Gate dielectric materials, polymers used

Common polymers such as polystyrene (PS) and polymethylmethacrylate (PMMA) have been used as gate dielectric materials [7,20,46]. Their ready availability made them some of the early polymers investigated by researchers in the field [11,39,47]. However, the low capacitances of these films made them less attractive than other polymers. Poly(4-methylstyrene) has been explored as a possible polarizable gate insulator [48]. 

Besides the general insulating properties of insulating materials, chemical and thermal stability is required and excellent film-forming properties and methods for patterning the insulating layer. Therefore, the most common polymers (e.g. polyethylene, polypropylene, polyvinylchloride etc.) have not yet been used as gate-dielectric layers. 

It is certain that electrically conductive polymers have attracted much attention in the field of solid state science in recent years. They are expected to have convenient function in the production of useful electric or electronic devices such as the electrodes in rechargeable batteries, pn-junctions for use in integrated circuits (ICs) or in photovoltaic devices, and so on. In the normal sense, the organic polymers, even the 7r-conju-gated systems having mobile 7r electrons, are typical insulators of poor electrical conductivity and have been utilized as dielectric material. This is considered to be a result of the Peierls transition (Peierls, 1955), namely, a metallic-insulator transition, e.g., for polyacetylene, which is characteristic in the one-dimensional system. This situation is circumvented by the doping technique, in which the electron acceptors or donors... 

In 2005, Philips, which invests around 10% of its sales income on research and development, claimed a new research breakthrough with a polymer-based memory which is non-volatile, that is to say it will not lose data when the power supply is switched off. The technology involves the use of a field-effect transistor in which the gate dielectric is composed of a polymer ferro-electric material. Applications include the ability to make low-cost radio-frequency identification tags (RFID), a product which is being widely introduced into logistics and retail businesses with reported world production estimates of some 1.3 billion tags in 2005. 

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