Apr 06, 2016

Researchers at Berkeley Lab have experimentally demonstrated the ability to electrically generate and control valley electrons in transition metal dichalcogenide (TMDC, a 2D semiconductor) .

Berkeley lab TMDC valleytronic schema

The researchers say that this is the first demonstration of electrical excitation and control of valley electrons. TDMCs are considered to be more mature (closer to production) than any other semiconductors that exhibit valleytronic properties.

To create the valleytronics device, a monolayer of TMDC was coupled with a host ferromagnetic semiconductor. Electrical spin injection from the ferromagnetic semiconductor localized the charge carriers to one momentum valley in the TMDC monolayer. The scientists were able to electrically excite and confine the charge carriers in only one of two sets of valleys. This was achieved by manipulating the injected carrier’s spin polarizations, in which the spin and valley are locked together in the TMDC monolayer.

The two sets of valleys emit different circularly polarized light - this can be oserved to confirm the valley electron control.