Yield, variability, reliability, and stability of electronic devices made of two-dimensional layered materials
Statistical analyses are extremely important in the field of two-dimensional layered materials, especially when using scalable methods like chemical vapour deposition and liquid phase exfoliation because these processes often result in larger density of defects, inhomogeneity, and variability.
Reproducibility of scientific experiments is a big concern [1-2]. In the field of two-dimensional (2D) layered materials (LM) we have witnessed how top journals have sometimes published articles in which ground-breaking claims were supported by scarce data. In many cases, the excuse was that the materials were obtained via mechanical exfoliation of bulk crystal powder , which does not allow the fabrication of multiple devices in parallel and strongly difficult getting data from hundreds of 2D-LMs based structures.
Fortunately, around 2008 scalable methods to synthesize 2D-LMs were developed, being chemical vapour deposition (CVD)  and liquid phase exfoliation (LPE)  those that have raised most interest. These developments have attracted the interest of the semiconductors industry, which is hungry of novel nanomaterials and nanostructures that could extend the Moore’s law, and/or contribute to the development of devices beyond the complementary metal-oxide-semiconductor (CMOS) technology [6-7].
In the process of integrating 2D-LMs in semiconductor production lines, researchers based at universities and institutes could play an important role because they could choose to employ industry-compatible methods, and at the same time they do not have the multiple restrictions (in terms of contamination and high processing costs) that companies have. This flexible position allows them to try new materials and device configurations using CVD and LPE, which could produce important advances in this field. As an example, most state-of-the-art electronic circuits made of 2D-LMs have been developed at universities and research institutes [8-14], including circuital demonstrations of logic gates [8-9], operational amplifiers , crossbar arrays of memristors  and memtransistors , self-powered antennas  and advanced cameras . The authors of some of these works have started to partner with companies to try to introduce their developments in the market .
However, it should be highlighted that the crystallographic structure of 2D-LMs synthesized using state-of-the-art scalable methods (i.e. CVD, LPE) still contains too many defects (e.g. lattice distortions, impurities, grain boundaries, dangling bonds at the junctions), which increases the inhomogeneities in the 2D-LMs sheet/film . Therefore, it is extremely important that studies using CVD and LPE to synthesize 2D-LMs for electronic devices and circuits include abundant information about yield, variability, reliability and stability of the main parameters and figures-of-merit.
In our Comment article, recently published in Nature Communications , we clearly detail the most important considerations to take into account in this direction. All advices given have been supervised by colleagues working in the industry, and following them should increase the quality of journal papers and accelerate the introduction of 2D-LMs in electronic devices and circuits, with the consequent benefit for our society.
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