A group of researchers from Florida State University (FSU) and Rensselaer Polytechnic Institute has demonstrated that high-quality single-crystalline films can be grown even when separated from their substrate by several nanometers. This finding challenges previous scientific assumptions about the limits of remote epitaxy.
“This was one of those neat moments in science where you do something and then have to figure out how it happened and why it happened,” said Florida State University Professor of Physics Hanwei Gao. “This research has a lot of long-term implications for next-generation electronics and other materials, but it also was a classic case of scientists trying to solve a mystery.”
The team used a process called remote epitaxy, which allows crystalline films to grow on substrates through an ultrathin buffer layer. This technique makes it possible for the films to be transferred and combined with various important materials in technology development.
Previously, scientists believed that the remote interaction needed for epitaxy could only work over distances less than 1 nanometer. The new findings, published in Nature, show that this process can occur across amorphous carbon layers as thick as 7 nanometers—about 20 layers of graphene.
The collaboration began due to Gao’s experience working with Yan Xin, a scientist at the National High Magnetic Field Laboratory who specializes in electron microscopy. Xin used advanced microscopes to analyze films created by Gao’s team, allowing them to observe internal structures at atomic resolution. This confirmed that the observed film growth was indeed caused by remote epitaxy rather than undetected defects or holes.
According to the researchers, this discovery suggests that remote epitaxy can be engineered by using substrate defects intentionally. This could lead to new approaches for designing advanced electronic and optoelectronic devices.
The project was led by Hanwei Gao from FSU along with Jian Shi and Yunfeng Shi from Rensselaer Polytechnic Institute. It involved contributions from multiple institutions and received support from the U.S. National Science Foundation, the NYSTAR Focus Center at Rensselaer, and the National High Magnetic Field Laboratory.
