New research from North Carolina State University and RTI International has yielded new understanding of thin films, opening the door to more efficient technologies to power or cool electronics.

The compounds bismuth telluride (Bi2Te3) and gallium arsenide (GaAs) have been used together to create state-of-the-art cooling devices for electronics. Bi2Te3 converts heat into electricity or electricity to cooling.

But the mystery of combining these two semiconductors was understanding how the two materials held together. That’s because their atomic structures don’t appear to be compatible. NCSU and RTI researchers say they’ve solved the mystery. Their work is published online in Applied Physics Letters.

Gallium telluride does not react with Bi2Te3 so chemical bonding could not be holding the films together. Researchers found that the the two layers are held together by weak electrical forces. The research was supported by the Defense Advanced Research Projects Agency, or DARPA.

“We’ve used state-of-the-art technology to solve a mystery that has been around for years,” James LeBeau, an assistant professor of materials science and engineering at NCSU and co-author of the paper said in a statement. “And now that we know what is going on, we can pursue research to fine-tune the interface of these materials to develop more efficient mechanisms for converting electricity to cooling or heat into electricity.

“Ultimately, this could have applications in a wide range of electronic applications.”

RTI’s research into turning heat into power led to the spin-out Nextreme Thermal Solutions, a Durham company that developed thin-film cooling technology and power generation capabilities used in telecommunications, automotive and aerospace applications among others. Nextreme was acquired last month by St. Louis-based Laird Technologies.