Industry Demands for Miniaturisation
Miniaturisation, of course, is integral to modern usersâ increasing need for smaller, lighter devices. However, given our current rate of technological progress, the question now arises about the extent to which devices can be further miniaturised. In fact, Mooreâs Lawâs proponent, Gordan Moore himself, has also felt the need to refer back to his own school of thought: âWeâre very close to the atomic limitation nowâ, the retired engineer has stated in reference to computer chips.
In fact, as the TU Wien news page explains, we already have so-called â2Dâ materials that can have a thickness of just one atom. (While this makes the term â2D materialsâ technically misleading, weâll continue to use it in inverted commas, rather than its more accurate synonym, âsingle-layer materialsâ.) But while manufacturing one-atom-thick materials is indeed possible, the TU Wien researchers maintain that the resultant microelectronics âcan only be used effectively if â¦ combined with suitable material systemsâ.
As discussed shortlyâand detailed further in TU Wienâs Nature Communications paperâspecial insulating crystals are a crucial example of such material systems.
The Limitations of Traditional Approaches to Miniaturisation
The researchers, based in TU Wienâs Faculty of Electrical Engineering, point out that silicon-based semiconductors (given the strength of their electronic properties) were initially the answer to the industryâs increasing interests in component miniaturisation.
Now, however, with components increasingly being designed at the nanometre scale, the industry is seeing a cap on the electronic potential of silicon-based layers: âThese worked well for a long time,â says Professor Tibor Grasser from TU Wienâs Institute of Microelectronics, âbut at some point, we reach a natural limitâ. TU Wien staff attribute this limit to the problematic electronic properties that come from components with only a few atomic layers.
A graphic atomic model of Vienna University of Technologyâs material of interest: a calcium fluoride crystalline insulator, which is believed to be ideal for component miniaturisation. Image Credit: TU Wien.
TU Wienâs Solution: Introduce Thin Insulators
The TU Wien researchers have proposed that the limitations of â2Dâ materialsâ electronic properties can be addressed by having the ideal substrate and insulator layer.
As Professor Grasser explains: âAs it turns out, â¦ 2D materials are only the first half of the story. The materials have to be placed on the appropriate substrate, and an insulator layer is also needed on top of itâ.
But while insulator layers have in fact always been implemented within â2Dâ materials, TU Wienâs research reflects that the traditional insulator solution, SiOâ (silicon dioxide) is not robust enough to accommodate the requisite flow of electrons in modern miniaturised electronics. Grasser and his colleague Yury Illarionov attribute this to SiOââs âvery disordered surface and many free, unsaturated bondsâ.
Ultimately, TU Wienâs solution is to instead rely on a special class of crystals known as fluorides. The scientists explain that some of the promising crystalline insulator materials are ionic crystals, particularly calcium fluoride (CaFâ) (an atomic model of which is pictured in the middle of the above image). The researchers write in Nature Materials that the ideal materials such as CaFâ have âsurfaces â¦ [that] are chemically inert and free of dangling bondsâ.
The Upshot of Improved Insulation Layers
While the researchers praise the industryâs increasing interests in microelectronics, they maintain that their research at TU Wien reflects the need for a bigger industry focus on resistor layers. To undervalue such resistors, says Grasser, would be âlike driving a Ferrari on muddy ground and wondering why you donât set a speed recordâ.
Whatâs more, the researchers believe that the benefits are not just applicable to semiconductors and other technologies relevant to microelectronics manufacturing: the R&D points to consumer benefits, too.
Conclude the Technische UniversitÃ¤t Wien researchers in their Nature Materials paper: âWe are confident that further development of this research topic will sooner or later enable 2D electronics for commercial applicationsâ.