Fabrication and characterization of a solid-state ambipolar ionic field-effect transistor

Abstract

Transistors are a fundamental building block of the integrated circuit. While standard transistors are based on electron (n-type) or hole (p-type) majority carrier modulation, a new type of transistor known as the ionic field-effect transistor (IFET) has recently been developed that modulates ionic current through an ion-conducting channel when a voltage is applied to a gating electrode. In this thesis work, standard lithography and etching techniques are used to develop the first ever solid-state IC compatible IFET device. Using this approach, large scale arrays of multiple transistor geometries are simultaneously realized for the first time on a single silicon wafer. The active channel layer for the devices is made from the proton-conducting material Nafion[RTM], and the contacts are a proton-transparent Pd/Ag alloy. The elegant design of this state-of-the-art ionic transistor allows it to operate in conditions unsuitable for standard microelectronics, such as aqueous environments. The design also provides an excellent test structure to characterize ionic thin films. As a unique feature, the transistors exhibit an ambipolar response, exhibiting either n-type or p-type behavior, depending on the polarity of the applied gate voltage.