Exploring Oxides for a Greener Generation of Computing

As silicon-based electronics reach their limits in computing and AI’s energy demands grow, researchers are seeking materials that could power a more energy-efficient generation of computing. 

One of those researchers is Seung Sae Hong, an assistant professor of materials science and engineering at the University of California, Davis. Hong investigates freestanding oxide membranes, compounds formed when oxygen combines with a chemical element, such as a metal. 

The study of freestanding oxide membranes is relatively new, having emerged in 2016. Researchers like Hong are answering fundamental questions about the material’s behavior. 

“These materials have peculiar electronic properties,” Hong said, “and the entire community working on oxides is wondering whether these electronic properties can be used for the next generation of electronics.” 

Drawn to the Unknown

Hong first became interested in oxides during his postdoctoral research at Stanford University. His advisor, Professor Harold Hwang, introduced him to an emerging field focused on the unusual electronic behaviors of oxide materials. Hong was drawn to the idea of investigating something completely unfamiliar. 

“I thought it was very cool because I wanted to explore something I didn’t understand for my Ph.D.,” Hong said. 

Once he began researching oxides, Hong learned that these materials have different functionalities. Their electronic and magnetic properties make them attractive for future electronics, while their electrochemical properties could advance energy conversion and storage technologies. 

Hong became deeply interested in oxides’ potential for impact across the fields of sustainable energy technologies and electronics, the latter of which is largely fueled by silicon. 

Silicon reigns as the material of choice for computing chips. How electrons function in silicon has been widely understood for decades, leading to its ubiquity in laptops, cell phones, wearable technology and cars. However, silicon-based computing is approaching physical and performance limits, creating demand for materials that operate in ways silicon cannot. 

Computing More Efficiently

Hong aims to find a material that performs more efficiently than silicon. He uses the example of a large language model like ChatGPT versus the human brain.

“Even though AI performance is great, the energy efficiency is not,” Hong said. “One of my big motivators is to develop some material that can behave the way brain power operates, so we can reduce energy consumption to much less than silicon electronics.” 

Unlike silicon, electrons in oxides can interact in unusual ways, producing quantum behaviors that dramatically alter how electricity flows through the materials. Hong studies whether those behaviors can be harnessed to develop more energy-efficient technologies. 

For instance, oxides can switch between insulating and conducting states by inserting or removing oxygen, allowing researchers to effectively turn electrical pathways on and off. This feature could enable memory and computation to run on the same device, leading to faster electronics. It also highlights the versatility of oxide membranes. 

Beyond computing, the same properties could help researchers better understand energy-conversion processes that are important for future technologies, such as hydrogen-based energy systems.

Stretching the Possibilities

Hong has also discovered in his research that when oxides, a type of ceramic, are stretched into a nanometer-thin layer, they become flexible. Unlike familiar ceramics such as coffee mugs, which crack under stress, these ultrathin oxide membranes stretch like rubber and don’t fracture. Even more surprising, stretching the membrane changes its electronic and magnetic properties.

Hong and his group are investigating the stretched membrane to determine exactly why these changes occur and what they could mean for future electronics, such as wearable devices and sensors. His group is also exploring what happens when multiple atomically thin oxide layers are stacked together, creating new interfaces where unexpected behaviors may emerge.

While the potential of oxides is grand, and the overarching goals of Hong's research are wide-reaching, oxide membranes remain a relatively young area of study. For Hong, it is not the scale of those possibilities that he appreciates most, but the day-to-day rhythm of solving problems with his students and collaborating with other researchers.

“I’m really enjoying coming up with ideas with my students and exchanging ideas with other experts,” Hong said. “Whether it be an experimental challenge in the lab or a fundamental question about the phenomena we are observing, we are solving one problem at a time.”