Stretched graph changes E-properties

pte20210629018 Research / development, technology / digitization

Scientists from Basel pave the way for the development of new types of electronic components

Component on the rack: graph changes properties (Photo: unibas.ch)

Basel (pte018 / 06/29/2021 / 12:30) – The electrical properties of graphene can be changed in a targeted manner by uniformly stretching the material, as researchers from the University of Basel http://unibas.ch have found out. According to the experts, this paves the way for the development of new types of electronic components.

“Sandwich” on the rack

In order to research the properties of the versatile carbon material under strain, the Basel scientists have developed a kind of stretching board with which they can stretch the wafer-thin graphene layer in a controlled manner and at the same time measure its electrical properties. They first made a “sandwich” consisting of a layer of graphene between two layers of boron nitride. The component provided with electrical contacts was applied to a flexible substrate.

The Swiss researchers then used a wedge to apply pressure to the middle of the sandwich from below. “We use it to bend the component in a controlled manner and thereby lengthen the entire graphene layer,” says first author Lujun Wang, describing the procedure. The effect: “By stretching the graphene, we were able to specifically change the distance between the carbon atoms and thus their binding energy,” adds Wang’s colleague Andreas Baumgartner, who supervised the experiment.

Measurements at 269 degrees Celsius

The researchers initially calibrated the elongation of the graph using optical methods. Then, using electrical transport measurements, they investigated how the deformation of graphene changes the electronic energies. These measurements were made at minus 269 degrees Celsius so that the change in energy was even visible. “The distance between the atomic nuclei directly influences the properties of the electron states in graphene. With uniform expansion, only the electron velocities and the energy can change. The energy change is essentially the theoretically predicted ‘scalar potential’, which we have now been able to demonstrate experimentally”, concluded Baumgartner.

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