Development of Multiple-Valued Logic Level Transistor Using Molecular Wire

Opening the Way to Future Molecular Devices and Molecular Wiring

2008.09.09

National Institute for Materials Science

Dr. Yutaka Wakayama of the Advanced Electronic Materials Center, National Institute for Materials Science and a team headed by Prof. Kenji Kobayashi of the Graduate School of Science and Technology, Shizuoka University succeeded in the development of a multiple-valued logic level transistor using a molecular wire grown by self-assembly.

Abstract

  1. Dr. Yutaka Wakayama of the Advanced Electronic Materials Center, National Institute for Materials Science (President: Teruo Kishi) and a team headed by Prof. Kenji Kobayashi of the Graduate School of Science and Technology, Shizuoka University succeeded in the development of a multiple-valued logic level transistor using a molecular wire grown by self-assembly.
  2. In organic transistors, growth of thin films which combine higher quality crystallinity and large overlap of the π electron orbits has become the key to improved device performance. If development of applications extending to flexible substrates is also considered, the flexibility which is a characteristic of organic materials becomes an essential condition. Previous research has investigated a large number of material systems, such as polymer thin films fabricated by wet processes, organic thin films produced by vacuum processes, and the like. However, no material system and production process which provides all of these features simultaneously had yet been established. Therefore, this research focused on molecular wires as a material system which simultaneously achieves the three necessary conditions of a π conjugated system, a single crystal structure, and flexibility.
  3. The molecule used in this work has a structure in which a substitution group is introduced in a pentacene molecule, resulting in high molecular alignment of the π conjugated system in crystal. When this substance was produced by vapor deposition in a vacuum, it was found that a 1-dimensional wire crystal forms by self-assembly. Furthermore, the substance as a single crystal structure, and measurements of resistivity revealed that its resistivity is one order lower than that of conventional organic semiconductor materials.
  4. A multi-channel transistor structure with multiple parallel junctions of this molecular wires between the source and drain electrodes was fabricated. Independent control of the drain currents in each of the molecular wires was successfully achieved, and as a result, transistor operation which enables switching between multiple-valued logic levels was realized.
  5. A report of this research achievement is to be published on the Nano Letters on-line on September 10, 2008.