Breakthrough in 2D Crystal Transfer Paves the Way for Next-Generation Electronics

University of Manchester researchers develop a new technique for clean assembly of van der Waals heterostructures using inorganic stamps.

Researchers at the University of Manchester have achieved a significant breakthrough in the transfer of 2D crystals, a development that holds great promise for the commercialization of next-generation electronics. In a recent article published in Nature Electronics, the team led by Professor Roman Gorbachev from the National Graphene Institute details a novel technique that utilizes fully inorganic stamps to create the cleanest and most uniform 2D material stacks to date. This advancement not only improves the quality of the assembled structures but also brings us closer to the realization of electronic devices based on 2D materials.

Precise “Pick and Place” Technique Enables Atomically Clean Interfaces

The team at the University of Manchester developed a technique that utilizes an inorganic stamp to precisely “pick and place” 2D crystals into van der Waals heterostructures. This process takes place within an ultra-high vacuum environment, resulting in atomically clean interfaces over extended areas. Compared to existing techniques, this new method represents a significant leap forward and addresses one of the major challenges in the commercialization of 2D material-based electronic devices.

Minimizing Strain Inhomogeneity in Assembled Stacks

The rigidity of the new stamp design plays a crucial role in minimizing strain inhomogeneity in assembled stacks. The researchers observed a remarkable decrease in local variation at “twisted” interfaces, reducing strain inhomogeneity by over an order of magnitude compared to current state-of-the-art assemblies. This improvement in stack quality opens up new possibilities for engineering designer crystals with novel hybrid properties at the atomic level.

Overcoming Contamination and Transfer-Induced Strain

While various techniques have been developed to transfer individual layers of 2D materials, most rely on organic polymer membranes or stamps for mechanical support during the transfer process. Unfortunately, this reliance on organic materials introduces surface contamination, even in controlled cleanroom environments. The presence of contaminants between 2D material layers hinders the development of industrially viable electronic components. The team’s new hybrid stamp, comprising a flexible silicon nitride membrane and an ultrathin metal layer, overcomes these limitations by providing mechanical support without introducing contamination.

Scaling Up the Transfer Process for Grown 2D Materials

The researchers successfully demonstrated their technique using microscopic flakes obtained through the “sticky tape” method. They were able to scale up the transfer process to handle larger-sized materials grown from the gas phase, achieving clean transfer of millimeter-scale areas. This scalability is crucial for the potential applications of 2D materials in next-generation electronic devices.

Conclusion:

The breakthrough achieved by the University of Manchester researchers in the transfer of 2D crystals using inorganic stamps marks a significant milestone in the development of next-generation electronics. The precise “pick and place” technique enables the creation of atomically clean interfaces, while the new stamp design minimizes strain inhomogeneity in assembled stacks. Overcoming the challenge of contamination and transfer-induced strain brings us closer to the commercialization of 2D material-based electronic components. With the ability to work with grown 2D materials at larger sizes, the potential applications of these materials in the field of electronics are vast. As researchers continue to refine these techniques, we can anticipate further advancements in the utilization of 2D materials for a wide range of technological applications.