Estimate the Oxide Film Composition

“…This is reported in Figures 1-3 for d,d-metals mixed oxides, where the measured optical band gaps as a function of the alloys composition are reported for passive films grown on Ti-Zr and Ta-Nb alloys as well as for physically deposited (Gd x Y (1-x) ) 2 O 3 . [30][31][32][33][34] The amorphous nature of the passive film on Nb-Ta alloys and the absence of any indirectto-direct optical transition crossover in the case of crystalline films grown on Ti-Zr alloys, allowed testing of the suggestion of Zunger and coworkers 25,26 for the regular semiconducting alloys reported above. Figures 1 and 2 show the dependence of experimental E g values of thin anodic passive films vs alloys composition for Ti-Zr and Ta-Nb mixed oxides.…”

Synthesis, characterization, and properties of new conducting polyaniline/copper sulfide nanocomposites

“…Metal nanoparticles with different sizes and shapes can be mixed with conducting polymer to form composite materials, which represent a new class of materials that may combine desirable physical characteristics of both organic and metallic component with single composition. The metallic portion offers the electrical properties, whereas the polymer part can provide thermal stability and mechanical properties to the fabricated polymer . Fabrication of polyaniline (PANI) composite with various materials has received great attention because of their unique properties and applications in various electrical devices .…”

Light induced electropolymerization of poly(3,4-ethylenedioxythiophene) on niobium oxide

“…To overcome the difficulty of performing such electrochemical process on dielectrics, we recently proposed a photoelectrochemical method [4] to grow polypyrrole on tantalum oxide. Such method has been successfully employed to synthesize PEDOT on Ta 2 O 5 [3] and on Ti-Zr mixed oxides [5].…”