2017 Symposium on Functional Nanomaterials: Emerging Nanomaterials and Nanotechnology: 2D Nanomaterials for Nanoelectronics
Sponsored by: TMS Functional Materials Division, TMS: Nanomaterials Committee
Program Organizers: Jiyoung Kim, University of Texas; Stephen McDonnell, University of Virginia; Chang-Yong Nam, Brookhaven National Laboratory; V. U. Unnikrishnan, The University of Alabama; Nitin Chopra, The University of Alabama

Monday 2:00 PM
February 27, 2017
Room: Pacific 26
Location: Marriott Marquis Hotel

Session Chair: Stephen McDonnell, University of Virginia; Myung Mo Sung, HanYang University

2:00 PM  Invited
Graphene for Alternative Digital Logic Applications: Byoung Hun Lee1; 1Gwangju Institute of Science and Technology
    There is a skepticism on the possibility of the applications of graphene in digital logic technology due to the problems originated from zero bandgap. After the extensive pursuits of bandgap generation in a graphene which turn out to degrade the device performance, the skepticism appears to be spreading. In this talk, how the graphene can be used in digital logic applications even without a bandgap and what are the challenges in that approach will be discussed. Then, a few examples of novel graphene devices will be presented.

2:30 PM  Invited
Two-dimensional Materials for Next Generations of Electronic Devices: Saptarshi Das1; 1Pennsylvania State University
    Two dimensional (2D) materials are receiving considerable attention from various scientific and engineering disciplines due to their exceptional properties, which not only provide a platform to investigate exciting physical phenomena but also promise solutions to the many technological challenges. MoS2, WSe2, Black Phosphorus, Graphene and many more belong to this class of materials which find their application in flexible electronics, self-powered electronics, optoelectronics, neural electronics as well as digital electronics. A major challenge towards the commercialization of 2D materials is the large area, scalable and controllable growth of mono-layers in a cost effective way. In this context, chemical vapor deposition, liquid phase exfoliation and electrochemical synthesis approaches are showing a lot of promise. This talk will provide a holistic understanding of 2D materials starting from large area synthesis to device fabrication to different electronic applications.

3:00 PM  Invited
Two-dimensional Nanosheets for Electron Device Applications: Seongil Im1; 1Yonsei University
    Two-dimensional (2D) semiconductor materials have attracted much attention from many researchers owing to their interesting physical properties and potentials for future nanoscale electronics. Here, we adopted p-WSe2 and n-MoS2 nanosheets separately for the channels of bottom gate-patterned FETs, to fabricate 2D transition metal dichalcogenide (TMD)-based hetero-CMOS inverter on a same glass substrate by a direct dry transfer technique. Our hetero-CMOS inverters with electrically-isolated FETs demonstrate novel and superior device performances of a maximum voltage gain as ~27, subnanowatt power consumption, almost ideal noise margin approaching, and ~800 μs for switching delay. Moreover, our glass-substrate CMOS device nicely performed digital logic (NOT, OR, and AND) and push-pull circuits for organic light emitting diode switching, directly displaying the prospective of practical applications. Furthermore, 2D-CMOS studies show n-MoS2 and p-MoTe2 couple for faster switching of less than 60 us. In the presentation, our n-MoS2/p-WSe2 and n-MoS2/p-MoTe2 PN diodes are also introduced.

3:30 PM Break

3:50 PM  Invited
Realizing Large-scale 2-D Materials: Properties and Applications: Joshua Robinson1; 1The Pennsylvania State University
    The last decade has seen nearly exponential growth in the science and technology of two-dimensional materials. Beyond graphene, there is a huge variety of layered materials that range in properties from insulating to superconducting. Furthermore, heterogeneous stacking of 2D materials also allows for additional “dimensionality” for band structure engineering. In this talk, I will discuss recent breakthroughs in two-dimensional atomic layer synthesis and properties, including novel 2D heterostructures and novel 2D nitrides. Our recent works include development of an understanding of substrate impact on 2D layer growth and properties, doping of 2D materials with magentic elements, selective area synthesis of 2D materials, and the first demonstration of 2D gallium nitride (2D-GaN). Our work and the work of our collaborators has lead to a better understanding of how substrate not only impacts 2D crystal quality, but also doping efficiency in 2D materials, and stabalization of nitrides at their quantum limit.

4:20 PM  Invited
Nucleation of ALD on Graphene and Transition Metal Dichalcogenide (TMDs): Iljo Kwak1; Jun Hong Park1; Bernd Fruhberger1; Andrew Kummel1; 1University of California, San Diego
    Two-Dimensional semiconductors offer great opportunity for high performance devices because their naturally chemically and electronically passive surfaces allow carrier confinement in a nearly defect free material. However, the chemically passive surfaces make deposition of sub 5nm gates oxides challenging since the surface are inert and chemical functionalization is likely to change the chemical structure or induce doping. An alternative approach is deposition of 1-2 nanometer Al2Ox particles which molecularly chemisorb and nucleate ALD on inert surfaces without perturbing the electronic structure. Uniform and defect-free Al2O3 films were grown on HOPG and MoS2 by ALD at low temperature (50 oC). Capacitance-voltage measurements of Al2O3 films grown at 50 oC using 50 ALD cycles showed an areal capacitance 1.17 μF/cm2 with very small frequency dispersion on HOPG and MoS2, consistent with the absence of induction cycles and formation of a high quality interface.

4:50 PM  Invited
Using Ions to Control Transport in Two-dimensional Materials for Electronics: Susan Fullerton1; Ke Xu1; Jierui Liang1; 1University of Pittsburgh
    Two-dimensional (2D) materials are molecularly thin, layered materials held together by van der Waals forces. Because charge moves freely in the 2D plane, these materials have potential application in electronics; however, conventional doping strategies have not been developed for 2D materials. An alternative approach is to use electrolyte gating. Under an applied gate voltage, ions in the electrolyte create an electrostatic double layer (EDL) at the interface between the electrolyte and the semiconductor; the EDL can induce sheet carrier densities on the order of 1014 cm-2 for both electrons and holes – more than one order of magnitude larger than conventional gating techniques. I will describe our work using electrolytes to dope transistors and memory devices based on graphene and transition metal dichalcogenides (TMDs). Our group has developed a 2D electrolyte for use in memory devices based on 2D crystals, and the first device characteristics will be presented.

5:20 PM  
Novel In Situ Electrical Characterization of the Dielectric Deposition Process on 2-D Transition Metal Dichalcogenides: Antonio Lucero1; Lanxia Cheng1; Joy Lee1; Jaebeom Lee1; Xin Meng1; Arul Ravichandran1; Young-Chul Byun1; Jaegil Lee1; Jiyoung Kim1; 1University of Texas at Dallas
    Two-dimensional transition metal dichalcogenide (TMD) materials such as molybdenum disulfide and tungsten diselenide exhibit a number of characteristics which make them suitable for use in low power electronic devices. However, the chemical inertness of the TMD surface presents challenges when growing thin gate dielectrics with atomic layer deposition (ALD), and typically requires the use of plasma or ozone surface functionalization. These processes can alter the electrical properties of the TMD, though the mechanism is not well understood. In this work the surface functionalization and dielectric deposition process is performed in an ultra-high vacuum cluster tool which allows ALD, plasma enhanced ALD, and electrical characterization to be performed in situ. In order to better understand the effects of the dielectric deposition process, electrical measurements are performed on exfoliated MoS2 backgate devices after surface functionalization and individual ALD cycles. The mechanism of these ALD induced changes will be discussed in this work.