PQI Seminar: Dr. Mario Hofmann, Dr. Ya-Ping Hsieh

Dr. Mario Hofmann and Dr. Ya-Ping Hsieh from the National Taiwan University and Academia Sinica gave a talk titled "Why and How to Integrate 2D Materials in Future Electronics" in the Pittsburgh Quantum Institute Fall Seminar series on Nov. 17th, 2020.

Abstract: 2D materials are atomically thin nanostructures that are considered enabling elements in future electronics due to their unique geometry and exciting physical properties. To realize such applications, however, challenges in materials quality and production have to be addressed. In this talk we will first introduce a novel growth method that can enhance the scale, reliability, and controllability of 2D materials synthesis. Through control of the gas phase kinetics of the chemical vapor deposition process, efficient 2D materials growth could be achieved in atomically confined conditions. This advance permits the synthesis of 2D materials, such as graphene and TMDCs, at unprecedented scale and at crystalline qualities that rival exfoliated materials. Moreover, synthesis in the van-der-Waals gap of a host 2D material is demonstrated to facilitate a novel 2D crystallization process that yields novel transition-metal monochalcogenides with unexpected thermodynamic properties and finely adjustable thickness. Finally, the atomic length scales in confined growth enable controllable multi-precursor synthesis of diluted magnetic semiconductor 2D materials. The high quality of thus grown materials reveal novel interfacial ordering effects of 2D materials that are fundamentally different from bulk and present both challenges and opportunities towards their integration in electronics. Organization of ionic impurities on high quality graphene was shown to introduce a novel scattering process, that modulates graphene’s mobility by six times and is independent of charge concentration, necessitating improvements in materials’ characterization and handling. On the other hand, ordering effects at 2D materials interfaces can provide routes towards enhanced fabrication and performance of electronic devices. Interaction of graphene surfaces with gaseous adsorbates was shown to stabilize graphene in chemical reactions, permitting atomic-precision lithography approaches for large-scale semiconductor fabrication. Finally, assembly of monolayer water films on graphene under nanomechanical confinement was shown to produce a novel ferroelectric ice phase that can be exploited in mechanical memristive devices.