SKM 2023 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 42: Quantum dots: Growth
HL 42.1: Vortrag
Donnerstag, 30. März 2023, 15:00–15:15, POT 151
Cone-shell quantum structures with tunable wave functions — •Christian Heyn, Ahmed Alshaikh, Kristian Deneke, and Robert Blick — Center for Hybrid Nanostructures (CHyN), University of Hamburg
We discuss the tailoring of the wave functions (WF) in strain-free GaAs quantum structures (QS) fabricated using self-assembled local droplet etching (LDE) during molecular beam epitaxy (MBE). Here, Al droplets are deposited on an AlGaAs surface and drill nanoholes with tunable shape and size. Subsequently, the holes are filled with GaAs to form strain-free QS. Dependent on the process parameters, the QS have the shape of a cone or of a cone-shell. In particular the low-density (about 1x107 cm−2) cone-shell QS (CSQS) demonstrate sharp exitonic lines with linewidth down to 25 µeV, a precise control of the emission wavelength from 680…810 nm by the nanohole filling level, a neutral exiton fine-structure splitting below 5 µeV, and nearly perfect single photon emission. To tune the WF in CSQS, a vertical electric field is applied which causes a strong charge-carrier separation. The resulting Stark shift is measured using micro-photoluminescence (PL). In combination with simulation results the optical data allow the determination of the QS size and shape. In addition, simulations indicate the transformation of either the electron or the hole WF into a quantum ring. As a further consequence of the field-induced charge-carrier separation, simulations of the exciton-recombination lifetimes predict a variability from nanoseconds up to milliseconds. This suggests CSQS for applications in the field of light storage