Tiny antennas and transistors

By Hamish Johnston at the APS March Meeting in Dallas

It’s the second day of the March Meeting and I’ve just done three video interviews, which should start appearing on physicsworld.com in April.

I also managed to make it to a few press conferences, including one on how to make extremely small transistors and antennas.

Above you can see Mark Reed of Yale University who was the first to create a transistor from a single molecule. Reed and colleagues place an organic molecule between two electrodes, which function as the source and drain in a field-effect transistor. The molecule is suspended above a third electrode, which acts as the gate.

You might think that Reed wants to make these tiny resistors to ensure that Moore’s law – the relentless miniaturization of computer chips – continues right down to the molecular level. However, he points out that the biggest threat to Moore’s law today is how to get rid of all the heat generated by a dense clump of tiny transistors. The molecular transistor doesn’t help much with that, and Reed is more interested in studying the fundamental physics of these quantum devices.

Also speaking at the press conference was Niek van Hulst of the Institute of Photonics Science in Barcelona. Van Hulst and colleagues have made tiny antennas that can broadcast and receive visible light.

Such antennas could be put very close to a molecule of interest for example, and capture all the light emitted by the molecule. Conversely it could also be used to direct intense light at just one molecule. Both of these abilities could prove very useful for molecular spectroscopy.

The team has also managed to put a tiny antenna on a scanning tunnelling microscope (STM) tip. Since the antenna is much smaller than the wavelength of the light it emits, such a set-up could be used to image molecules with resolutions much smaller than the wavelength of the light – beating the diffraction limit.

The most beautiful application though, was using an array of antennas coupled to quantum dots, which broadcast the flickering light of quantum noise within the dots.