Two insulators produce highly-conductive interface

Engineers from the University of Utah and the University of Minnesota have discovered that interfacing two insulating oxide-based materials makes them highly conductive. This finding could lead to more power-efficient laptops and electric cars, and home appliances that don't need cumbersome power supplies. The engineers published their findings in a paper in APL Materials.

The team was jointly led by Berardi Sensale-Rodriguez, an electrical and computer engineering assistant professor at the University of Utah, and Bharat Jalan, a chemical engineering and materials science assistant professor at the University of Minnesota. They found that when two oxide compounds – strontium titanate (STO) and neodymium titanate (NTO) – interact with each other, the bonds between the atoms are arranged in a way that produces many free electrons. Rather ironically, STO and NTO are by themselves known as insulators – materials like glass – that are not conductive at all.

When they form an interface, however, the amount of electrons produced is a 100 times larger than possible with semiconductors. "It is also about five times more conductive than silicon [the material most used in electronics]," Sensale-Rodriguez says.

This innovation could greatly improve the efficiency of the power transistors that control the supply of electricity to items ranging from televisions and refrigerators to handheld devices, Sensale-Rodriguez says. Today, electronics manufacturers use a material called gallium nitride for the transistors in power supplies and other electronics that carry large electrical currents. But that material has been explored and optimized for many years, and likely cannot be made much more efficient. The interface between STO and NTO, however, can be at the very least as conductive as gallium nitride and likely will be much more conductive in the future.

"When I look at the future, I see that we can perhaps improve conductivity by an order of magnitude through optimizing of the materials growth," Jalan says. "We are bringing the possibility of high power, low energy oxide electronics closer to reality."

Power transistors that use this combination of materials could lead to smaller devices and appliances. Laptop computers, for example, could ditch the bulky external power supplies – the big black boxes attached to the power cords – in favor of smaller supplies that are instead built inside the computer. Such power transistors could also make large appliances that consume a lot of electricity, such as air conditioners, much more power efficient. And because there is less power wasted, these devices will not run as hot as before, says Sensale-Rodriguez, because wasted electricity usually dissipates as heat.

"It's fundamentally a different road toward power electronics, and the results are very exciting" he says. "But we still need to do more research."

This story is adapted from material from the University of Utah, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.