Dresden 2017 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 9: Quantum Dots: Preparation and Characterization

HL 9.6: Talk

Monday, March 20, 2017, 10:45–11:00, POT 112

MOVPE grown InAs quantum dots on InGaAs/GaAs metamorphic buffers — •Susanne Schreier, Matthias Paul, Fabian Olbrich, Jonatan Höschele, Michael Jetter, and Peter Michler — Institut für Halbleiteroptik und funktionelle Grenzflächen, Universität Stuttgart and Research Centers SCoPE and IQ^ST, Allmandring 3, 70569 Stuttgart

In the last years the interest in quantum computing and cryptography and therefore the need for single-photon sources increased strongly. InAs semiconductor quantum dots (QDs) are promising candidates for sources of entangled or indistinguishable photons due to their good optical properties. The implementation in glass fiber networks requires emission wavelengths of 1310 nm (O-band) and 1550 nm (C-band), corresponding to the dispersion and absorption minima. To reach these wavelengths the typical emission energies of InAs QDs need to be red shifted. This can be realized by reducing the lattice mismatch between GaAs and InAs by the use of an InGaAs metamorphic buffer layer below the QDs. The buffer layer functions, similar to InP substrates, to reduce the strain in the QDs. This leads to a reduction of the effective band gap and to an increase in size of the QDs, which results in a lower emission energy. In contrast to InP substrates, the extraction efficiency for photoluminescence (PL) measurements can be enhanced by AlAs/GaAs distributed Bragg reflectors below both the metamorphic buffer and the QDs. The characterization involves XRD and AFM to investigate the structural properties and PL to investigate the optical properties of the InAs QDs.