Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2014)
    Thin Films Monday Sessions
       Session TF-MoM

Invited Paper TF-MoM1
Growth Kinetics, Structure, and Properties of 2D Layered Materials

Monday, December 8, 2014, 8:40 am, Room Makai

Session: Self-Organized and Nanostructured Thin Films
Presenter: Suneel Kodambaka, University of California, Los Angeles
Correspondent: Click to Email
Two-dimensional (2D) layered materials owing to a wide range of properties (e.g., graphene is metallic, h-BN is insulating, and MoS2 is semiconducting) have attracted immense attention over the past decade for a variety of optoelectronic and nanoelectronic applications. Recent efforts have focused on vertical integration of 2D layers of dissimilar materials (e.g., graphene/h-BN and graphene/MoS2). In these heterostructures, due to relatively weak van der Waals interactions, orientational registry between the layers is not expected and is often difficult to control. This talk will focus on the effect of interlayer orientation on the electronic structure of the resulting heterostructures. Using a combination of in situ low-energy electron microscopy (LEEM) and density functional theory (DFT) calculations, we investigated the electronic properties of graphene/Pd(111). From the LEEM images we determined the graphene growth kinetics and measured graphene work function as a function of orientation and layer thickness. Recently, we extended our DFT calculations to study the electronic structures of h-BN/Ni(111) and graphene/MoS2 heterostructured layers. We found that hBN can chemisorb or physisorb on Ni(111), with metallic or insulating properties, respectively and these properties are not altered when graphene is placed atop hBN. For graphene on MoS2, we found that rotating graphene layer by 30o with respect to MoS2 changes the MoS2 band gap from 1.68 eV direct to 1.56 eV indirect. We attribute the observed orientation-dependent bandgap to the variation in the S-S interplanar distance with the MoS2-graphene interlayer orientation.