MRS Meetings and Events

 

NM07.09.07 2022 MRS Fall Meeting

Controlling the Location and Morphology of 3D Nanostructures During van der Waals Epitaxy

When and Where

Dec 1, 2022
9:45am - 10:15am

Hynes, Level 2, Room 203

Presenter

Co-Author(s)

Frances Ross1

Massachusetts Institute of Technology1

Abstract

Frances Ross1

Massachusetts Institute of Technology1
van der Waals epitaxy enables the integration of 2D and 3D materials, optimally creating well-ordered 2D/3D interfaces with properties suitable for electronic devices. Critical aspects of the deposited 3D material, such as the density and location of nucleation sites and the morphology of epitaxial islands, depend globally on growth and materials parameters but locally on the condition of the initial van der Waals surface. Here we discuss how the 2D surface can be patterned before growing the 3D material so that a spatially inhomogeneous deposit results. We first discuss the importance of the substrate on which the 2D layer is supported. We demonstrate that freestanding regions of graphene show orders of magnitude lower nucleation density for Au, compared to the surrounding supported areas. This phenomenon, which we attribute to the effect of roughness on diffusion parameters, represents a method of patterning the deposited material that does not involve lithography of the top surface of the 2D layer. We next discuss the use of defects and step edges to modify nucleation sites, and consider the use of strain transfer across freestanding regions of the 2D material to control island shape and create stacked self-assembled structures. We finally describe nucleation and morphology control through heterogeneous sites, which may be catalytic nanomaterials or structures that modify surface energy locally. By combining these strategies, we suggest that modification of a 2D layer followed by van der Waals epitaxy presents versatile opportunities to form mixed dimensional structures that combine 3D materials on 2D surfaces.

Keywords

crystallographic structure | epitaxy | self-assembly

Symposium Organizers

Jeehwan Kim, Massachusetts Institute of Technology
Sanghoon Bae, Washington University in Saint Louis
Deep Jariwala, University of Pennsylvania
Kyusang Lee, University of Virginia

Publishing Alliance

MRS publishes with Springer Nature