Researchers have achieved significant milestones in creating a high-quality thin film conductor, paving the way for longer-lasting batteries in wearable electronics and other small devices.
This breakthrough, made by scientists at The Ohio State University, the Army Research Laboratory, and MIT, highlights a material that is exceptional for its electron mobility—how easily an electrical current flows through it.
This new material is like a smooth, empty highway for electrons, allowing them to move freely without obstacles.
“We redefined what a car on this highway does—it’s like a car that can go really fast without getting encumbered by other things on the road,” explained Patrick Taylor, a physicist at the Army Research Laboratory and lead author of the study.
Future generations of electronics will benefit from this technology because it requires very little power.
“The Army is interested in low power because they don’t want to give a soldier something that hogs their battery,” Taylor said.
“The commercial sector is also looking at this technology as a potential successor to silicon, which is reaching its limits.”
The findings were published in the journal Materials Today Physics. Co-lead author Brandi Wooten, who recently earned her Ph.D. in materials science and engineering at Ohio State, noted that the researchers detected elusive oscillations in their tests, confirming the thin films were almost free of scattering—unlike natural counterparts.
“These materials, naturally speaking, just aren’t the best quality in terms of thin film growth, but we need thin films to make devices,” Wooten explained.
“This study shows we can make these materials good enough in thin film form to be used in devices. This is a stepping stone to making these materials do more.”
The research team sees great potential in these thin films, especially for their thermoelectric properties.
These films, which are very energy-efficient, could be used in various applications, including the next generation of magnetic memory in computers, powering robots or drones, and even wearable devices that keep soldiers cool under heavy gear.
The thin films, which are between 90 and 150 nanometers thick, are refined versions of a mineral called tetradymite, consisting of bismuth, tellurium, and sulfur.
Scientists have focused on perfecting tetradymite films for about 20 years due to their potential as topological insulators—materials where electrical current flows on the surface while the interior acts as an insulator. This feature reduces any loss of surface current and offers unique properties for low-power devices.
To achieve these properties, Taylor used a technique called molecular beam epitaxy (MBE), starting with the same crystal structure as tetradymite but substituting other elements to create two different compositions with distinct conduction mechanisms. Joseph Heremans, a professor at Ohio State and co-lead author of the paper, guided the selection of elements to achieve the best films.
“By lowering the carrier concentration, we can utilize these really strong and robust states on the surface,” Wooten said. “In topological insulators, the current can go in one direction on the surface, but not the other. It can’t back-scatter, making them more robust.”
This work represents an advance in not just building these films but also testing their properties in the lab. Previously, materials made for lab study were much larger. “Using this molecular beam epitaxy technique, we can now envision a pathway toward something that might fit in your computer or cell phone someday,” Taylor said.
This breakthrough could lead to significant improvements in battery life and performance for small electronics, making them more efficient and reliable for everyday use.
Source: Ohio State University.
