Extreme Bendability of Atomically Thin MoS2 Grown by Chemical Vapor Deposition Assisted by Perylene-Based Promoter

Shaping two-dimensional (2D) materials in arbitrarily complex geometries is a key to designing their unique physical properties in a controlled fashion. This is an elegant solution, taking benefit from the extreme flexibility of the 2D layers but requiring the ability to force their spatial arrangement from flat to curved geometries in a delicate balance among free-energy contributions from strain, slip-and-shear mechanisms, and adhesion to the substrate. Here, we report on a chemical vapor deposition approach, which takes advantage of the surfactant effects of organic molecules, namely the tetrapotassium salt of perylene-3,4,9,10-tetracarboxylic acid (PTAS), to conformally grow atomically thin layers of molybdenum disulphide (MoS2) on arbitrarily nanopatterned substrates. Using atomically resolved transmission electron microscope images and density functional theory calculations, we show that the most energetically favorable condition for the MoS2 layers consists of its adaptation to the local curvature of the patterned substrate through a shear-and-slip mechanism rather than strain accumulation. This conclusion also reveals that the perylene-based molecules have a role in promoting the adhesion of the layers onto the substrate, no matter the local-scale geometry

Optical Conductivity of Two-Dimensional Silicon: Evidence of Dirac Electrodynamics

The exotic electrodynamics properties of graphene come from the linearly dispersive electronic bands that host massless Dirac electrons. A similar behavior was predicted to manifest in freestanding silicene, the silicon counterpart of graphene, thereby envisaging a new route for silicon photonics. However, the access to silicene exploitation in photonics was hindered so far by the use of optically inappropriate substrates in experimentally realized silicene. Here we report on the optical conductivity of silicon nanosheets epitaxially grown on optically transparent Al2O3(0001) from a thickness of a few tens of nanometers down to the extreme two-dimensional (2D) limit. When a 2D regime is approached, a Dirac-like electrodynamics can be deduced from the observation of a low-energy optical conductivity feature owing to a silicene-based interfacing to the substrate

Non-volatile resistive switching in nanoscaled elemental tellurium by vapor transport deposition on gold

Two-dimensional (2D) materials are highly promising as resistive switching materials for neuromorphic and in-memory computing owing to their fascinating properties derived from their low thickness. However, most of the reported 2D resistive switching materials struggle with complex growth methods or limited growth area. Tellurium, a novel member of single-element 2D materials, is showing pioneering characteristics such as simplicity in chemistry, structure, and synthesis which make it highly suitable for various applications. This study presents the first memristor design based on nanoscaled elemental tellurium synthesized by vapor transport deposition (VTD) method at a temperature as low as 100 °C in full compliance with a back-end-of-line (BEOL) processing. We demonstrate that the memristive behavior of nanoscaled tellurium can be enhanced by selecting gold as the substrate material which results in a lower set voltage and reduced energy consumption. In addition, the formation of conductive paths which in turn lead to resistive switching behavior on the gold substrate is proven to be driven by the gold-tellurium interface reconfiguration during the VTD process as revealed by energy electron loss spectroscopy analysis of the interface. Our findings reveal the potential of nanoscaled tellurium as a versatile and scalable material for neuromorphic computing systems as well as the influential role of gold as electrode material in enhancing tellurium’s memristive performance

Highly Sensitive Detection of Inorganic Contamination

As the detection of inorganic contaminants is of steadily increasing importance for the improvement of yields in microelectronic applications, the aim of one of the joint research activity within the European Integrated Activity of Excellence and Networking for Nano- and Micro-Electronics Analysis (ANNA, site: www.ANNA-i3.org) is the development and assessment of new methodologies and metrologies for the detection of low concentration inorganic contaminants in silicon and in novel materials. A main objective consist in the benchmarking of various analytical techniques available in the laboratories of the participating ANNA partners, including the improvement of the respective detection limits as well as the quantitation reliablity of selected analytical techniques such as total-reflection x-ray fluorescence (TXRF) analysi