Realization of Coupled Quantum Dot Device Using Carbon Atom Single Layer Sheet!

Opening the Way to Development of Integrated Nano Quantum Devices Using New Carbon Material

2009.07.10

National Institute for Materials Science
RIKEN

A team led by Dr. Satoshi Moriyama, a MANA Independent Scientist at the International Center for Materials Nanoarchitectonics, National Institute for Materials Science, in joint research with a group headed by Dr. Koji Ishibashi, Chief Scientist of the RIKEN, succeeded in fabricating a coupled double quantum dot device by coupling two quantum dots using a graphene sheet consisting of a single atomic layer in which carbon atoms are arranged in a bee's nest shape.

Abstract

  1. A team led by Dr. Satoshi Moriyama, a MANA Independent Scientist at the International Center for Materials Nanoarchitectonics (MANA; Director-General: Masakazu Aono), National Institute for Materials Science (NIMS; President: Sukekatsu Ushioda), in joint research with a group headed by Dr. Koji Ishibashi, Chief Scientist of the Institute of Physical and Chemical Research (RIKEN; President: Ryuji Noyori), succeeded in fabricating a coupled double quantum dot device by coupling two quantum dots using a graphene sheet consisting of a single atomic layer in which carbon atoms are arranged in a bee’s nest shape.
  2. In this research, two quantum dots in close proximity, which confine electrons, and the device structure that controls electrical transmission, including electrodes, etc., were all fabricated in a single graphene sheet by direct processing of a graphene sheet consisting of three layers of graphene (thickness: approximately 1nm) using the electron beam lithography and reactive ion etching techniques. The researchers also succeeded in demonstrating single electron device operation, in which the electrons in the quantum dots are transferred individually, and in modifying the coupling of the electrons between the two quantum dots utilizing the graphene gate electrode. As a result, this work realized a coupled quantum dot device, which is the most fundamental integrated nanodevice.
  3. Quantum dots are the basic structure of single electron devices and quantum bits. Because this research has shown the possibility of developing integrated nanodevices using novel carbon materials, it is expected to contribute to progress in single electron electronics using graphene materials, and the development of new functional nanoelectronics devices, or so-called “Beyond CMOS,” including quantum computers. Publication of these results in the US scientific journal “Nano Letters” is expected in the near future.
"Fig. 1 (b) SEM image of the measured device with electrode assignment. Bright areas show etched triple-layer graphene. The two isolated islands (quantum dots) are connected via two narrow constrictions to wide source and drain regions." Image

Fig. 1 (b) SEM image of the measured device with electrode assignment. Bright areas show etched triple-layer graphene. The two isolated islands (quantum dots) are connected via two narrow constrictions to wide source and drain regions.