A team of researchers from Carnegie Mellon University has recently developed a groundbreaking method for producing large quantities of a material that could revolutionize the field of two-dimensional (2D) semiconductors. Their work, published in ACS Applied Materials & Interfaces in December 2024, promises to enhance the performance of photodetectors and pave the way for the next generation of light-sensing and multifunctional optoelectronic devices.
Semiconductors are at the heart of modern electronics, powering everything from smartphones and laptops to AI technologies. These materials control the flow of electricity by acting as a bridge between conductors (which allow electricity to flow freely) and insulators (which block it). According to Xu Zhang, assistant professor of electrical and computer engineering at Carnegie Mellon, the work done by his team is vital to advancing electronics and optoelectronics.
“We aim to develop a new class of photodetectors, devices that detect light and have a wide range of potential applications,” Zhang explained. “To achieve this, we needed materials that are nearly atom-thick—essentially 2D—allowing for enhanced performance and tunability.”
Currently, the semiconductor industry relies heavily on CMOS (complementary metal-oxide-semiconductor) technology, which combines p-type (positive) and n-type (negative) materials to create energy-efficient circuits. While n-type 2D materials are abundant, finding suitable p-type 2D materials has been a major challenge—until now.
Zhang’s team sought to identify a powerful p-type material that could break this bottleneck in ultra-thin electronics. After extensive research, they identified tellurium—a conductive metalloid element— as a promising candidate. Tellurium, which resides in Group 16 of the periodic table, has long been recognized as a p-type material. However, its potential as a 2D material had yet to be fully explored.
Through their research, the team discovered that 2D tellurium exhibited the highest mobility of any p-type material they tested—at an impressive 1450 cm²/Vs. This high mobility allows devices built with tellurium to conduct electricity extremely quickly, making them ideal for high-speed applications. Moreover, tellurium is far more stable in air than the commonly used alternative, black phosphorus, meaning it doesn’t degrade as easily and remains efficient for longer periods.
“This physical vapor deposition method for growing tellurium enriches the pool of 2D semiconductor materials,” said Tianyi Huang, a graduate student in mechanical engineering and first author of the paper. “Its excellent electrical performance and p-type properties make it a strong contender for applications in high-speed CMOS circuits, photodetectors, energy harvesting, and beyond.”
Beyond its high performance, the tellurium-based photodetector is highly tunable, which allows its parameters to be adjusted for a variety of uses—a feature that is not common in other photodetectors. This flexibility opens up new possibilities in a wide range of applications, from photodetection to advanced electronic circuits.
The research was an interdisciplinary effort, with collaboration from Sheng Shen, professor of mechanical engineering at CMU, and his team. Shen expressed excitement about the potential of 2D p-type tellurium: “With its unique properties, tellurium holds great promise for applications in both photodetection and electronics. We are eager to explore its full potential.”
As the field of 2D materials continues to evolve, this breakthrough in creating high-performance, atom-thin semiconductors marks an important step toward more efficient, versatile, and high-speed electronics. The team at Carnegie Mellon University looks forward to further developing this discovery, pushing the limits of 2D materials to revolutionize technology as we know it.
By Impact Lab
