Platform Enhances Functional Properties and Affordability of Materials for Next-Gen Devices

Kyusang Lee, assistant professor of electrical and computer engineering and materials science and engineering at UVA, has extended his seminal research in epitaxy—the growth of a crystalline material on a substrate—to semiconductors used in next-generation electronic and photonic devices. Two journals, Nature and Nature Nanotechnology, published papers related to this research in February 2020. 

Lee began this research as a postdoctoral associate in the Department of Mechanical Engineering at the Massachusetts Institute of Technology. Working with mechanical and electrical engineers and materials scientists at MIT, Ohio State and the UAE’s Masdar Institute of Science and Technology, Lee developed a crystalline compound semiconductor growth process that overcame limitations imposed by lattice-matching between two material systems. The editors of Nature published this breakthrough as their April 2017 cover article.

The 2017 paper presented a proof of concept for a new way to grow thin films. The process enables expensive semiconductor film to be copied from underlying substrates through a 2D material—in this case graphene—to the substrate of interest, repeating the layers several times. Because graphene is a very thin and robust material, the ability to re-use graphene-coated substrates generates significant cost savings in the manufacture of non-silicon electronics and photonic devices.

Lee’s enhanced process achieves the same benefits, using compound materials such as gallium nitride or complex-oxide materials such as perovskite as the middle, transport layer, stacking and coupling three-dimensional structures. Compound and complex-oxide materials are 100 to 1,000 times more expensive than silicon; re-using or recycling the materials makes new electro-optical devices more affordable.

Lee’s process entails the fabrication of materials for free-standing semiconductor film, which is not possible using conventional methods. The resulting platform enhances the functional properties of materials for next-generation electronic, spintronic, magnetoelectric, neuromorphic and energy conversion storage devices. The process also minimizes defects to achieve a dramatic improvement in the quality of the material platform that is non-identical with the underlying substrate.

Grants from the National Science Foundation and the U.S. Department of Energy support Lee’s research in thin films and material systems. Lee’s most recent papers are co-authored with co-principal investigators at the Massachusetts Institute of Technology and contributors to a collaborative research effort that involves several universities and research institutes in the United States, China and South Korea.