Utrecht researchers open new way for low-power energy harvesters

Publication in Nature Electronics

Because of the huge growth of wireless technologies and portable devices, one of the main energy challenges is to develop microscale devices that are able to harvest ambient energy, such as electromagnetic radiation, and convert it into usable electrical energy. The physical process central to the harvesting of electromagnetic energy is called rectification: the conversion from an oscillating electromagnetic field to a direct current (DC). Rectification has wide-ranging applications in various fields, such as biology, climatology, meteorology, and astronomy

Energy harvesters of electromagnetic energy are in great demand in particular in the microwave and terahertz frequency energy. Because of this, rectification is currently explored not only in conventional semiconducting junctions but also in new non-centrosymmetric crystals that intrinsically show non-linear electrical and optical responses.

Peculiar quantum property

In a publication in Nature Electronics, a research team including Utrecht physicist Carmine Ortix has shown that strong non-linear electric responses can arise in bilayer graphene – a material consisting of two single layers of carbon atoms – using the capability of elastic deformations (strain) to modify the electronic properties on demand.

In order to produce appropriate strain patterns, the researchers have realized a new architecture consisting of bilayer graphene deposited on a lithographically corrugated hexagonal boron nitride substrate. This engineered strain endows the material with a very peculiar quantum property – the newly discovered Berry curvature dipole – that in turn grants the material a very large non-linear electric response.

All together these results identify a new path to obtain non-linear second-order responses producing current rectification and open a new-way to low-power energy harvesters.

Publication

Hall effects in artificially corrugated bilayer graphene without breaking time-reversal symmetry
Sheng-Chin Ho, Ching-Hao Chang, Yu-Chiang Hsieh, Shun-Tsung Lo, Botsz Huang, Thi-Hai-Yen Vu, Carmine Ortix*, Tse-Ming Chen
Nature Electronics, 16 February, DOI 10.1038/s41928-021-00537-5

* researcher affiliated with Utrecht University