Scientists develop heat transistor that someday could cool chips

Posted by Rick C. Hodgin

Chicago (IL) - The cooling needs of tomorrow's semiconductors, those which keep pace with Moore's Law, will grow to extremes. There are costly new materials solutions which indicate Moore's Law will continue for the foreseeable future. But what if we had the ability to channel heat wherever we wanted it to go via electrically controlled transistors?

Several scientists working together from Finland and Italy may have found the first hints of a future solution. The new discovery is called a heat transistor. A heat transistor is basically a special kind of electrical transistor whereby, as voltage is applied, it begins to sink heat away from its source.

A theory developed in the laboratory has now been modeled and experiments have been carried out. The predicted results, according to the scientists, accurately align with the hard data observed from real-world experiments. This makes the first ever observation of the so-called Coulombic control of heat transfer in a mesoscopic electrical transistor.

In their experiments, the scientists used a copper metal island core on the scale of 180 nm x 2300 nm x 20 nm. The electrical gate itself is comprised of four superconducting aluminum leads tunnel-coupled to the metal island, and capacitively coupled to the gate electrode. As current is applied a heat transfer is observed, resulting in refrigeration.

In simple terms, when the transistor activates the metal island gets cooler. The effect is also forcible, very much like certain chemical reactions which will literally draw heat away from the surrounding materials in order to complete the combination (sometimes resulting in extreme freezing temperatures).

The experiments have shown a factor of three return regarding heat removal at the sampled temperatures. As it's cooled further even greater differentials should be seen. This heat transistor results in a tremendous new ability added to the potential arsenal of future technology applications. The experimental work was carried out jointly by the Low Temperature Laboratory and Laboratory of Physics at Helsinki University of Technology in Finland, as well as NEST CRN-INFM & Scuola Normale Superiore in Pisa, Italy.

The experiments confirm that the new heat transistor design is practical and can be used effectively. This is pioneering work and serves as the first experimental observation of such an Coulombic effect in electrical transistors.

Currently any usable products will likely only operate at extremely cold temperatures (for the superconductors to function).  Proposed early applications are micro-refrigerators and heat sensors.  Any real end products which would operate for semiconductors are still a long way off. However, these first steps in transistor-based heat transfer open up many  exciting possibilities for future research and application.