Scanning near-field infrared micro-spectroscopy on buried InAs quantum dots


Scanning near-field infrared micro-spectroscopy on buried InAs quantum dots

Jacob, R.; Fehrenbacher, M.; Winnerl, S.; Bhattacharyya, J.; Schneider, H.; Helm, M.; von Ribbeck, H.-G.; Eng, L. M.; Atkinson, P.; Rastelli, A.; Schmidt, O. G.

Providing an optical resolution on the nanometer length scale, scanning near-field optical microscopy (SNOM) turned out to be a capable technique to investigate the optical properties of perovskites, buried semiconductors and single quantum dots. Thereby, the line-width of the observed resonances (5 - 8 meV) is significantly smaller than the inhomogeneously broadened line-width of other spectroscopic measurements.
Using a scattering-type-SNOM (s-SNOM) combined with a tunable free-electron laser (FEL) light source we investigated the electronic structure of single InAs quantum dots, capped under a 70 nm thick GaAs layer. Spectroscopic near-field scans clearly identified two inter-sublevel transitions within the quantum dots at 85 meV and 120 meV, contrasting from the surrounding medium. Moreover, spatially scanning the s-SNOM tip at fixed excitation energies allowed mapping the 3D distribution of such buried quantum dots.

Keywords: Spectroscopy on single quantum dots; self-assembled quantum dots; near-field microscopy; intersublevel transitions

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Publ.-Id: 17579