Aligning Atoms to Make World’s Smallest Letters 2009/08/20 Groups led by Yoshiaki Sugimoto of Osaka University and Oscar Custance at the National Institute for Materials Science have developed an atom-embedding technology that enabled them to write the world’s smallest letters. They succeeded in experimentally embedding single atoms in a minute metal surface. This work is promising for the possibilities it holds in new semiconductor development.

In this experiment, the probe of the atomic force microscope was very carefully brought near the tin surface, and tin atoms were replaced one at a time with silicon atoms on the probe tip. In this way the group "wrote" the letters "Si" with 12 silicon atoms on the surface. The size of the letters together was about 4 nanometers in height and width, making them the smallest letters in the world.

Major information technology companies IBM and Japan’s Hitachi have also succeeded in making letters by aligning electrons, but they did this under extremely low temperatures. The present study was the first time this had been achieved at room temperature, and the results, moreover, were stable. In addition, the group not only moved atoms but also replaced them with atoms of a different material. In this experiment it took less than an hour to write the letters "Si," but researchers say it will be possible to reduce the time to several seconds if computer controls are used in replacing the atoms. It will also be possible to change the atoms on the probe tip to embed indium or other elements in a silicon surface.

In addition to the development of semiconductors, this atom substitution technology may also contribute to the control of between-spin interaction in spintronics, which uses electron spin, and the development of quantum computers, which promise to greatly exceed the computing power of today’s computers. Future developments will be closely watched. (Keiichi Maeda)

Related Websites
- National Institute for Materials Science
http://www.nims.jp/eng/news/press/2008/10/vk3rak00000017uj.html