Single Photon Emission from Monolayer Islands

High-magnification image of the In(Ga)N single atomic monolayer, used as a new single photon emitter. (Source: X. Sun et al. / CAS)

Non-classical light sources such as single photon emitters are essential devices for the realization of future optical quantum techno­logies including optical quantum computing and quantum key distribution. To date several strategies, including single atoms, quantum dots (QDs), single molecules, and point defects, have been used to explore the development of single photon emitters. Although great strides have been made in the develop­ment of solid-state single photon emitters, including high purity and indistin­guishability from QDs, and high emission rates from both defects and QDs, each technology has its own drawbacks. Therefore, basic research into the development of single photon emitters using new materials and techniques is crucial.

Now, a team of scientists from State Key Labora­tory for Meso­scopic Physics and Frontiers Science Center for Nano-opto­electronics, School of Physics, Peking University, China, and Institute of Industrial Science, The Univer­sity of Tokyo, Japan have developed a novel type of quantum emitter formed from spatially separated monolayer islands of InGaN sandwiched in a GaN matrix.

They first grew a planar structure of InGaN monolayer islands using molecular beam epitaxy, and then patterned the sample into pillars using nano­imprint lithography and inductively-coupled plasma reactive-ion etching. Detailed optical analysis of the emission properties of the isolated monolayer islands showed that the main emission line could be spec­trally filtered to act as a bright, and fast single photon emitter at a wave­length of ~ 400 nm, with a high degree of photo­stability.

“III-nitride materials were chosen for this study because they are expected to offer several advantages for the development of future devices, including a wide tunability in emission wave­length, compa­tibility with silicon substrates for growth, and support from a worldwide industrial infra­structure for device fabri­cation due to their extended use in modern day opto­electronics and power device applications”, say the researchers.

The team also suggest that the next step in the research is to work towards higher emission purity, and that future developments – possibly using other materials – could lead to the reali­zation of emitters operating at wavelengths compatible with conven­tional fiberoptic systems. (Source: LPA-CAS)

Reference: X. Sun et al.: Single-photon emission from isolated monolayer islands of InGaN, Light: Sci. & App. 9, 159 (2020); DOI: 10.1038/s41377-020-00393-6

Link: Frontiers Science Center for Nano-Optoelectronics, School of Physics, Peking University, Beijing, China

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