Advances in Synthesis and Integration Methods for Enhanced Properties, and Applications in Emerging Nanomaterials: 2D Materials Synthesis and Device Integration
Sponsored by: TMS: Nanomaterials Committee
Program Organizers: Chang-Yong Nam, Brookhaven National Laboratory; Jung-Kun Lee, University of Pittsburgh; Zubaer Hossain, University of Delaware
Monday 8:00 AM
November 2, 2020
Room: Virtual Meeting Room 25
Location: MS&T Virtual
Session Chair: Chang-Yong Nam, Brookhaven National Laboratory; Zubaer Hossain, University of Delaware; Jinkyoung Yoo, Los Alamos National Laboratory
8:00 AM Invited
Integration of Synthesis and Computation to Investigate Two-dimensional Transition Metal Chalcogenides: Strain, Defect, and Moiré Engineering: Yanfu Lu1; Fu Zhang1; Wenkai Zheng2; Daniel Schulman1; Lavish Pabbi1; Kazunori Fujisawa1; Ana Laura Elias1; Anna Binion1; Tomotaroh Granzier-Nakajima1; Tianyi Zhang1; Yu Lei1; Zhong Lin1; Eric Hudson1; Saptarshi Das1; Luis Balicas2; Mauricio Terrones1; Susan Sinnott1; 1Pennsylvania State University; 2Florida State University
Density functional theory (DFT) calculations predict carbon doping of transition metal dichalcogenides (TMDs) tunes their electronic structure and optical properties. We synthesized these C-doped WS2 monolayers by a plasma-assisted strategy to “gently” incorporate carbon as a substitutional anion dopant within the TMD lattice. Electrical characterization indicates that carbon may be an acceptor in WS2, thus effectively tuning its work function and making it ambipolar. We also investigated the sulfurization of thin (<50 nm) Mo2C systems using gaseous H2S. The controlled incorporation of sulfur can form metastable ternary solid solutions based on molybdenum-carbon-chalcogen whereas the presence of excessive chalcogen atoms results in phase segregation of stable carbides and sulfides. Lastly, DFT calculations predict that the majority of 2D TMDs can accommodate ±10% strain without breaking their crystal symmetry. ReSe2 and Au2Se2 at +5% epitaxial strain are predicted to possess extreme d11 coefficients at -120 pm/V and 326 pm/V, respectively.
8:30 AM Invited
Van der Waals and Remote Epitaxy for Quantum Materials Research: Jinkyoung Yoo1; 1Los Alamos National Laboratory
Growth of conventional semiconductors (3D materials) on atomically thin two-dimensional (2D) materials offers novel opportunities of recyclable device manufacturing, functionalities based on charge transfer and exciton transport, and understanding strain relaxation mechanism without structural defects. Van der Waals (vdW) and remote epitaxy techniques have been implemented to realize 3D growth on 2D. Though vdW and remote epitaxy methods have brought resonation in materials synthesis community, epitaxy strategy and full potentials of the techniques haven’t been fully understood due to their short history compared to century-long conventional epitaxy research. In the presentation several key aspects of nucleation of 3D materials on 2D materials, examples of hybrid architectures composed of 2D and 3D materials without interfacial defects, and tuning physical properties of 2D and 3D materials in the 2D/3D heterostructures prepared by van der Waals and remote epitaxy will be discussed.
9:00 AM Invited
Critical Elastic Interactions that Govern Effective Mechanical Behavior of Defective hBN and Graphene: Zubaer Hossain1; 1University of Delaware
Formation of vacancy defects is unavoidable during the fabrication of 2D materials such as graphene, hBN, WS2, or MoS2. It is commonly understood that defects substantially degrade the mechanical properties of materials, particularly their strength and toughness by increasing the intensity of the elastic field surrounding the defects. Nonetheless, the spatial coverage of the elastic fields within which enhanced activity can be expected is a subject matter of active research. In this talk, we will present the existence of a critical separation distance beyond which the elastic interactions between a pair of monovacancy defects in graphene or hBN become inconsequential. Both the strength and toughness of the lattice containing a pair of `interacting monovacancies' are either higher or smaller than that of the lattice containing a pair of `non-interacting monovacancies.' Results also show the existence of a critical orientation-angle that significantly affects the strength and toughness of the 2D lattice.
9:30 AM Invited
Ideal Graphene Schottky Junctions:
The Building Block for Reconfigurable Logic and
3D Monolithic Integration
: Ji Ung Lee1; 1SUNY Polytechnic Institute
With the end of Moore’s law, the need to reinvent the transistor is yet again upon us. Here, I will describe our efforts to develop a single device that can dynamically reconfigure into either an n- or a p-channel MOSFET, which we implement with a tunable Schottky junction. We form Schottky junctions between graphene and semiconductors, including 2D transition metal dichalcogenide (TMD) semiconductors, the material of choice for developing 3D monolithic integration. These junctions can be tuned perfectly by a gate, confirming the much sought-after Schottky-Mott limit. The tunability allows reconfigurable devices that can implement more efficient logic devices, including XNOR-Net for machine learning applications. To characterize these junctions, we use the Landauer quantum transport formalism to analyze the physics of these devices. I will conclude by briefly discussing our status in developing the 2nd transistor layer above the 1st CMOS layer using TMD materials.
10:00 AM Invited
Mixed-Dimensional Hetero-structures for Advanced Logic and Memory Devices: Deep Jariwala1; 1University of Pennsylvania
The isolation of a growing number of two-dimensional (2D) materials has inspired worldwide efforts to integrate distinct 2D materials into van der Waals (vdW) heterostructures. While a tremendous amount of research activity has occurred in assembling disparate 2D materials into “all-2D” van der Waals heterostructures and making outstanding progress on fundamental studies, practical applications of 2D materials will require a broader integration strategy. Given that any passivated, dangling bond-free surface will interact with another via vdW forces, the vdW heterostructure concept can be extended to include the integration of 2D materials with non-2D electronic materials. In this talk I will focus on mixed-dimensional (2D + nD, where n is 0, 1 or 3) heterostructures. I will present our ongoing and recent work on integration of 2D materials with 3D electronic materials to realize logic switched and memory devices with novel functionality that can potentially augment the utility of Silicon technology.