The amount of energy used for computing is climbing at an exponential rate. Business intelligence and consulting firm Enerdata reports that information, communication and technology accounts for 5% to 9% of total electricity consumption worldwide.
October 11, 2022
The amount of energy used for computing is climbing at an exponential rate. Business intelligence and consulting firm Enerdata reports that information, communication and technology accounts for 5% to 9% of total electricity consumption worldwide.
If growth continues unabated, computing could demand up to 20% of the world’s power generation by 2030. With power grids already under strain from weather-related events and the economy transitioning from fossil fuel to renewables, engineers desperately need to flatten computing’s energy demand curve.
Members of Jon Ihlefeld’s multifunctional thin film group are doing their part. They are investigating a material system that will allow the semiconductor industry to co-locate computation and memory on a single chip.
« Right now we have a computer chip that does its computing activities with a little bit of memory on it, » said Ihlefeld, associate professor of materials science and engineering and electrical and computer engineering at the University of Virginia School of Engineering and Applied Science.
Every time the computer chip wants to talk to memory the larger memory bank, it sends a signal down the line, and that requires energy. The longer the distance, the more energy it takes. Today the distance can be quite far—up to several centimeters.
« In a perfect world, we would get them in direct contact with each other, » Ihlefeld said.
That requires memory materials that are compatible with the rest of the integrated circuit. One class of materials suitable for memory devices are ferroelectrics, meaning they can hold and release a charge on demand. However, most ferroelectrics are incompatible with silicon and do not perform well when made very small, a necessity for modern-day and future miniaturized devices.
Researchers in Ihlefeld’s lab are playing matchmaker. Their research advances materials with electrical and optical properties that make modern computation and communication possible, a research strength of the Department of Materials Science and Engineering. They also specialize in fabrication and characterization of a range of materials, a research strength of the Charles L. Brown Department of Electrical and Computer Engineering.
Their material of interest is hafnium oxide, which is used in the manufacture of cell phones and computers today. The downside is that in its natural state, hafnium oxide is not ferroelectric.
A tip of the cap to Shelby Fields
Over the last 11 years, it has become known that hafnium oxide’s atoms can be manipulated to produce and hold a ferroelectric phase, or structure. When a hafnium oxide thin film is heated, a process called annealing, its atoms can move into the crystallographic pattern of a ferroelectric material; when the thin film is cooled, its crystalline structure sets in place.
Why formation of the ferroelectric phase happens has been the subject of much speculation. Shelby Fields, who earned a Ph.D. in materials science engineering from UVA this year, published a landmark study to explain how and why hafnium oxide forms into its useful, ferroelectric phase.
Fields’ paper, Origin of Ferroelectric Phase Stabilization via the Clamping Effect in Ferroelectric Hafnium Zirconium Oxide Thin Films, published in August in Advanced Electronic Materials, illustrates how to stabilize a hafnium oxide-based thin film when it is sandwiched between a metal substrate and an electrode.
