Research Sculpts Photons and Electrons to Improve Sensing and Imaging Capabilities

Avik Ghosh, University of Virginia professor of electrical and computer engineering and physics, has joined a multi-university initiative to understand and model the physics of promising semiconductor materials used in infrared opto-electronic systems.

Viktor A. Podolskiy, professor of physics at the University of Massachusetts Lowell, leads the team. Ghosh is a co-principal investigator. Seth Bank and Daniel Wasserman, professors of electrical and computer engineering at the University of Texas-Austin, and Evgenii Narimanov, professor of electrical and computer engineering at Purdue University, are also co-principal investigators.

The team members’ research will enable future devices and systems for a wide range of scientific research and investigation such as intracellular imaging, and open new doors to quantum communication. Their research also will boost existing remote sensing and night vision capabilities, and better serve internet of things and 5G communication that require sensing within a large bandwidth with very little power.

A grant awarded by the National Science Foundation’s Designing Materials to Revolutionize and Engineer Our Future program supports the team’s research. This is the primary program by which NSF participates in the Materials Genome Initiative for Global Competitiveness, a national, decade-long investment to accelerate advanced materials discovery and deployment.

Avik Ghosh, professor of electrical and computer engineering, discusses progress in quantum materials and nanomagnetism with Virginia Nano Computing Group members Shafat Shahnawaz (left) and Sheikh Ahmed (right).

“If we are going to sustain innovation in communications and information processing, we must better understand and learn how to control both electronic and optical properties of these new semiconductor materials,” Ghosh said.

Opto-electronic devices detect and convert light signals, or photons, into electric current, or electrons. The problem is that the wavelengths of photons and electrons are naturally mismatched. Infra-red photons are very long wavelength and fast, whereas electron waves are much smaller and slower. The team seeks to confine the photons through the material engineering of so-called hyperbolic metamaterials, and to control electron wavelength through the strategic placement of miniature energy band-gaps in digital alloy superlattices. 

“Our research will dramatically enhance the alignment of photons and electrons, squeezing photons and stretching out electrons,” Ghosh said. The resulting increase in photon-electron interaction — meaning photons are more efficiently coupled with electrons — will boost the electronic device’s sensitivity to non-visible light.

UMass Lowell and Purdue lead computational and theoretical research to decrease the size of photons and create waveguides to control light. UT-Austin will be responsible for experimental parts of the program, namely materials growth, postprocessing and characterization.

Banks’ research group has perfected the fabrication of thin films to control the thickness of each atomic layer to avoid strain and defects while Wasserman’s team has expertise in controlling concentration of free electrons within the layers.

Ghosh’s Virginia nano-computing research group will develop computational models and conduct simulations to establish the material design principles for UT-Austin’s digital alloys, such as how electronic band structures and current flow impact electron-photon interaction.

The team anticipates collaboration with the Air Force Research Lab to use the materials they develop in a new generation of practical devices

“The DMREF funding enables the development of fundamentally new material platform, as well as exploration of the frontiers of light-matter interaction within these materials. In the process of research, the team will train a next-generation workforce of scientists and engineers,” Podolskiy said.

This research builds on Ghosh’s modeling and measurement of digital alloys used to fabricate avalanche photodiodes. Bank and Joe Campbell, Lucien Carr III Professor of electrical and computer engineering at UVA, join Ghosh in this effort, supported by a grant from the National Science Foundation’s Electronics, Photonics and Magnetic Devices Program.

This is the second Designing Materials to Revolutionize and Engineer Our Future grant Ghosh has earned. In 2012, Ghosh’s Virginia nano computing group earned a joint award with William Butler, professor of physics and astronomy at the University of Alabama, to design a magnetic, intermetallic compound with enhanced magnetic properties.

Ghosh and Butler’s discoveries in this material system — referred to as Heusler alloys — played a central role in a subsequent Defense Advanced Research Projects Agency award to Ghosh’s research group to develop and test a new paradigm for magnetic storage in electronic devices. Ghosh and teammates at UVA, New York University and the Massachusetts Institute of Technology are creating ideal materials to engineer high density, ultrafast, all electronic solid-state memory devices.