An international team of scientists has been able to create a microscopic transistor made up of one single molecule and a number of atoms.
The team that created the transistor built the device using a scanning tunneling microscope (STM), then positioned an organic molecule on a small piece of indium arsenide, and afterward placed metal atoms around it.
"The molecule is only weakly bound to the InAs template," said Stefan Fölsch, a physicist who led the team. "So, when we bring the STM tip very close to the molecule and apply a bias voltage to the tip-sample junction, single electrons can tunnel between template and tip by hopping via nearly unperturbed molecular orbitals, similar to the working principle of a quantum dot gated by an external electrode. In our case, the charged atoms nearby provide the electrostatic gate potential that regulates the electron flow and the charge state of the molecule."
Basically, the transistor works very similarly to how any other transistor would. Once voltage is applied, the transistor provides a different output based on its inner workings. Transistors are the basic building blocks of microchips.
The surface-bound molecule rotates differently depending on its charge state, the scientists said. It is "markedly different from the conventionally expected behavior and could be important for future device technologies as well as for fundamental studies of electron transport in molecular nanostructures," they said.
Of course, while it is extremely small, it is only one single transistor, which isn't much use by itself. There is a substantial difference between this and a conventional semiconductor quantum dot, which is typically made up of hundreds of thousands of atoms.
Still, they're glad their prediction was correct. "The molecule adopts different rotational orientations, depending on its charge state," said Steven Erwin, a density-functional theory expert and physicist in the Center for Computational Materials Science at the Naval Research Laboratory. "We predicted this based on first-principles calculations and confirmed it by imaging the molecule with the STM."
While this certainly is a step forward, it seems as though IBM's new 7-nanometer chip will remain the chip with the smallest transistors for now. This chip has around double the power and performance of chips currently on the market, and is even smaller than the 10-nm chips being worked on by the likes of Intel. To put this into perspective, the 7-nm transistors are about 1/10,000th the width of a human hair and around three times the width of a strand of DNA.
Both studies seem to continue to confirm Moore's Law, which was first observed by Intel co-founder Gordon Moore, saying that the number of transistors found on a chip was doubling every year and that it would continue to do so for the foreseeable future.
The team that conducted the study included researchers from the U.S. Naval Research Laboratory and the NTT Basic Research Laboratories in Japan. The study was first published in Nature Physics.
