Dec 19 2018
Over the past six decades, the decreased power consumption, increased storage capacity, and constant miniaturization of electronic devices have benefited the electronics sector and the average consumer.
Cross-sectional view of the stack of two-dimensional materials. The monolayer electrolyte in the middle allows the ions (pink spheres) to be toggled between two locations. The location of the ions sets the state of the memory. (Image credit: Fullerton Group)
Yet, this period of scaling that proved helpful to people is quickly reaching an end. This is because novel materials and innovative engineering methods are required to continue the trend of reduced power consumption and miniaturization of electronic devices.
Now, that challenge is being tackled by Susan Fullerton, assistant professor of chemical and petroleum engineering at the University of Pittsburgh’s Swanson School of Engineering, through the development of advanced electronics based on all two-dimensional (2D) materials. Such “all 2D” materials are akin to a paper sheet—provided the paper has a thickness of just one molecule. In recognition of Fullerton’s research on these extremely thin materials, the National Science Foundation (NSF) has granted a $540,000 CAREER award, which supports early-career faculty members who have the ability to serve as academic role models in education and research and also to lead advancements in the mission of their organization or department.
The advent of new computing paradigms is pushing the limit of what traditional semiconductor devices can provide. For example, machine learning will require nanosecond response speeds, sub-volt operation, 1,000 distinct resistance states, and other aspects that no existing device technology can provide. We’ve known for a long time that ions—like the ones in lithium-ion batteries—are very good at controlling how charge moves in these ultra-thin semiconductors. In this project, we are reimagining the role of ions in high-performance electronics. By layering successive molecule-sized layers on top of each other, we aim to increase storage capacity, decrease power consumption, and vastly accelerate processing speed.
Dr Susan Fullerton, Assistant Professor, Department of Chemical and Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh
In order to develop this all 2D device, Fullerton and her team created a novel type of electrolyte, or an ion-containing material, which has a thickness of just one molecule. This “monolayer electrolyte” will eventually introduce novel functions that can be applied by the electronic materials community to study the important characteristics of innovative semiconductor materials and also to create electronics that have fully new device properties.
Dr Fullerton stated that there are a number of critical application spaces where the methods and materials devised in this CAREER research can possibly have an impact: security, brain-inspired computing, and information storage, to be specific.
Apart from creating the monolayer electrolytes, the NSF award will support a postdoctoral researcher and PhD student, and also an outreach program to encourage engagement and curiosity of underrepresented and K-12 students in materials for sophisticated electronics. Dr Fullerton has particularly developed an activity in which students can observe how the polymer electrolytes utilized in this research are able to crystallize in real time with the help of a low-cost camera connected to an iPad or smartphone. The CAREER award will also enable Dr Fullerton to offer this microscope to classrooms so that both teachers and students can continue the exploration.
“When the students get that portable microscope in their hands—they get really creative,” she stated. “After they watch what happens to the polymer, they go exploring. They look at the skin on their arm, the chewing gum out of their mouth, or the details of the fabric on their clothing. It’s amazing to watch this relatively inexpensive tool spark curiosity in the materials that are all around them, and that’s the main goal.”
Dr Fullerton also observed that her study provides a truly new method to ion utilization, which the semiconductor community has normally avoided.
Ions are often ignored because if you cannot control their location, they can ruin a device. So the idea of using ions not just as a tool to explore fundamental properties, but as an integral device component is extremely exciting and risky. If adopted, ions coupled with 2D materials could represent a paradigm shift in high-performance computing because we need brand new materials with exciting new physics and properties that are no longer limited by size.
Dr Susan Fullerton, Assistant Professor, Department of Chemical and Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh