In a newly published study, a team of researchers at the University of Oxford’s Department of Materials, led by Harish Bhaskaran, Professor of Applied Nanomaterials, describes a groundbreaking approach to taking nanowires. singly from growth substrates and place them on virtually any platform with sub-micrometer accuracy.
This innovative method uses new tools, including polyethylene terephthalate (PET) ultrathin filaments with tapered nanoscale tips that are used to pick up individual nanowires. At this small scale, van der Waals binders (microscopic forces of attraction that occur between atoms and molecules) cause the nanowires to ‘jump’ into contact with the ends. The nanowires are then transferred to a transparent dome-shaped elastic stamp mounted on a slide. The stamp is then flipped upside down and aligned with the device chip, with the nanowire then gently printed onto the surface.
The deposited nanowires show strong adhesive qualities, which remain in place even when the device is immersed in liquid. The team was also able to place nanowires on delicate substrates, such as 50-nanometer ultrathin films, demonstrating the sophistication and versatility of the stamping technique.
In addition, the researchers used this method to fabricate a photomechanical sensor (a device that uses laser light to measure vibrations) that is 20 times more sensitive than existing nanowire-based devices. .
Nanowires, a material with a diameter 1000 times smaller than a human hair and fascinating physical properties, could make huge advances in fields ranging from energy receivers and sensors, to technology. information technology and quantum. In particular, their ultra-small size could allow the development of smaller transistors and miniaturized computer chips. However, a major obstacle to realizing the full potential of nanowires is the inability to precisely position them in devices.
Most electronics manufacturing techniques cannot withstand the conditions required to manufacture nanowires. Therefore, nanowires are usually grown on a separate substrate and then mechanically or chemically transferred into the device. However, in all existing nanowire transfer techniques, nanowires are randomly placed onto the chip surface, which limits their application in commercial devices.
Utku Emre Ali, a DPhil (Department of Materials) student who developed the technique, said: ‘This new pick-and-place assembly process has allowed us to create the first devices in the wire world. nano. We believe it will inexpensively advance nanowire research by allowing users to combine nanowires with existing on-chip platforms, be it electronic or photonics, unlocking properties. physics unattainable so far. Furthermore, the technique can be fully automated, making high-quality nanowire-integrated chip fabrication a real possibility. ‘
Professor Harish Bhaskaran (Department of Materials) added: ‘This technique can be easily extended to larger areas and holds the promise of nanowires for devices made on any substrate and using using any procedure. This is what makes this technique so powerful. ‘
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