Friday, April 18, 2014

Growth and stacking 2D materials MoS2, WSe2, and hBN on epitaxial graphene by CVD

Researchers at Penn State's Center for 2-Dimensional and Layered Materials and the University of Texas at Dallas have shown the ability to grow high quality, single-layer materials one on top of the other using CVD (chemical vapor deposition). Furthermore, they have demonstrated growth and stacking 2D materials MoS2, WSe2, and hBN on epitaxial graphene by CVD.  

 
The stacking of two-dimensional layered materials: MoS2, WSe2, and hBN on epitaxial graphene (Picture from graphical abstract:ACS Nano, DOI: 10.1021/nn5003858)
 
 
Read more at Nanowerk: Making new materials an atomic layer at a time or in the publication below.
Direct Synthesis of van der Waals Solids

Yu-Chuan Lin, Ning Lu, Nestor Perea-Lopez, Jie Li, Zhong Lin, Xin Peng, Chia Hui Lee, Ce Sun, Lazaro Calderin, Paul N. Browning, Michael S. Bresnehan, Moon J. Kim, Theresa S. Mayer, Mauricio Terrones , and Joshua A. Robinson

ACS Nano, Article ASAP, DOI: 10.1021/nn5003858, Publication Date (Web): March 18, 2014

Abstract:
The stacking of two-dimensional layered materials, such as semiconducting transition metal dichalcogenides (TMDs), insulating hexagonal boron nitride (hBN), and semimetallic graphene, has been theorized to produce tunable electronic and optoelectronic properties. Here we demonstrate the direct growth of MoS2, WSe2, and hBN on epitaxial graphene to form large-area van der Waals heterostructures. We reveal that the properties of the underlying graphene dictate properties of the heterostructures, where strain, wrinkling, and defects on the surface of graphene act as nucleation centers for lateral growth of the overlayer. Additionally, we show that the direct synthesis of TMDs on epitaxial graphene exhibits atomically sharp interfaces. Finally, we demonstrate that direct growth of MoS2 on epitaxial graphene can lead to a 103 improvement in photoresponse compared to MoS2 alone.


A photosensor fabricated on the MoS2/graphene heterostructure. (Image: Yu-Chuan Lin, Penn State)