Dartmouth engineering professor Jifeng Liu is part of a group of researchers recently selected for a Department of Defense (DoD) Multidisciplinary University Research Initiative (MURI) award. The team hopes to develop a new generation of infrared imaging sensors made of a powerful semiconducting material that could significantly improve night-vision systems for self-driving vehicles as well as military applications.

"I am excited to serve on this MURI team and push forward new imaging technologies beyond visible light through fundamental materials research,” said Liu, a co-principal investigator on the grant.

A "firework" of germanium tin crystallization. Photo by Lisa Je & Alejandra Cuervo Covian.

The team has identified a group of silicon-germanium-tin alloys that are compatible with existing silicon sensors and can help imaging technologies such as cameras and military equipment function in extreme low-light conditions beyond the visible spectrum. Liu will be examining the material’s optical properties and stability at the nanoscale and hopes to identify a way to integrate the material with silicon and grow it defect-free.

"This material system is in the very early stages of development," said Liu. "We hope to use our research to understand its fundamentals and break the barriers in material growth and device integration."

In 2013, Liu received a National Science Foundation CAREER Award on the related topic of "Low-Temperature Growth of High Crystallinity GeSn on Amorphous Materials for Advanced Optoelectronics" which investigates new technology for cost-effective, high-efficiency tandem solar cells as well as three-dimensional photonic circuits on future generations of silicon microchips.

“My previous research paved a path to crystallize this material on all kinds of substrates,” added Liu, “and it facilitates integration with silicon-based image sensors in this project.”

In addition to lead researchers from the University of Arkansas at Fayetteville, Liu will be working with scholars from Arizona State University, University of Massachusetts-Boston, and George Washington University, as well as two Dartmouth engineering PhD candidates, research scientist Xiaoxin Wang, and Eric Fossum, the Krehbiel Professor for Emerging Technologies who is serving as a collaborator. The team is hoping to improve upon current infrared imaging technologies which are limited by a complex and expensive manufacturing process, low production yield, high toxicity, and poor uniformity.

This year, the DoD selected 24 MURI proposals from nearly 300. Liu’s team was awarded $7.5 million for phase one spanning three years and an optional two-year extension. The group met for the first time on October 18th to begin their work.

MURI awards fund basic research spanning multiple scientific disciplines to facilitate growth in newly emerging technologies and address the DoD’s unique problem sets, according to a DoD announcement of the grants.

"The challenges we face today are highly complex in nature and do not fall in line with a single discipline," said Mitch Nikolich, DoD director of Defense Research and Engineering for Research and Technology, in the announcement. "MURIs acknowledge these complexities by supporting teams whose members have diverse sets of expertise as well as creative and different approaches to tackling problems."