In 2013, Hone's team demonstrated it could improve the performance of graphene by encapsulating it in boron nitride, an insulating material with a similar layered structure.
"These findings provide a demonstration of how to study 2D materials," said Hone, director of Columbia's Materials Research Science and Engineering Center. "This holds great promise for a range of applications including high-performance electronics, detection and emission of light, and chemical/bio-sensing."
In the new work, Hone's team – which includes scientists from Harvard, Cornell, University of Minnesota, Yonsei University, Danish Technical University and the Japanese National Institute of Materials Science – created layered stacks of MoS2 encapsulated in boron nitride, with small flakes of graphene overlapping the edge of the MoS2 to act as electrical contacts.
"We wanted to see what we could do with MoS2, said Gwan-Hyoung Lee, assistant professor of materials science at Yonsei. "It's the best studied 2D semiconductor, and, unlike graphene, it can form a transistor that can be switched fully 'off' – a property crucial for digital circuits."
The researchers found that room temperature mobility was improved by a factor of two. Upon cooling to low temperature, the mobility increased, reaching values of up to 50 times those measured previously. These samples also showed strong oscillations in resistance with magnetic field, which had not been seen in any 2D semiconductor.
Hone concluded: "With further progress, we hope to establish 2D semiconductors as a new family of electronic materials that rivals the performance of conventional semiconductor heterostructures."
