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.

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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 [3], 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) [4] and liquid phase exfoliation (LPE) [5] 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 [10], crossbar arrays of memristors [11] and memtransistors [12], self-powered antennas [13] and advanced cameras [14]. The authors of some of these works have started to partner with companies to try to introduce their developments in the market [15].

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 [16]. 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 [17], 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.

References

[1]         Vaux, D. L. Know when your numbers are significant, Nature 492, 180–181(2012).

[2]         Frommlet, F. Improving reproducibility in animal research, Scientific Reports 10, 19239 (2020).

[3]         Novoselov, K. et al. Two dimensional atomic crystals. Proc. Nat. Acad. Sci. 102, 10451-10453 (2005).

[4]         Li, X. et al. Large-Area Synthesis of High-Quality and Uniform Graphene Films on Copper Foils. Science 324, 1312-1314 (2009).

[5]         Hernandez, Y. et al. Production of Graphene by Liquid-Phase Exfoliation of Graphite. Nat. Nanotechnol. 2008, 3, 563−568.

[6]         Akinwande, D. et al. Graphene and two-dimensional materials for silicon technology. Nature 573, 507–518 (2019).

[7]         Li, M.-Y. et al. How 2D semiconductors could extend Moore’s law. Nature 567, 169–170 (2019).

[8]         Lin, S. et al. Solution-processable 2D semiconductors for highperformance large-area electronics. Nature 562, 254–258 (2018).

[9]         Li, N. et al. Large-scale flexible and transparent electronics based on monolayer molybdenum disulfide field-effect transistors. Nat. Electron. 3, 711-717 (2020).

[10]      Polyushkin, D. K. et al. Analogue two-dimensional semiconductor electronics. Nat. Electron. 3, 486–491 (2020).

[11]      Chen, S. et al. Wafer-scale integration of two-dimensional materials in high-density memristive crossbar arrays for artificial neural networks. Nat. Electron. 3, 638-645 (2020).

[12]      Lee, H.-S. et al. Dual-Gated MoS2 Memtransistor Crossbar Array. Adv. Funct. Mater. 2003683 (2020).

[13]      Zhang, X. et al. Two-dimensional MoS2-enabled flexible rectenna for Wi-Fi-band wireless energy harvesting. Nature 566, 368–372 (2019).

[14]      Goossens, S. et al. Broadband image sensor array based on graphene–CMOS integration. Nat. Photon. 11, 366–371 (2017).

[15]      Website of the company Baijieteng Technology Corporation, http://bjtiot.com/english/ (accessed on November 24th 2020).

[16]      Shi, Y. et al. Electronic synapses made of layered two-dimensional materials. Nat. Electron. 1, 458–465, (2018).

[17]      Lanza, M., Smets, Q., Huyghebaert, C., Li, L.-J. Yield, variability, reliability, and stability of two-dimensional materials based solid-state electronic devices, Nat. Comm. 11, 5689 (2020).

 

 

Mario Lanza

Associate Professor, King Abdullah University of Science and Technology

Mario Lanza is an Associate Professor of Materials Science and Engineering at the King Abdullah University of Science and Technology (KAUST), in Saudi Arabia since October 2020. Dr. Lanza got his PhD in Electronic Engineering with honors in 2010 at Universitat Autonoma de Barcelona. During the PhD he was a visiting scholar at The University of Manchester (UK) and Infineon Technologies (Germany). In 2010-2011 he was NSFC postdoc at Peking University, and in 2012-2013 he was Marie Curie postdoc at Stanford University. On October 2013 he joined Soochow University as Associate Professor, and in March 2017 he was promoted to Full Professor. Prof. Lanza has published over 120 research papers, including Science, Nature Electronics, Nature Chemistry, and IEDM, edited a book for Wiley-VCH, and registered four patents (one of them granted with 5.6 Million CNY). Prof. Lanza has received the 2017 Young Investigator Award from Microelectronic Engineering (Elsevier), and the 2015 Young 1000 Talent award (among others), and in 2019 he was appointed as Distinguished Lecturer of the Electron Devices Society (IEEE-EDS). Prof. Lanza is Associate Editor of Scientific Reports (Nature) and Microelectronic Engineering (Elsevier), and serves in the board of many others, like Advanced Electronic Materials (Wiley-VCH), Nanotechnology and Nano Futures (IOP). He is also an active member of the technical committee of several world-class international conferences, including IEEE-IEDM, IEEE-IRPS, IEEE-IPFA and APS. Prof. Lanza leads a research group formed by 10-15 PhD students and postdocs, and they investigate how to improve electronic devices using 2D materials, with special emphasis on two-dimensional (layered) dielectrics and memristors for non-volatile digital information storage and artificial intelligence computing systems.