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The correlation between the photons emitted by an optically pumped single quantum dot is investigated. The correlation function on a single dot isolated in a mesa shows that only one photon is emitted at a time at the exciton frequency. These quantum states of light can be generated with a high quantum efficiency, with the use of cavity effects: surrounding the dot by a pillar microcavity not only increases significantly the single photon flux but also allows the preparation of single photons all in the same quantum state (same spatial mode and same polarization). © 2002 Published by Elsevier Science B.V.

We present atomic-scale characterization of site-controlled InAs/InP(001) quantum dots grown by metal-organic chemical vapor deposition using nano-area selective area growth. We have developed for this purpose a process combining e-beam lithography, inductively coupled-plasma etching and focused ion beam etching to isolate a few quantum dots. The size, the shape and the composition of the quantum dots are investigated by Scanning Transmission Electron Microscopy. A comparison with the well-known single self-assembled quantum dots highlights the specificities of our growth mode compared to the Stranski–Krastanov growth mode.

We demonstrate the feasibility of a new approach based on the nano selective area growth (nano-SAG), which allows the precise spacial localization, in the nanometer scale, of InAs/InP quantum dots (QDs) grown by low-pressure metal organic vapor-phase epitaxy. By using the hydrogen silsesquioxane-negative resist, we partially pattern the substrate in only one step (e-beam lithography) with dielectric masks containing nano-openings. We demonstrate that the one-step nano-SAG technique leads to the formation of site-controlled InAs/InP QDs with good structural properties, and allows the good control of the growth rate and thus of the QD size into the nano-openings.