Super and Semiconductors are highlights of the year with application challenges – summaries

The Covid-19 pandemic, like everything else, completely changed the list of major scientific achievements in 2020.

In 2020, the three-dimensional structures of proteins were finally revealed, three missions were sent to Mars and others to look for material on the moon and the asteroid Ryugu, and we have made important advances in strategies to treat various diseases, including HIV, achieved. However, it became difficult to compete with vaccines, which were developed in a tenth the time normally used and with all the knowledge of a virus and disease that was completely unknown a year ago.

Despite all these perturbations, there are no traditional lists of this kind – like those published in Nature and Science magazines – in which the production of the first superconducting material at room temperature is not recorded, even if it is not and is nicknamed “Discovery” wearing. Science of the Year ”.

Like a zoonotic pandemic, it wasn’t exactly surprising to receive the new material. Other lists from the end of 2019 on what to expect from science in 2020 registered the expectation. In this case, the shift in focus to Covid-19 does not appear to have affected work in the region.

The scientists combined hydrogen, carbon and sulfur and observed superconductivity at temperatures up to about 14 ° C. Superconductivity was understood to be the exclusive property of very low temperatures from 1911 when it was discovered until 1986, the year the Ascent began until the first temperatures above 0 ° C were reported in October of this year.

Aside from being an incremental and expected breakthrough built over decades, there’s another reason the performance seems a little tepid (no pun intended!): The material was obtained with a print that was more than 2.5 million times higher than that of the environment we live in, made between the claws of a kind of diamond clamp. Hence, it is still a long way from the fantastic applications envisioned for room temperature superconductors, from medical devices and ultrafast maglev trains to extreme energy efficiency in general, as the resistance to current flow in these materials is lacking, thus reducing energy losses.

From the general lists, but winner of a special competition sponsored by Physics World Magazine, another material received in 2020 shares with the room temperature superconductor not only the challenges to application, but also the nickname of the Holy Grail (in this case the microelectronic industry or better optoelectronics).

It is a silicon nanowire that is synthesized with a hexagonal crystal structure (pattern of the spatial order of the atoms in the material) and not with a diamond-like structure, as the material normally presents itself.

Silicon is the basis of the entire microcomputer industry because of its electronic (semiconductor) properties, coupled with the fact that it is abundant and cheap. However, an important operational limit is close at hand. The growth in the processing power of the chips implies an increase in energy consumption and also in the heat generated by the resistance of the material in a scenario that can only be overcome by the integration of photonics – the transmission of information by light, i.e. photons instead of electrons – to electronics .

And the king of electronics performs poorly when it comes to its optical properties. Some semiconductors emit light when exposed to an electrical current, as is the case with LEDs. However, this is not the case with conventional silicon due to an inherent property of the material (called an indirect gap or indirect band structure). So far, the way to incorporate light has been through the integration of other materials in silicon chips, which is possible, but difficult and expensive.

This obstacle can be overcome with the new material, with potential applications also in telecommunications and chemical sensors. However, there is still a need to produce hexagonal silicon on a flat surface instead of the nanowire, which the researchers believe is only a matter of time.

Moving from one year to the next brings the feeling of having a new time to overcome challenges, solve problems, and achieve the goals set on the eve of January 1st. By the end of 2020, fighting the pandemic will undoubtedly be a priority for the whole world, and fortunately for a large part of the scientific community. For many materials scientists and engineers, however, making superconductors at ambient temperature and pressure in the vicinity, as well as silicon-based lasers, should be on the list.

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