Smaller and more compact is the direction in which computer chips are moving. Two-dimensional (2D) materials are considered to have great potential since 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.
The problem is that 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 offer is nullified.
Silicon and silicon oxide are materials with very good electronic properties and for a long time, ever thinner layers of these materials were used to miniaturize electronic components. When the silicon layer is only a few nanometers thick so that it only consists of a few atomic layers, 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 made up only of surfaces and no longer has a bulk, it can have completely different material properties.
Therefore, one has to switch to other materials in order to create ultra-thin electronic components. 2D materials combine excellent electronic properties with minimal thickness; however, they have to be placed on the appropriate substrate and an insulator layer is needed on top of it. The insulator also has to be extremely thin and of extremely good quality.
Researchers analyzed how to solve this problem. Silicon dioxide, which is normally used in industry as an insulator, is not suitable in this case. It has a very disordered surface and many free, unsaturated bonds that interfere with the electronic properties in the 2D material. A well-ordered structure exists in fluorides — a special class of crystals. A transistor prototype with a calcium fluoride insulator has already provided convincing data and other materials are still being analyzed.
For more information, contact Prof. Tibor Grasser at