Solving the puzzle of 2D disorder

The players try to find the solution by putting together clues. Finding the right answers to those puzzles is more about logic and strategy than it is about being a wordsmith.

Using a surprisingly comparable process, an interdisciplinary team ofNorthwestern Engineering researchers pieced together a method to determine how different 2D materials respond to disorder.

The analysis method will lead to a better understanding of disorder potentials in 2D materials to help make faster transistors, as well as better gas sensors that can more easily discriminate different gases.

The paper "Field-effect Conductivity Scaling for Two-dimensional Materials with Tunable Impurity Density" was published in the journal 2D Materials.

Mark Hersam is the Walter P. Murphy Professor of Materials Science and Engineering. The paper was written by a candidate in the research group.

In science, disorder refers to charges that can scatter an electron. Graphene is a 2D material that is several atoms thick.

The performance of 2D materials can be improved by order characterization. There is a universal curve that serves as a sign of that disorder. The behaviors all represent individual threads of an overall tapestry.

The science and games you play on your phone are very similar to the games you play in the newspaper.

Using 2D material samples developed by the Hersam and Dravid groups, Grayson and his team implemented a new method to measure electrical conductivity curves. When the disorder is frozen in place, the charges that constitute it are free to shift around until they reach equilibrium.

The individual curves look like puzzle pieces. The researchers used an empirical rule to figure out all the curves.

It sounds familiar?

Physical arguments were used to understand why this rule works. They solved the problem of how each material responds to a specific class of flaws.

The impressive continuity of this picture when all the puzzle pieces were in place inspired us to dig deeper into the physics to understand why this behavior is happening. The same mentality that the general public uses to solve crosswords is used here.

Implications for 2D materials research can be found in these findings.

Rather than seeing individual devices made from the same 2D materials as a bunch of puzzle pieces that each have to be studied independently, you can now locate where a given sample fits into the previously solved puzzle.

More information: Chulin Wang et al, Field-effect conductivity scaling for two-dimensional materials with tunable impurity density, 2D Materials (2022). DOI: 10.1088/2053-1583/ac72b0