Research

Research focus

  • Epitaxial growth of nanostructures on various substrates using MBE systems.
  • Development of single photon sources in the telecom wavelength range
  • Development of quantum dot emission in the telecom range for spin storage
  • Integration of single InAs/GaAs core-shell quantum dots in silicon
  • Realization of deterministic optical elements
  • Fabrication and investigation of microresonator structures (e.g. photonic crystals)
  • Exploration of 2D materials
  • Studies on structural properties of self-assembled quantum dots
  • Studies of light-matter interactions on the nanoscale of solid-state quantum systems
  • Spectroscopy of immobilized molecules and integration into photonics chip

Research projects

InP-based quantum dots:

(a) µ-PL spectrum from single InP-based quantum dot (QD). The inset shows the 2x2 µm2 2D AFM image of low density QDs. (b) Single-photon emission at telecom wavelengths from single InP-based QDs (in cooperation with Uni. Stuttgart). (c) Coherent properties of single InP-based
(a) µ-PL spectrum of a single InP-based quantum dot (QD). The inset shows the 2x2 µm2 2D AFM image of low-density QDs. (b) Single photon emission at telecommunication wavelengths from single InP-based QDs. (c) Coherent properties of single InP-based QDs. (d) The measured g-factors for electrons (full squares) and holes (open circles) for QDs emitting at telecommunication wavelengths.

Literature: 

InP-based photonic crystal structures:

(a) μ-PL spectra of the L3 photonic crystal (PK) microresonator at 10 K (red line) and 300 K (black line) with a laser excitation power of 70 μW.(b) μ-PL spectra of the L3 PK microresonator: black line without polarization, red line with horizontal polarization and blue line with vertical polarization.insets: SEM image of the L3 PK microresonator. (c) μ-PL spectra of a single QPkt recorded at three different laser powers, showing excitonic (X) and biexcitonic (XX) emission lines. (d) X- and XX-PL intensities as a function of laser excitation power. The dotted and dashed lines fit to a slope of 0.8 and 1.7. (e) X and XX transitions plotted at 0° (red) and 90° (black) polarization angle, showing vanishing fine structure splitting.

Literature:

Silicon-based quantum dots

Left: InAs QP embedded in a silicon matrix (in cooperation with PDI Berlin). Right: Light emission from single InAs/GaAs core-shell QP grown directly on silicon.
Left: InAs QP embedded in a silicon matrix (in cooperation with PDI Berlin). Right: Light emission from single InAs/GaAs core-shell QP grown directly on silicon.

Literature: 

GaAs-based quantum dots:

(a & b) Single photon emission and X lifetime of single QP grown by droplet epitaxy (in cooperation with HU Berlin).(c)Quality factor enhancement in coupled resonators (in cooperation with Uni. Magdeburg and IFW Dresden).

Literature:

Spatially controlled quantum dots on pre-structured GaAs and silicon substrates:

Left: Spatially controlled QP on GaAs substrates. Right: III-V nanostructures localized in pre-structured silicon nanoholes.

Literature: