Novel applications for coal in 2D electronic devices

Novel applications for coal in 2D electronic devices
by Clarence Oxford
Los Angeles CA (SPX) Jan 10, 2024

In a remarkable turn of events for an industry traditionally associated with fossil fuels, coal has been identified as a potential key player in the future of microelectronics. A collaborative effort involving the University of Illinois Urbana-Champaign, the National Energy Technology Laboratory (NETL), Oak Ridge National Laboratory, and Taiwan Semiconductor Manufacturing Company (TSMC) has revealed how coal, often regarded as a contributor to climate change, could significantly impact next-generation electronic devices.

Qing Cao, a professor of materials science and engineering at the University of Illinois and a co-lead of the collaboration, highlighted the transformational nature of this research. "Coal is usually thought of as something bulky and dirty, but the processing techniques we've developed can transform it into high-purity materials just a couple of atoms thick," Cao explained. The unique atomic structures and properties of these materials make them ideal for constructing some of the smallest possible electronics with performance surpassing current state-of-the-art technology.

This groundbreaking research, detailed in the journal Communications Engineering, involves a process developed by NETL that converts coal char into nanoscale carbon disks, known as "carbon dots." These dots can be connected to form atomically thin membranes, opening new avenues in two-dimensional transistor and memristor technology - essential components in advanced electronics.

The quest for smaller, faster, and more efficient electronics inevitably leads to the exploration of materials just one or two atoms thick. Atomically thin insulators, necessary for constructing functional devices like transistors and memristors, have been successfully created from carbon layers derived from coal char. The U. of I. research team led by Cao showcased two examples of two-dimensional devices, demonstrating coal's unexpected role in cutting-edge microelectronics.

In one application, the team used coal-derived carbon layers as the gate dielectric in two-dimensional transistors. This approach enabled more than double the operating speed with lower energy consumption when compared to conventional technologies. These coal-derived carbon layers are unique as they are amorphous, lacking a regular, crystalline structure. This characteristic prevents the formation of boundaries between different crystalline regions, which in other materials can lead to leakage currents and increased power consumption.

Another significant application involves memristors, which are electronic components capable of storing and processing data, a critical feature for advancing AI technology. The researchers found that using ultrathin coal-derived carbon layers as insulators allows for the rapid formation of conductive filaments with low energy consumption. This enhances the speed and power efficiency of these devices, with atomic size rings in the carbon layers confining the filament to improve data storage fidelity and reliability.

The successful demonstration of these coal-derived devices by Cao's group marks a proof-of-principle for the use of coal-based carbon in two-dimensional electronic devices. However, the challenge remains to scale up this technology for large-scale manufacturing. Cao expressed optimism about the future of this research, noting, "The semiconductor industry, including our collaborators at Taiwan Semiconductor, is very interested in the capabilities of two-dimensional devices, and we're trying to fulfill that promise." The University of Illinois plans to continue collaborating with NETL to develop a fabrication process for these coal-based carbon insulators that can be implemented in industrial settings.

Research Report:Ultrathin Quasi-2D Amorphous Carbon Dielectric Prepared from Solution Precursor for Nanoelectronics