DNA assembly of 3D nanomaterials; Mott insulator transistor; faster wireless data speeds.
Scientists from Brookhaven National Laboratory, Columbia University, and Stony Brook University developed a method that uses DNA to instruct molecules to organize themselves into targeted 3D patterns and produce a wide variety of designed metallic and semiconductor 3D nanostructures.
“We have been using DNA to program nanoscale materials for more than a decade,” said corresponding author Oleg Gang, a professor of chemical engineering and of applied physics and materials science at Columbia Engineering, in a release. “Now, by building on previous achievements, we have developed a method for converting these DNA-based structures into many types of functional inorganic 3D nano-architectures, and this opens tremendous opportunities for 3D nanoscale manufacturing.”
Researchers program strands of DNA to “direct” the self-assembly process towards molecular arrangements that give rise to properties such as electrical conductivity, photosensitivity, and magnetism, which can then be scaled up to functional materials.
The team used the method to grow silica on a DNA lattice, which helped to create a robust structure. They then used vapor-phase infiltration and liquid-phase infiltration, which bonds a precursor chemical in vapor or liquid form to a nanoscale lattice, to produce a variety of 3D metallic structures.
Scientists used a new, universal method to create a variety of 3D metallic and semiconductor nanostructures, including this structure revealed by an electron microscope. The scale bar represents one micrometer. The superimposed graphics convey that the researchers combined multiple techniques to layer silicon dioxide, then alumina-doped zinc oxide, and finally platinum on top of a DNA “scaffolding.” This complex structure represents new possibilities for advanced manufacturing at small scales. (Credit: Brookhaven National Laboratory)
“Stacking these techniques showed much more depth of control than has ever been accomplished before,” said Aaron Michelson, a postdoctoral researcher at Brookhaven’s Center for Functional Nanomaterials, in a release. “Whatever vapors are available as precursors for vapor-phase infiltration can be coupled with various metal salts compatible with liquid-phase infiltration to create more complex structures. For example, we were able to combine platinum, aluminum, and zinc on top of one nanostructure.”
They were also able to add on semiconducting metal oxides, such as zinc oxide, to an insulating nanostructure, providing it with electrical conductivity and photoluminescent properties. [1]
Researchers from the University of Nebraska-Lincoln, Brookhaven National Laboratory, University of the Basque Country, and NYU Shanghai propose a way to make transistors out of Mott insulators.
The researchers were able to direct the Mott transition from insulator to metal and back again by topping a Mott insulator with a gate insulator made of a ferroelectric material and using a voltage to flip the ferroelectric material’s polarization. A third layer beneath the Mott channel that allows charges to migrate from the Mott down to it improved control over the insulator-metal transition with an on-off ratio of 385.
Additionally, the researchers claim that the Mott-ferroelectric pairing is more energy-efficient than other non-volatile but magnetism-based memory, including MRAM.
“We can have very high-performance devices, retaining many manufacturing processes of conventional semiconductors and overcoming some fundamental limitations of them,” said Xia Hong, professor of physics at the University of Nebraska-Lincoln, in a release. “I think it’s ready. It’s really competitive with other non-volatile memory technologies.” [2]
Researchers from Osaka University and IMRA America suggest a way to increase wireless data transmission speeds by reducing the noise in the system using lasers.
Future 6G transmitters and receivers are expected to use the sub-terahertz band, which extends from 100 GHz to 300 GHz, using an approach called “multi-level signal modulation” to further increase the data transmission rate. However, this approach is highly sensitive to noise at the upper end of the frequency range.
“This problem has limited 300-GHz communications so far,” said Keisuke Maekawa of Osaka University in a statement. “However, we found that at high frequencies, a signal generator based on a photonic device had much less phase noise than a conventional electrical signal generator.”
The team used a stimulated Brillouin scattering laser, which employs interactions between sound and light waves, to generate a precise signal. They then set up a 300 GHz-band wireless communication system that employs the laser-based signal generator in both the transmitter and receiver. The system also used on-line digital signal processing (DSP) to demodulate the signals in the receiver and increase the data rate.
“Our team achieved a single-channel transmission rate of 240 gigabits per second,” said Tadao Nagatsuma, a professor at Osaka University, in a release. “This is the highest transmission rate obtained so far in the world using on-line DSP.” The researchers expect that with multiplexing techniques and more sensitive receivers, the data rate can be increased to 1 terabit per second. [3]
[1] Aaron Michelson et al., Three-dimensional nanoscale metal, metal oxide, and semiconductor frameworks through DNA-programmable assembly and templating. Sci. Adv. 10, eadl0604 (2024). https://doi.org/10.1126/sciadv.adl0604
[2] Hao, Y., Chen, X., Zhang, L. et al. Record high room temperature resistance switching in ferroelectric-gated Mott transistors unlocked by interfacial charge engineering. Nat Commun 14, 8247 (2023). https://doi.org/10.1038/s41467-023-44036-x
[3] Keisuke Maekawa, Tomoya Nakashita, Toki Yoshioka, Takashi Hori, Antoine Rolland, Tadao Nagatsuma, Single-channel 240-Gbit/s sub-THz wireless communications using ultra-low phase noise receiver, IEICE Electronics Express, Article ID 20.20230584, Advance online publication December 25, 2023, Online ISSN 1349-2543, https://doi.org/10.1587/elex.20.20230584
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