2022 User Research Highlights
Remote Epitaxy of 3D functional semiconductors and oxides using Graphene as the Interface layer

Project Summary: Remote epitaxy has drawn attention as it offers epitaxy of functional materials that can be released from the substrates with atomic precision, thus enabling production and heterointegration of flexible, transferrable, and stackable freestanding single-crystalline membranes. In this highlight, 2DCC and PARADIM team up to work with the inventor of remote epitaxy, Prof. Kim (MIT), to unveil the respective roles and impacts of the substrate material, graphene, substrate–graphene interface, and epitaxial material for electrostatic coupling of these materials, which governs cohesive ordering and can lead to single-crystal epitaxy in the overlying film. We show that simply coating a graphene layer on wafers does not guarantee successful implementation of remote epitaxy, since atomically precise control of the graphene-coated interface is required and provides key considerations for maximizing the remote electrostatic interaction between the substrate and adatoms. The general rule of thumb discovered here enables expanding 3D material libraries that can be stacked in freestanding form. This work is published in ACS Nano 2021, 15, 6, 10587–10596.

2DCC Role: The 2DCC provided epitaxial graphene substrates for remote epitaxy of Ge, GaAs, GaN, BaTiO3.

PARADIM Role: Synthesis of BaTiO3 films by remote epitaxy on substrates onto which the graphene from 2DCC had been transferred.

What Has Been Achieved: Deconvoluting the impact of processing on remote epitaxy of 3D materials using graphene as the interface layer.

Importance of the Achievement: This work provides the first understanding and impact of graphene layer transfer and 2D/3D interface properties on remote epitaxy.  It provides an important how-to guide for researchers interested in remote epitaxy regarding the importance of the graphene layer and how it is prepared.

Unique Feature(s) of the MIP that Enabled this Achievement: large area epitaxial graphene (2DCC) and synthesis of complex oxides (PARADIM)

(If Applicable) Publication: ACS Nano 2021, 15, 6, 10587–10596

This work is primarily supported by the Defense Advanced Research Projects Agency Young Faculty Award (Award No. 029584-00001) and by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Solar Energy Technologies Office (award no. DE-EE0008558). The team at MIT also acknowledges support from the Air Force Research Laboratory (FA9453-18-2-0017 and FA9453-21-C0717) and from the Defense Advanced Research Projects Agency (DARPA) (Award No. 027049-00001, W. Carters and J. Gimlett). C.D. and J.A.R acknowledge the Penn State 2D Crystal Consortium (2DCC)-Materials Innovation Platform (2DCC-MIP) under NSF cooperative agreement DMR1539916. The work at Cornell University is supported by the National Science Foundation (Platform for the Accelerated Realization, Analysis and Discovery of Interface Materials (PARADIM)) under Cooperative Agreement No. DMR1539918.