Semiconducting 2-D alloys could be key to overcoming the technical limitations of modern electronics. Although 2-D Si–Ge alloys would have interesting properties for this purpose, they were only predicted theoretically. Now, scientists from the Japan Advanced Institute of Science and Technology have realized the first experimental demonstration. They have also shown that the Si to Ge ratio can be adjusted to fine-tune the electronic properties of the alloys, paving the way for novel applications.
Alloys—materials composed of a combination of different elements or compounds—have played a crucial role in the technological development of humans since the Bronze Age. Today, alloying materials with similar structures and compatible elements is essential because it enables us to fine-tune the properties of the final alloy to match our needs.
The versatility provided by alloying naturally extends to the field of electronics. Semiconductor alloys are an area of active research because new materials will be needed to redesign the building blocks of electronic devices (transistors); in this regard, two-dimensional (2-D) semiconductor alloys are seen as a promising option to go past the technical limitations of modern electronics. Unfortunately, graphene, the carbon-based poster child for 2-D materials, does not lend itself easily to alloying, which leaves it out of the equation.
However, there is an attractive alternative: silicene. This material is composed entirely of silicon (Si) atoms arranged in a 2-D honeycomb-like structure reminiscent of graphene. If the properties of silicene could be tuned as needed, the field of 2-D silicon-based nanoelectronics would take off. Although alloying silicene with germanium (Ge) was theoretically predicted to yield stable 2-D structures with properties tunable by the Si to Ge ratio, this was never realized in practice.
The implications of this study are important for multiple reasons. First, the ultimate thinness and flexibility of 2-D materials is appealing for many applications because it means they could be more easily integrated in devices for daily life. Second, the results could pave the way to a breakthrough in electronics. Co-author of the study, Professor Yukiko Yamada-Takamura from JAIST, explains, “Semiconducting 2-D materials made of silicon and germanium with atomically-precise thickness could further decrease the dimensions of the elemental bricks of electronic devices. This would represent a technological milestone for silicon-based nanotechnologies.”
Overall, this study showcases but a few of the advantages of alloying as a way to produce materials with more desirable properties than those made from a single element or compound. Let us hope semiconducting 2-D alloys are further refined so that they can take the spotlight in next-generation electronic devices.
