By Josh Perry, Editor
[email protected]

Scientists at Northwestern University (Evanston, Ill.) have created a blueprint for fabricating new heterostructures from different 2-D materials, which could lead to the development of building blocks for next-generation computers and electronics with enhanced properties.

Researchers are developing new methods for layering nanomaterials. 
(Cain, Hanson and Dravid)

According to a report from AIP Publishing, the researchers have created an easy and readily deployable way to stack nanomaterials into orders not seen in nature with the goal of creating a library of heterostructures that details properties and applications.

The article explained. “In this work, the scientists looked to solve these fabrication issues. After identifying trends in the literature, they tested different conditions to map out the different parameters required to grow specific heterostructures from four types of 2-D materials: molybdenum disulfide and diselenide, and tungsten disulfide and diselenide. To fully characterize the atomically thin final products, the scientists used microscopy and spectrometry techniques.”

Based on the time-temperature-transformation diagrams of classic material science, the researchers have developed a unified time-temperature-architecture diagram to package their findings.

“Using these diagrams, the researchers developed a unique library of nanostructures with physical properties of interest to physicists and materials scientists,” the article added. “The Northwestern University scientists are now examining the behaviors displayed by some materials in their library, like the electron flow across the stitched junctions between materials.”

The research was recently published in the Journal of Applied Physics. The abstract read:

“The advent of two-dimensional materials and van der Waals (vdW) heterostructures has been a boon for the nanoscience community, enabling the fabrication of nanostructures with atomic-scale precision, resulting in high performance opto-electronic devices. Yet, while vdW heterostructures have been widely studied, their fabrication remains rudimentary, relying upon physical stacking and ad hoc collections of recipes, rather than a rational framework.

“Here, we report our work on the synthesis of vdW heterostructures and monolayer alloys of MoS₂-WS₂ and MoSe₂-WSe₂ and the creation of a unifying, diagrammatic approach to heterostructure growth in these materials systems, which we call Time-Temperature-Architecture (TTA) diagrams.

“We demonstrate the temperature tunable synthesis of in-plane, vertical, and hybrid heterostructures, as well as monolayer alloys within the MoS₂-WS₂ and MoSe₂-WSe₂ systems. We use the TTA framework to add previously unexplored entries to this collection: the first ever single-step growth of MoSe₂-WSe₂ vertical heterostructures and Mo_1-xW_xSe₂ alloys, and a new MoS₂-WS₂ hybrid architecture that combines the morphologies of both vertical and in-plane heterostructures.

“The TTA diagrams are a simple framework for vdW heterostructure and alloy growth, which we believe will be crucial, and enable further work on heterostructures and alloys of MoS₂-WS₂ and MoSe₂-WSe₂.”