Growing patterned diamond; thermal constraint for ferroelectrics; improved microLEDs.
Researchers from Rice University developed a bottom-up microwave plasma chemical vapor deposition method for growing patterned diamond surfaces that could help decrease operating temperatures in electronics by 23 degrees Celsius.
The team used two techniques for controlling seed crystal placement. Photolithography was used for small, detailed patterns. To scale up to a 2-inch wafer, the team laminated a commercially available film onto the wafer, then cut the desired pattern with a laser. The unwanted sections were peeled away, and diamond seeds were applied across the surface. Peeling off the remaining film left a clean, patterned template for diamond growth, obtained without harsh chemicals or complex processing.
The microwave plasma CVD method was then used to build solid diamond layer by layer. “This plasma breaks down carbon-heavy gases mixed with hydrogen, and the carbon atoms rain down and settle onto your substrate,” said Xiang Zhang, assistant research professor of materials science and nanoengineering at Rice, in a press release. By adjusting seeding density, the researchers could influence crystal size and structure within a single pattern. As proof of concept, the study tested silicon and gallium nitride substrates, but the method could also be applied to other base layers.
“This work demonstrates wafer-scale, selective diamond growth compatible with heterogeneous integration, enabling high-performance thermal management at device-relevant temperatures and layouts,” added Yuji Zhao, a professor of electrical and computer engineering at Rice. [1]
Researchers from Sungkyunkwan University designed a thermal constraining technique that uses heat to control the internal structure of hafnium oxide-based ferroelectric in-memory compute transistors.
The team designed the electrode surrounding the semiconductor material so that, as it cools and slightly contracts, it applies a compressive force to the hafnium oxide inside. The physical force generated by heat aligns the atoms into a crystal structure suitable for memory operation.
“The key point of this research is that we overcame the limitations of next-generation semiconductors through physical design based on thermal force, rather than chemical modification,” said Taesung Kim, a professor in the School of Mechanical Engineering at SKKU. “If this technology is commercialized, AI could operate more intelligently and efficiently in devices where power consumption is important, such as autonomous vehicles and smartphones.”
Devices fabricated using the method remained stable over a trillion operations and achieved an accuracy of 97.2% when used for image recognition tasks. [2]
Researchers from UC Santa Barbara designed a microLED that improves both efficiency and beam directionality, potentially making them a replacement for lasers in data center communications.
“The big thing with lasers is that they start having thermal issues at relatively low temperatures,” said Roark Chao, a doctoral student at UC Santa Barbara, in a statement. “MicroLEDs can be driven much hotter without needing complex cooling. That means less replacement, less cost and more flexibility in data centers.”
By laterally enclosing the emitting region with distributed Bragg reflectors, the researchers achieved roughly 20% higher optical output through air-side emission, more than 130% higher output through the substrate side, and about 30% reduced beam divergence compared with reference devices. Additionally, the design showed roughly 35% higher electrical efficiency. [3]
[1] X. Zhang, C. Chang, Q. Zhu, et al. Scalable selective-area diamond growth for thermal management applications, Applied Physics Letters (2026). https://dx.doi.org/10.1063/5.0319930
[2] G. Kim, H, Seok, S. Son, et al. Thermal Expansion-Engineered Ferroelectric Transistor Arrays for Scalable Edge AI Computing. ACS Nano 2026 20 (5), 4057-4067. https://dx.doi.org/10.1021/acsnano.5c14095
[3] R. Chao, S. Gee, A. M. Quevedo, et al. Enhanced emission efficiency and directionality in InGaN/GaN microLEDs laterally enclosed by distributed Bragg reflectors. Opt. Express 34, 2037-2046 (2026) https://dx.doi.org/10.1364/oe.583145
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