Journal of Nanomedicine & Nanotechnology

Controlled growth of graphene, carbon nanotubes and transition metal dichalcogenides

6^th Global Experts Meeting on Nanomaterials and Nanotechnology

April 21-23, 2016 Valencia, Spain

Eui-Hyeok Yang

Stevens Institute of Technology, USA

Keynote: J Nanomed Nanotechnol

Abstract:

Initially motivated by work with graphene, the broad class of two dimensional (2D) materials has generated enormous interest in the research community because of its potential for use in electronics, photonic devices, and other applications. Semiconducting transition metal dichalcogenides (TMDs) have found been researched for fundamentals as well as applications including optoelectronics. This is due to their direct bandgaps in the visible, high absorption relative to their thicknesses, ultrafast carrier separation with other 2D materials, and the new fields of spintronics and valleytronics. For these applications, TMDs are frequently patterned post-growth or post-exfoliation even though this is known to compromise device performance. In order to avoid contamination, various techniques such as �??all-dry�?� material transfer and Cu and BN encapsulation have been developed which are time consuming manual processes. Here we develop a direct growth process to enable localized, patterned, single crystalline or large-scale polycrystalline monolayers of MoS2, WS2, WSe2 and MoSe2 along with their heterostructures by the chemical vapor deposition method. Our new growth method permits the growth of TMDs on the �??contacted�?? areas only, enabling fabrication of 2D layers in controlled shapes without lithography at desired locations on the substrate. Our growth-patterning techniques are a possible route towards realizing devices with fewer processing steps without introducing device-degrading levels of contamination. If the technique could be developed to be highly reliable and high fidelity it could have a large impact on the future research and commercializability of TMD-based devices. We also demonstrate an approach toward controlled growth of carbon nanotubes (CNTs) atop graphene substrates, where the reaction equilibrium between the source hydrocarbon decomposition and carbon saturation into/precipitation from the catalyst nanoparticles shifts toward CNT growth, rather than graphene consumption.

Biography :

Eui-Hyeok Yang is a Professor of the Mechanical Engineering Department at Stevens Institute of Technology. He was a Senior Member of the Engineering Staff at NASA's Jet Propulsion Laboratory. He received a number of awards, including the prestigious Lew Allen Award for Excellence at JPL in 2003 in recognition of his excellence in advancing the use of MEMS-based actuators for NASA's space applications. He is an Associate Editor and/or Editorial Board of several journals including the IEEE Sensors Journal. As Principal Investigator, he has been responsible for obtaining extremely competitive research funding from several federal agencies including NSF, AFOSR, US Army, NRO, NASA and DARPA (including 6 NSF and 3 AFOSR grants, and 5 NASA and 3 NRO contracts) with the total amount exceeding $7M.

Email: eyang@stevens.edu