In recent years, topological insulators have become one of the hottest topics in physics. These new materials act as both insulators and conductors, with their interior preventing the flow of electrical currents while their edges or surfaces allow the movement of a charge.

Perhaps most importantly, the surfaces of topological insulators enable the transport of spin-polarized electrons while preventing the “scattering” typically associated with power consumption, in which electrons deviate from their trajectory, resulting in dissipation.

Because of such characteristics, these materials hold great potential for use in future transistors, memory devices and magnetic sensors that are highly energy efficient and require less power.

Bismuth telluride is well known as a thermoelectric material and has also been predicted to be a three-dimensional topological insulator with robust and unique surface states. Recent experiments with bismuth telluride bulk materials have also suggested two-dimensional conduction channels originating from the surface states. But it has been a great challenge to modify surface conduction, because of dominant bulk contribution due to impurities and thermal excitations in such small-band-gap semiconductors.

By properly tuning the gate voltage, very high surface conduction was achieved, up to 51 percent, which represents the highest values in topological insulators.”

“This research is very exciting because of the possibility to build nanodevices with a novel operating principle,” said Wang, who is also associate director of the California NanoSystems Institute (CNSI) at UCLA. “Very similar to the development of graphene, the topological insulators could be made into high-speed transistors and ultra-high-sensitivity sensors.”

“The ideal scenario is to achieve 100 percent surface conduction with a complete insulating state in the bulk,” Xiu said. “Based on the current work, we are targeting high-performance transistors with power consumption that is much less than the conventional complementary metal-oxide semiconductors (CMOS) technology used typically in today’s electronics.”

courtesy: sciencedaily.com

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