Educational and Working History

Research Interests

Multi-functional single-electron devices with unique molecular dots

Molecular electronic devices such as single molecular transistors and memories have been promising candidates for realizing "beyond CMOS" devices. However, the development of such molecular devices is still at the basic research stage and practical application remains a long way off. The main obstacle is the lack of effective device structures for molecular devices. Device configurations based on nano-gap electrodes and scanning probe techniques have poor compatibility with current CMOS technology. My interest is to develop realistic molecular devices by fusion of attractive molecular functionalities and current Si-technology. For this purpose, I have proposed a multi-functional single-electron memory with functional molecular dots. Organic molecules as quantum dots have many advantages over their inorganic counterparts including size uniformity on a nanometer scale, excellent energy level tunability, and superior photosensitivity. These unique functionalities would achieve novel device operations those are unobtainable in inorganic quantum dots. Our proposed device has enormous potential for realizing a breakthrough in Si-based technology.

Organic filed-effect transistor with specific functionality

Organic electronic devices have attracted considerable attention for realizing printable and flexible logic circuits. In the last decade, great progress has been made as regards the performance of organic field-effect transistors (OFETs). The development of novel OFETs with specific functionality is attracting attention with a view to providing a new direction for organic electronics. Light-emitting OFETs, phototransistors and OFET-based sensors are representative examples of such attempts. Against this background, we propose an external trigger as an alternative to bias gate voltage, namely a photo-field effect transistor with photochromic channel layers. This approach offers attractive new prospects for realizing unique organic devices such as synapse-like organic circuits and human-eye-like sensors.

Selected Papers

1. Single-electron Tunneling through Molecular Quantum Dots in a Metal-insulator- Semiconductor Structure
   R. Hayakawa, N. Hiroshiba, T. Chikyow, and Y. Wakayama

   Adv. Funct. Mater. 2011; 21: 2933-2937.

2. Structural analysis and electrical properties of pure Ge₃N₄ dielectric layers formed by an atmospheric-pressure nitrogen plasma
   R. Hayakawa, M. Yoshida, K. Ide, Y. Yamashita, H. Yoshikawa, K. Kobayashi, S. Kunugi, T. Uehara, and N. Fujimura

   J. Appl. Phys. vol. 110 pp.064103-1-064103-5 (2011).

3. Strain-effect for Controlled Growth Mode and Well-ordered Structure of Quaterrylene Thin Films
   R. Hayakawa, A. Turak, X. N. Zhang, N. Hiroshiba, H. Dosch, T. Chikyow, and Y. Wakayama

   J. Chem. Phys., 2010; 133:034706.

4. Stress Release Drives Growth Transition of Quaterrylene Thin Films on SiO₂ surfaces
   R. Hayakawa, X. N. Zhang, M. Petit, H. Dosch, T. Chikyow, and Y.Wakayama

   J. Phys. Chem. C, 2009; 113: 2197-2199.

5. Interface Engineering for Molecular Alignment and Device Performance of Quaterrylene Thin Films
   R. Hayakawa, M. Petit, T. Chikyow, and Y. Wakayama

   Appl. Phys. Lett., 2008; 93: 153301.

6. Self-assembled molecular nanowires of 6,13-bis(methylthio)Pentacene: growth, electrical properties and applications
   Y. Wakayama, R. Hayakawa, T. Chikyow, M. Shinichi, N. Tomonobu, S. Egger, D. G. de Oteyza, H. Dosch, and K. Kobayashi

   Nano Lett., 2008; 8: 3273-3277.

7. Analysis of Carrier Transport in Quaterrylene Thin Film Transistors Using ultra-slow Vacuum Deposition
   R. Hayakawa, M. Petit, Y. Wakayama,and T. Chikyow

   J. Appl. Phys., 2008; 104:024506.

8. Evolution of Quaterrylene Thin Films on a Silicon Dioxide Surface Using an Ultra-slow Deposition Technique
   R. Hayakawa, M. Petit, Y. Wakayama,and T. Chikyow

   J. Phys. Chem. C, 2007; 111: 18703-18707.