Cryogenic Investments to Transform Triangle Region Nanoscale Research

Many of tomorrow’s biggest advances will rely on incredibly small features created with tight precision. Microprocessor components are already measured in nanometers, and metamaterials must be designed with features smaller than the wavelengths of light or sound they seek to manipulate, which is on the order of hundreds of nanometers for the visible spectrum.

Advanced devices and materials created to promote healing and store energy are also proving to require nanoscale manufacturing capabilities. Many of these developing technologies, however, are also more delicate than traditional semiconductors and require enhanced stability to withstand being poked, prodded and machined. To ensure these materials are not damaged or destroyed by the tools used to examine and shape them, researchers are increasingly turning to sub-freezing-cold cryogenics.

Duke Engineering is making a substantial investment in cutting-edge cryogenic nanoscale fabrication and microscopy facilities that will transform the portfolios of researchers working on materials-dependent projects in fields ranging from biotechnology to energy and sustainability.

With machines and capabilities unique not just to Duke, but to the entire Research Triangle region of North Carolina, this multimillion-dollar investment into cryogenic tools will be a boon to academic and industrial pursuits alike.

“These high-resolution cryomicroscopy capabilities developed at Duke are crucial to understanding complex hard-soft material interfaces, such as those found in novel dielectric nanocomposites or advanced energy storage materials,” said Cate Brinson, chair of the mechanical engineering and materials science department. “These instruments will inspire interdisciplinary teams across materials science, computation, physics, chemistry and data science to explore and design new materials and interfaces at the atomic level for applications in energy, sustainability and quantum information science.”

The first machine being purchased is a Thermo Fischer Scientific Cryogenic Helios 5 CX DualBeam for Materials Science (C-Helios 5 CX). One of the most advanced instruments of its kind, the C-Helios 5 CX features both electron microscopy and ion beam fabrication capabilities. The former will allow researchers to examine materials at the atomic level while the latter will allow them to create devices and designs with sub-millimeter precision.

While the instrument already boasts several electron beam and ion beam improvements that make it simultaneously extremely sensitive and gentle on the materials being used, it also features a cryogenic stage to flash freeze and stabilize specimens. For example, a cryogenic stage is especially critical for many energy storage materials, which are sensitive to ion and electron beams and can only be imaged and sectioned at cooled temperatures.

The C-Helios 5 CX is funded by a $1.5 million grant from the National Science Foundation secured by Natalia Litchinitser, professor of electrical and computer engineering, physics, and mechanical engineering and materials science at Duke.

The C-Helios 5 CX will enable nanofabrication and structural characterization of a plethora of photonic nanostructures from optical meta-surfaces and meta-lenses integrated on a cross-section of optical fibers used in telecommunication or medical endoscopy to near-field optical scanning imaging systems enabling a subwavelength resolution in a nondestructive optical setup.

In particular, this tool will facilitate a project funded by Intel aimed at designing and prototyping a hyperbolic metamaterial-based system for imaging with subwavelength resolution.

It will also impact an ongoing collaboration with Gleb Finkelstein, professor of electrical and computer engineering, and of physics at Duke, focused on nonlinear wavelength conversion in van der Waals materials hybridized with all-dielectric metasurfaces; as well as Jie Liu, professor of chemistry at Duke, focused on 3D photonic structure-based catalyst support for enabling solar ammonia synthesis under concentrated sunlight.

The C-Helios 5 CX is a huge upgrade in research and development facilities in and of itself, but it is also instrumental in preparing specimens for a second major investment coming to Duke’s campus: a JEOL- JEM-ARM300F2 GRAND ARM™2 scanning transmission electron microscope (STEM). This particular instrument is configured to excel in atomic-scale imaging and spectroscopy of beam-sensitive materials, including ion conductors used in batteries, soft materials for fuel cells and biological applications, and liquid-solid interfaces prevalent in energy storage, energy conversion, and medical systems.

STEM scans a focused electron probe approximately half an angstrom in diameter—roughly equivalent to the size of a single hydrogen atom—on the object under examination. By analyzing the exiting electrons after their interaction with the object, it can generate atom-by-atom maps of the specimen.

The combination of a cryogenic stage, a fast-scanning system and direct electron detectors will provide groundbreaking insights into delicate materials. It will also enhance our understanding of quantum materials, which exhibit unique properties at cryogenic temperatures, particularly in the context of spintronic applications.

One of Duke Engineering’s newest faculty members, Miaofang Chi, is a leading expert in developing innovative strategies to continually enhance cryo-STEM capabilities and applying these techniques to study a wide range of energy and quantum materials.

“Many materials used in energy conversion and storage systems, such as polymers, liquid electrolytes and fast ion conductors, are susceptible to electron beam damage. Therefore, it’s essential to cool them down to mitigate electron beam irradiation for proper study. This instrument will be an empowering tool for our collaborative research with professor Olivier Delaire on high-performance composite cathodes for lithium and sodium metal batteries,” Chi said.

This work is expected to foster new investigations across various interdisciplinary research topics, including:

• Energy materials, where colleagues David Mitzi, Delaire and Jun Liu are actively engaged
• Nanophotonics
• Novel engineered materials, which Litchinitser is leading
• Biomedical research

The instrument’s specific configuration is geared toward the atomic-to-nano scale analysis of energy materials. Distinctive features, such as high-speed scanning and in situ cryogenic cooling, will be exceptionally advantageous for comprehending material behaviors and degradation mechanisms within energy and sustainability applications, encompassing batteries, fuel cells, and more.

Moreover, this instrument is anticipated to catalyze collaborations with industries in the field of energy and sustainability within central North Carolina’s booming tech corridor.

The cryo-STEM is funded by Duke and will be installed in the fall 2024. Both machines will be housed within the Shared Materials Instrumentation Facility (SMiF), an interdisciplinary, shared resource open to researchers across Duke—as well as to users from other universities, government laboratories and industry.

Used for both research and educational purposes, the SMiF currently has about 500 users, of which 60% are from Duke, 25% are from other universities and non-profit organizations, and 15% are from industry.

The 11,000-square-foot facility includes 4,000 square feet of class 100 and class 1000 clean rooms and over 2,600 square feet of specialized laboratory space for characterization equipment.

SMIF features cutting-edge technology in electron-beam lithography, photolithography, metal and dielectric deposition, and dielectric etching capability, along with material and device characterization tools. And now it will soon feature a cryogenic-focused ion beam and scanning transmission electron microscopy as well.