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HomeNanotechnologyResearchers add a 'twist' to classical materials design

Researchers add a ‘twist’ to classical materials design

Jan 24, 2024

(Nanowerk Information) Researchers with the Division of Power’s SLAC Nationwide Accelerator Laboratory, Stanford College and the DOE’s Lawrence Berkeley Nationwide Laboratory (LBNL) grew a twisted multilayer crystal construction for the primary time and measured the construction’s key properties. The twisted construction may assist researchers develop next-generation supplies for photo voltaic cells, quantum computer systems, lasers and different units. “This construction is one thing that we have now not seen earlier than – it was an enormous shock to me,” stated Yi Cui, a professor at Stanford and SLAC and paper co-author. “A brand new quantum digital property may seem inside this three-layer twisted construction in future experiments.” text CAPTION

Including layers, with a twist

The crystals the staff designed prolonged the idea of epitaxy, a phenomenon that happens when one kind of crystal materials grows on high of one other materials in an ordered manner – sort of like rising a neat garden on high of soil, however on the atomic stage. Understanding epitaxial development has been essential to the event of many industries for greater than 50 years, notably the semiconductor trade. Certainly, epitaxy is a part of most of the digital units that we use at this time, from cell telephones to computer systems to photo voltaic panels, permitting electrical energy to circulation, and never circulation, by way of them. To this point, epitaxy analysis has targeted on rising one layer of fabric onto one other, and the 2 supplies have the identical crystal orientation on the interface. This strategy has been profitable for many years in lots of functions, resembling transistors, light-emitting diodes, lasers and quantum units. However to seek out new supplies that carry out even higher for extra demanding wants, like quantum computing, researchers are trying to find different epitaxial designs – ones that is likely to be extra advanced, but higher performing, therefore the “twisted epitaxy” idea demonstrated on this research. Of their experiment, detailed in Science (“Twisted epitaxy of gold nanodisks grown between twisted substrate layers of molybdenum disulfide”), researchers added a layer of gold between two sheets of a conventional semiconducting materials, molybdenum disulfide (MoS2). As a result of the highest and backside sheets had been oriented in another way, the gold atoms couldn’t align with each concurrently, which allowed the Au construction to twist, stated Yi Cui, Professor Cui’s graduate pupil in supplies science and engineering at Stanford and co-author of the paper. “With solely a backside MoS2 layer, the gold is blissful to align with it, so no twist occurs,” stated Cui, the graduate pupil. “However with two twisted MoS2 sheets, the gold isn’t positive to align with the highest or backside layer. We managed to assist the gold clear up its confusion and found a relationship between the orientation of Au and the twist angle of bilayer MoS2.”

Zapping gold nanodiscs

To check the gold layer intimately, the researcher staff from the Stanford Institute for Supplies and Power Sciences (SIMES) and LBNL heated a pattern of the entire construction to 500 levels Celsius. Then they despatched a stream of electrons by way of the pattern utilizing a method referred to as transmission electron microscopy (TEM), which revealed the morphology, orientation and pressure of the gold nanodiscs after annealing on the completely different temperatures. Measuring these properties of the gold nanodiscs was a essential first step towards understanding how the brand new construction may very well be designed for actual world functions sooner or later. “With out this research, we might not know if twisting an epitaxial layer of metallic on high of a semiconductor was even potential,” stated Cui, the graduate pupil. “Measuring the entire three-layer construction with electron microscopy confirmed that it was not solely potential, but additionally that the brand new construction may very well be managed in thrilling methods.” Subsequent, researchers wish to additional research the optical properties of the gold nanodiscs utilizing TEM and study if their design alters bodily properties like band construction of Au. Additionally they wish to prolong this idea to attempt to construct three-layer buildings with different semiconductor supplies and different metals. “We’re starting to discover whether or not solely this mix of supplies permits this or if it occurs extra broadly,” stated Bob Sinclair, the Charles M. Pigott Professor in Stanford’s college of Supplies Science and Engineering and paper co-author. “This discovery is opening a complete new collection of experiments that we will attempt. We may very well be on our approach to discovering model new materials properties that we may exploit.”


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