A team lead by researchers at the Royal Melbourne Institute of Technology (RMIT), Australia, introduced ultrathin beta-tellurite to the 2D semiconducting material family, providing an answer to the decades-long search for a high mobility p-type oxide.<\/p>\n
A new study, published in Nature Electronics, could pave the way to revolutionary, transparent electronics. Such see-through devices could potentially be integrated in glass, in flexible displays, and in smart contact lenses, bringing to life futuristic devices that seem like the product of science fiction.<\/p>\n
For several decades, researchers have sought a new class of electronics based on semiconducting oxides, whose optical transparency could enable fully-transparent electronics. Oxide-based devices could also find use in power electronics and communication technology, reducing the carbon footprint of our utility networks.<\/p>\n
A barrier to oxide devices has been that while many high-performance n-type oxides are known, there is a significant lack of high-quality p-type oxides. But, in 2018, a computational study revealed that beta-tellurite (\u03b2-TeO2) could be an attractive p-type oxide candidate with tellurium’s place in the periodic table indicating it can behave as both a metal and a non-metal, providing its oxide with uniquely useful properties.<\/p>\n
\u201cThis prediction encouraged our group at RMIT University to explore its properties and applications. This new, high-mobility p-type oxide fills a crucial gap in the materials spectrum to enable fast, transparent circuits,\u201d says team leader Dr. Torben Daeneke, who led the collaboration with three Future Low-Energy Electronics Technologies (FLEET) partners at RMIT.<\/p>\n
Dr. Daeneke’s team demonstrated the isolation of beta-tellurite with a specifically developed synthesis technique that relies on liquid metal chemistry. The process is similar to drawing, using a glass rod as a pen and liquid metal as ink.<\/p>\n
While the desirable \u03b2-phase of tellurite grows below 300\u00b0C, pure tellurium has a high melting point, above 500\u00b0C. Selenium was added to design an alloy that has a lower melting point, making the synthesis possible.<\/p>\n
A molten mixture of tellurium (Te) and selenium (Se) was prepared and allowed to roll over a surface. Due to oxygen in the ambient air, the molten droplet naturally forms a thin surface oxide layer of beta-tellurite. As the liquid droplet is rolled over the surface, this oxide layer sticks to it, depositing atomically thin oxide sheets in its way.<\/p>\n
The 1.5 nanometer thick ultrathin sheets with a bandgap of 3.7 eV were highly transparent across the visible spectrum, essentially invisible to the human eye.<\/p>\n
To assess the electronic properties of the developed materials, field-effect transistors were fabricated. The devices showed characteristic p-type switching as well as a high hole mobility (roughly 140 cm2V-1s-1), showing that beta-tellurite is ten to one hundred times faster than existing p-type oxide semiconductors. The excellent on\/off ratio (over 106) also attests the material is suitable for power efficient, fast devices.<\/p>\n
The findings, fast, transparent p-type semiconductors, have the potential to revolutionize transparent electronics while enabling better displays and improved energy-efficient devices, closing a crucial gap in the electronic material library.<\/p>\n
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