Abstract Tohoku University announced on October 12, 2016 that it has cooperated with the University of Tokyo to produce an electric double-layer transistor using three-dimensional nanoporous graphene. Graphene is a two-dimensional layer composed of a single layer of carbon atoms, which has excellent transistor performance, but it needs to be stacked at a practical level...
Northeastern University announced on October 12, 2016 that it has cooperated with the University of Tokyo to produce an electric double-layer transistor using three-dimensional nanoporous graphene. Graphene is a two-dimensional layer composed of a single layer of carbon atoms, which has excellent transistor performance, but it needs to stack several thousand sheets to reach a practical level. By using porous three-dimensional graphene to fabricate transistors, the capacitance is up to 1000 times that of two-dimensional graphene transistors.
In order to make maximum use of the surface area of three-dimensional nanoporous graphene, the researchers made nanoporous graphene dried by supercritical CO2 on the premise of not destroying the nanoporous structure, as the conduction path (channel) and function of the transistor. Electrode) electrode. Then, the sample is completely immersed in a liquid (ionic liquid) composed of a cation and an anion which are stable at room temperature, and an electric double layer is formed which applies an electric field between the working electrode and the channel, and the electron concentration of the channel changes. Transistor.
From the behavior of three-dimensional nanoporous graphene transistors, the researchers observed the characteristics of field-effect transistors using Dirac electrons, that is, the conductivity is extremely small, and the conduction carriers are reversed from electron to hole. This indicates that the characteristics of the two-dimensional graphene sheets are well retained. The detected electrostatic capacitance is very high, about 100 to 1000 times that of a planar structural element using a two-dimensional graphene sheet. This shows that highly integrated graphene sheets can be used as a whole to control the electronic state.
Moreover, by theoretically deriving the characteristics of the three-dimensional nanoporous structure, the researchers found that the magnetoresistance effect and the Hall resistance measured under different electron concentration states are represented by one curve. This means that "conducting electrons enclosed on a curved surface has many different orientations for the direction of the applied magnetic field" and is a behavior unique to three-dimensional nanoporous graphene. It shows that the electron mobility of the transistor developed this time is much higher than the required performance, that is, 200cm2/Vs, reaching 5000~7500cm2/Vs.
This study confirmed that a transistor using three-dimensional nanoporous graphene can control the electron density of a highly integrated large-area two-dimensional atomic layer by an electric field by utilizing a nanoporous structure. In the future, progress is expected in the practical use of graphene and molybdenum disulfide, photosensitive elements using atomic layers, and highly integrated three-dimensional circuits. At the same time, new materials are expected to be born in the field of "three-dimensional nanoporous structures" using graphene and other atomic layer materials.
This research has been researched by the Japan Science and Technology Promotion Agency (JST) strategic creation research promotion business CREST "Improvement of energy efficient phase interface science" research field, the Japanese Ministry of Education, the Ministry of Science and Technology, the new academic field research "atomic science", Japan's top world Support from the International Research Center Program (WPI). The research results have been published in the online edition of the German science journal Advanced Materials on October 11, 2016. (Contributing author: Kudo Kudo)
