Nat. Commun. 7, 12978 (2016)

The extension of information technologies to the quantum realm has motivated recent efforts towards the development of optoelectronic devices that are able to generate single photons with controlled quantum correlation properties. In view of possible applications, the dimensions of these devices should be scalable to the nanoscale, while the stimulus required to trigger single-photon generation should be electrical. However, devices simultaneously satisfying these requirements are rare.

Now, Mete Atatüre and colleagues at the University of Cambridge in the UK and the National Institute for Materials Science in Japan report an electrically driven single-photon generator based on stacked 2D materials. Here, electrons are injected from graphene to p-doped WSe2 or WS2, where positive and negative charges recombine radiatively. A boron nitride layer acts as a barrier against this process, and biasing the device electrically leads to an increased tunnelling probability for the injected charges. Remarkably, the single-photon emission is associated with spatially localized regions and can be switched on and off by tuning the intensity of the tunnelling current.

The reported phenomenon is effective at low temperatures, but suffers from a spatially homogeneous background emission with no appreciable quantum correlation. Still, these results offer exciting prospects for scalability and on-chip integration of single-photon emitters.