Shao Electron Microscopy Lab has identified a way to see the hidden three-dimensional organization of ferroelectric materials at nanometer resolution across a full wafer.
You might not think that the electric polarization structure of ferroelectric materials directly concerns you.
But if you’re looking to boost the memory of your smartphone, the sound quality of your earbuds, or the energy-efficiency of your washing machine… Then you already have a stake in the work of Shao Electron Microscopy Lab.
Housed within the USC Core Center of Excellence in Nano Imaging, a research center jointly supported by USC Viterbi and USC Dornsife, the lab develops and applies novel electron microscopy techniques to understand materials and devices at the atomic scale.
A metrology gap in emerging electronics
Metrology, the scientific study of measurement, is a crucial aspect of activating the potential properties of nanomaterials. “We live in a three-dimensional world, but most metrology methods are still based on two-dimensional mapping,” said Yu-Tsun Shao, assistant professor at USC Viterbi’s Mork Family Department of Chemical Engineering & Materials Science.
Presenting their findings in Nature Communications and Advanced Functional Materials, the lab has now identified a way to see the hidden three-dimensional organization of ferroelectric materials at nanometer resolution across a full wafer (an ultra-flat slice of semiconductor material).
This directly tackles a bottleneck in the development of advanced materials. The challenge has been twofold: researchers could neither visualize polarization structures in three dimensions without damaging the sample, nor map those structures across an entire wafer while retaining nanometer-scale resolution.
The DREDI research team: L-R: Amir Avishai, senior scientist at USC CNI; Assistant Professor Yu-Tsun Shao; Ting-Ran Liu, PhD student at Shao Electron Microscopy Lab.
“Existing high-resolution techniques can examine only extremely small regions, often tens of nanometers wide, while wafer-scale inspection tools lack the resolution needed to see the nanoscale domain structures that control device behavior,” said Shao.
“That misses a lot of information at larger scales and creates a barrier to next-generation technologies like quantum communication and advanced photonic devices, where performance depends on structures that span vastly different sizes.”
The new imaging tool, Depth-Resolved Electron Diffraction Imaging (DREDI), is the first technique to address both challenges in a single instrument, enabling non-destructive three-dimensional imaging while simultaneously connecting nanoscale detail to wafer-scale inspection.
From daily devices to next-gen technology
In the case of ferroelectrics, electric polarization can be switched and sustained even after the electric field is removed, allowing the retention of electrical states without relying on continuous power. This unique property makes it possible to build non-volatile memories, highly sensitive sensors, precision actuators, compact capacitors and energy-harvesting devices.
Let’s extrapolate those capabilities into potential technologies. Just imagine a world of self-adjusting buildings enabled by advanced sensors and actuators, optically connected greenhouses monitoring the health of every plant, prosthetic limbs with near-natural tactile feedback…
But why the wait?
When it comes to our smartphones and other daily devices, nanotechnologists have managed to get along by focusing on small sections of a wafer. However, many proposed post-silicon computing technologies depend on controlling tiny ferroelectric domains reliably across entire wafers.
To make the leap from here to there, we first have to cross the metrology gap.
Seeing the bigger picture
“At first, we turned to the scanning electron microscope (SEM) while waiting for the new transmission electron microscope (TEM) to be installed.” Said Shao. “But it turned out that the SEM was not just a substitute. It gave us a new way to image buried polarization structures in three dimensions, and the fact that SEMs are widely available makes the method even more powerful.”
The paper in Nature Communications essentially outlines the novel features of the new imaging method: greater accuracy at larger scales, faster processing, and non-destructive investigation.
Using standard scanning electron microscopes (SEMs) already common in university and industry laboratories, DREDI can image polarization structures from nanometers to millimeters, while also probing beneath the material surface.
“DREDI let us follow the same polar order across length scales that are usually disconnected,” said Ting-Ran Liu, PhD student in the USC Mork Family Department and the first author of the paper. “We could look at nanoscale domain patterns and also how those patterns organize across much larger regions.”
Time is of the essence: the technique can perform measurements more than 1000 times faster than piezoresponse force microscopy, one of the standard methods currently used to image ferroelectric structure.
And – unlike conventional nanoimaging techniques – the process does not require physically slicing the sample apart, enabling non-destructive depth profiling with nanoscale resolution.
DREDI discoveries
The paper in Advanced Functional Materials puts the new tool to use, demonstrating the first ever mapping of polar order continuously across six orders of magnitude.
“For the past 20 years, most studies only looked at these interfaces over tens of nanometers,” said Shao. “By zooming out to millimeter-scale regions of a ferroelectric film, we identified a previously unrecognized type of phase boundary existing at much larger scales.”
Again, this relates to how nanoscale structure impacts material properties; phase boundaries occur where different crystal structures meet inside a material. At those interfaces, competing structural arrangements can produce unusual electrical, optical or mechanical behavior.
Large-area mapping of phase boundaries revealed by DREDI.
The implications are still being explored, but the findings open new questions about whether researchers could eventually engineer these extended phase boundaries into devices with tailored optical, acoustic or electromechanical properties. By combining wafer-scale imaging with nanoscale resolution in a standard electron microscope platform, DREDI could also help to close the gap between laboratory-scale materials research and scalable device manufacturing.
“Now that we’re starting to investigate structures not just at the nanometer scale, but at mesoscopic and millimeter scales, that opens a new dimension for the discovery and activation of new material properties,” said Shao. “Ultimately, that changes the type of devices that can be developed – devices that have yet to be imagined.”
Published on June 12th, 2026
Last updated on June 12th, 2026