Tellurium-Based Material Can Help Create the First-Ever, Smallest Transistors

Thanks to a new Army-funded project, a material from tellurium—a rare earth element—can potentially create the world’s tiniest transistor.

Billions of very small switches, known as transistors, are used by computer chips to process data. The computer is faster when more transistors are integrated into a chip.

A new project carried out at Purdue University in association with Washington University in St. Louis, Michigan Technological University, and the University of Texas at Dallas, discovered that the material—molded in the form of a one-dimensional (1D) DNA helix and embedded in a nanotube composed of boron nitride—can build a field-effect transistor that has a diameter of just 2 nm.

Commercially available transistors are composed of bulkier silicon and span between 10 and 20 nm in scale.

This research reveals more about a promising material that could achieve faster computing with very low power consumption using these tiny transistors. That technology would have important applications for the Army.

Joe Qiu, Program Manager, Army Research Office

The Army Research Office is part of the U.S. Army Combat Capabilities Development Command’s Army Research Laboratory, which supported this study.

This Army-funded study was published in the Nature Electronics journal. The Army is working on speed, accuracy, and integration to ensure that the capability development process of the Army is flexible and adaptable enough to align with the speed of technology change.

This tellurium material is really unique. It builds a functional transistor with the potential to be the smallest in the world.

Dr Peide Ye, Richard J. and Mary Jo Schwartz Professor, Electrical and Computer Engineering, Purdue University

One technique to reduce the size of field-effect transistors—the kind found in a majority of the electronic devices—is to construct the gates surrounding nanowires. These thinner nanowires are protected inside nanotubes.

Along with his research team, Ye worked to make tellurium as minute as a single atomic chain and subsequently built transistors using these ultrathin nanowires or atomic chains.

The researchers initially developed 1D-chains of tellurium atoms and were amazed to discover that the atoms present in the 1D-chains wiggle. Such wiggles were observed via transmission electron microscopy imaging carried out at the University of Texas at Dallas and also at Purdue University.

“Silicon atoms look straight, but these tellurium atoms are like a snake. This is a very original kind of structure,” added Ye.

The wiggles are the result of atoms powerfully bonding to one another in pairs to create DNA-like helical chains and subsequently stacking through weak forces known as van der Waals interactions to create a tellurium crystal.

Such van der Waals interactions make tellurium a more effective material for 1D-nanowires or single atomic chains when compared to others because it is easier to accommodate into a nanotube, added Ye.

Because a nanotube’s opening cannot be smaller than the size of a single atom, tellurium helices of atoms can potentially realize smaller nanowires and thus smaller transistors.

The scientists were able to create a transistor in which a tellurium nanowire was embedded in a boron nitride nanotube. A boron nitride nanotube of high quality effectively insulates tellurium, thereby making it feasible to develop a transistor.

Next, the researchers will optimize the device to further improve its performance, and demonstrate a highly efficient functional electronic circuit using these tiny transistors, potentially through collaboration with ARL researchers.

Joe Qiu, Program Manager, Army Research Office

Apart from the Army Research Office, the Air Force Office of Scientific Research, the National Science Foundation, and the Defense Advanced Research Projects Agency partly financed the study.