Ultrathin semiconductors electrically connected to superconductors — ScienceDaily

Maria J. Danford

For the first time, University of Basel researchers have equipped an ultrathin semiconductor with superconducting contacts. These very slender products with novel digital and optical homes could pave the way for formerly unimagined programs. Merged with superconductors, they are predicted to give increase to new quantum phenomena and uncover use in quantum technological innovation.

No matter if in smartphones, televisions or building technological innovation, semiconductors perform a central position in electronics and as a result in our everyday lives. In distinction to metals, it is probable to change their electrical conductivity by making use of a voltage and for this reason to switch the existing movement on and off.

With a check out to upcoming programs in electronics and quantum technological innovation, researchers are focusing on the growth of new elements that consist of a one layer (monolayer) of a semiconducting substance. Some normally transpiring products with semiconducting homes attribute monolayers of this kind, stacked to kind a 3-dimensional crystal. In the laboratory, researchers can different these layers — which are no thicker than a one molecule — and use them to make digital elements.

New homes and phenomena

These ultrathin semiconductors assure to supply distinctive characteristics that are or else pretty difficult to control, these types of as the use of electrical fields to influence the magnetic times of the electrons. In addition, elaborate quantum mechanical phenomena acquire area in these semiconducting monolayers that might have programs in quantum technological innovation.

Researchers around the globe are investigating how these slender semiconductors can be stacked to kind new synthetic products, known as van der Waals heterostructures. Having said that, until now, they have not succeeded in combining these types of a monolayer with superconducting contacts in get to dig further into the homes and peculiarities of the new products.

Superconducting contacts

A staff of physicists, led by Dr. Andreas Baumgartner in the exploration group of Professor Christian Schönenberger at the Swiss Nanoscience Institute and the Office of Physics of the University of Basel, has now fitted a monolayer of the semiconductor molybdenum disulfide with superconducting contacts for the first time.

The purpose why this mixture of semiconductor and superconductor is so appealing is that the professionals anticipate elements of this kind to exhibit new homes and physical phenomena. “In a superconductor, the electrons arrange on their own into pairs, like associates in a dance — with weird and excellent consequences, these types of as the movement of the electrical existing without a resistance,” describes Baumgartner, the undertaking manager of the analyze. “In the semiconductor molybdenum disulfide, on the other hand, the electrons execute a completely diverse dance, a bizarre solo regime that also incorporates their magnetic times. Now we would like to uncover out which new and unique dances the electrons concur upon if we combine these products.”

Suited for use as a system

The electrical measurements at the very low temperatures essential for superconductivity — just earlier mentioned complete zero (-273.15°C) — present plainly the results induced by the superconductor for case in point, at selected energies, one electrons are no extended allowed. Moreover, the researchers observed indications of a sturdy coupling concerning the semiconductor layer and the superconductor.

“Robust coupling is a crucial ingredient in the new and enjoyable physical phenomena that we anticipate to see in these types of van der Waals heterostructures, but were by no means ready to reveal,” says Mehdi Ramezani, lead writer of the analyze.

“And, of system, we usually hope for new programs in electronics and quantum technological innovation,” says Baumgartner. “In theory, the vertical contacts we’ve designed for the semiconductor layers can be used to a significant range of semiconductors. Our measurements present that these hybrid monolayer semiconductor elements are in fact probable -potentially even with other, a lot more unique get in touch with products that would pave the way for further more insights,” he adds.

Elaborate fabrication method

The fabrication of the new component in a form of sandwich manufactured of diverse products necessitates a significant range of diverse techniques. In just about every action, it is significant to stay clear of contaminations, as they severely impair the transportation of electrical rates.

To safeguard the semiconductor, the researchers pack a monolayer of molybdenum disulfide concerning two slender layers of boron nitride, via which they have formerly etched the contacts vertically applying electron-beam lithography and ion etching. They then deposit a slender layer of molybdenum rhenium as a get in touch with substance — a substance that retains its superconducting homes even in the existence of sturdy magnetic fields.

Doing the job underneath a protective nitrogen environment in a glove box, the researchers stack the boron nitride layer on to the molybdenum disulfide layer and combine the underside with a further more layer of boron nitride as perfectly as a layer of graphene for electrical control. The researchers then area this elaborate van der Waals heterostructure on top rated of a silicon/silicon-dioxide wafer.

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