New materials for extra thin computer chips

Date:
July 13, 2020
Source:
Vienna University of Technology
Summary:
In order to create more compact electronic devices, new materials
are being used - especially 2D-materials, which only consist of
a single atomic layer. This, however, is only half the story:
Every electronic device consists of multiple materials. So the
ultra-thin semiconductors have to be paired with ultra-thin
insulators. Scientists have now found out how to do this.



FULL STORY ==========================================================================
Ever smaller and ever more compact -- this is the direction in which
computer chips are developing, driven by industry. This is why so-called
2D materials are considered to be the great hope: they are as thin as
a material can possibly be, in extreme cases they consist of only one
single layer of atoms.

This makes it possible to produce novel electronic components with tiny dimensions, high speed and optimal efficiency.


========================================================================== However, there is one problem: electronic components always consist of
more than one material. 2D materials can only be used effectively if
they can be combined with suitable material systems -- such as special insulating crystals.

If this is not considered, the advantage that 2D materials are supposed
to offer is nullified. A team from the Faculty of Electrical Engineering
at the TU Wien (Vienna) is now presenting these findings in the journal
Nature Communications.

Reaching the End of the Line on the Atomic Scale "The semiconductor
industry today uses silicon and silicon oxide," says Prof.

Tibor Grasser from the Institute of Microelectronics at the TU
Wien. "These are materials with very good electronic properties. For
a long time, ever thinner layers of these materials were used to
miniaturize electronic components. This worked well for a long time --
but at some point we reach a natural limit." When the silicon layer is
only a few nanometers thick, so that it only consists of a few atomic
layers, then the electronic properties of the material deteriorate very significantly. "The surface of a material behaves differently from the
bulk of the material -- and if the entire object is practically only made
up of surfaces and no longer has a bulk at all, it can have completely different material properties." Therefore, one has to switch to other materials in order to create ultra-thin electronic components. And
this is where the so-called 2D materials come into play: they combine
excellent electronic properties with minimal thickness.

Thin layers need Thin Insulators "As it turns out, however, these 2D
materials are only the first half of the story," says Tibor Grasser. "The materials have to be placed on the appropriate substrate, and an insulator layer is also needed on top of it -- and this insulator also hast to be extremely thin and of extremely good quality, otherwise you have gained
nothing from the 2D materials. It's like driving a Ferrari on muddy ground
and wondering why you don't set a speed record." A team at the TU Wien
around Tibor Grasser and Yury Illarionov has therefore analysed how to
solve this problem. "Silicon dioxide, which is normally used in industry
as an insulator, is not suitable in this case," says Tibor Grasser.

"It has a very disordered surface and many free, unsaturated bonds that interfere with the electronic properties in the 2D material." It is
better to look for a well-ordered structure: The team has already achieved excellent results with special crystals containing fluorine atoms. A
transistor prototype with a calcium fluoride insulator has already
provided convincing data, and other materials are still being analysed.

"New 2D materials are currently being discovered. That's nice, but
with our results we want to show that this alone is not enough," says
Tibor Grasser.

"These new electrically conductive 2D materials must also be combined with
new types of insulators. Only then can we really succeed in producing
a new generation of efficient and powerful electronic components in
miniature format."

========================================================================== Story Source: Materials provided
by Vienna_University_of_Technology. Original written by Florian
Aigner. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Yury Yu. Illarionov, Theresia Knobloch, Markus Jech, Mario Lanza,
Deji
Akinwande, Mikhail I. Vexler, Thomas Mueller, Max C. Lemme,
Gianluca Fiori, Frank Schwierz, Tibor Grasser. Insulators for 2D
nanoelectronics: the gap to bridge. Nature Communications, 2020;
11 (1) DOI: 10.1038/ s41467-020-16640-8 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200713120018.htm

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