While researchers have long known that thin films of bismuth telluride (Bi2Te3)—which converts heat into electricity or electricity into cooling—can be combined on top of a gallium arsenide (GaAs) foundation to create cooling devices for electronics, a team from North Carolina State University (NCSU) and RTI International have answered the question as to how they are combined for the first time, a breakthrough that could lead to more efficient technologies for powering or cooling electronics.
Scientists have been unable to determine how the two materials are held together because their atomic structures are not compatible, preventing a chemical bond from forming. However, using ‘Super-X’ x-ray spectroscopy technology in combination with an aberration-corrected scanning transmission electron microscope, the NCSU and RTI researchers were able to determine that the materials were in fact held together by the addition of a thin surface layer of gallium telluride, which is created during the development process, and weak electrical forces known as van der Waals bonds. The gallium telluride is a result of a reaction between the GaAs substrate and molecules containing tellurium, which is introduced along with molecules containing bismuth into the vapor deposition chamber where the process takes place.
“We’ve used state-of-the-art technology to solve a mystery that has been around for years,” James LeBeau, Ph.D., an assistant professor of materials science and engineering at NCSU, said. “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.”
For more information, visit RTI International.
