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Ohio State engineers and CEMAS essential to research featured on Nature cover
The Ohio State University’s capacity and expertise in high-end microscopy has come into focus on the cover of Nature. Scholars at Ohio State’s Center for Electronic Microscopy and Analysis (CEMAS) teamed up with Massachusetts Institute of Technology engineers to develop a new technique that used graphene as a “copy machine” to produce cheaper semiconductor wafers.
The new method uses single-atom-thin sheets of graphite to transfer intricate crystalline patterns from an underlying semiconductor wafer to a top layer of identical material.
A team of experts led by Materials Science and Engineering Professor Jinwoo Hwang at CEMAS provided the direct confirmation of remote epitaxy at the graphene interface. Epitaxy describes the process of depositing one single crystalline material onto another single crystal material. The research appears in the April 20 edition of Nature.
“The new technology enables epitaxial growth of single crystal semiconductor films remotely through a single sheet of graphene,” said Hwang. “This can lead to new technological breakthroughs, including defect-free epitaxial growth of semiconductor thin films, and recycling and reuse of expensive substrates that have been difficult in the past.”
In 2016, annual global semiconductor sales reached their highest-ever point, at $339 billion worldwide. In that same year, the semiconductor industry spent about $7.2 billion worldwide on wafers that serve as the substrates for microelectronics components, which can be turned into transistors, light-emitting diodes, and other electronic and photonic devices.
Hwang said that the phenomenon that they refer to as “remote epitaxy” in the paper is a completely new discovery. He and graduate research assistant Jared Johnson examined the detailed atomic structure of the interface, which consists of two semiconductors sandwiching the graphene layer, to understand the detailed mechanism.
In an epitaxial growth, the deposited film is fixed in a crystallographic orientation with respect to the substrate crystal, which acts as a seed material. If the orientation of the film is random with respect to the substrate, epitaxy hasn’t taken place.
“Cross-sectional STEM (scanning transmission electron microscopy) characterization is pretty much the only way to get the detailed atomic structure at the interface,” Hwang said. “It requires a high-end instrument, such as the one we have in CEMAS. Careful sample preparation and imaging using low electron dose were also very important because the graphene layer can be easily damaged by the electron beam.”
CEMAS Director David McComb said this is an example of how the center’s world-class capabilities are being used to learn about new phenomena that have the potential to change the world.
Engineers at the Masdar Institute of Science and Technology also collaborated on the research.
For a more detailed description of the research: MIT's news release.