arXiv subjects

Emanuele Pelucchi

Publications and source records attributed to Emanuele Pelucchi.

23 records · Page 2Linked to original sources

arXiv2014

Spectral signatures of high-symmetry quantum dots and effects of symmetry breaking

A sequence of photoluminescence spectroscopy based methods are used to rigorously identify and study all the main spectral features (more than thirty emission lines) of site controlled InGaAs/AlGaAs quantum dots (QDs) grown along [111]B in inverted tetrahedral pyramids. The studied QDs reveal signatures of one confined electron level, one heavy-hole-like level and one light-hole-like level. The various heavy-light-hole hybrid exciton complexes formed in these QDs are studied by polarization resolved spectroscopy, excitation power dependence, crystal temperature dependence and temporal single photon correlation measurements. The presented approach, which only requires a minimal theoretical input, enables strict spectral identification of the fine structure patterns including weak and spectrally overlapping emission lines. Furthermore, it allows the involved electron-hole and hole-hole exchange interaction energies to be deduced from measurements. Intricate fine structure patterns are qualitatively understood by group theory and shown to be very sensitive to the exact symmetry of the QD. Emission patterns influenced by hole-hole exchange interactions are found to be particularly useful for identifying QDs with high $C_{3v}$ symmetry and for probing symmetry breaking.

cond-mat.mes-hall↗

arXiv2014

Towards quantum dot arrays of entangled photon emitters

We show that with a new family of pyramidal site-controlled InGaAsN quantum dots it is possible to obtain areas containing as much as 15% of polarization-entangled photon emitters - a major improvement if compared to the small fraction achievable by other quantum dot systems. Entanglement is attested by a two-photon polarization state density matrix and the parameters obtained from it. Emitters showing fidelities up to 0.721+-0.043 were found.

cond-mat.mes-hall↗

arXiv2011

Relevance of the purity level in a MetalOrganic Vapour Phase Epitaxy reactor environment for the growth of high quality pyramidal sitecontrolled Quantum Dots

We report in this work on the spectral purity of pyramidal site-controlled InGaAs/AlGaAs Quantum Dots grown by metalorganic vapour phase epitaxy on(111)B oriented GaAs substrates. Extremely sharp emission peaks were found, showing linewidths surprisingly narrow (~27μeV) and comparable to those which can be obtained by Molecular Beam Epitaxy in an ultra-high vacuum environment. A careful reactor handling is regarded as a crucial step toward the fabrication of high optical quality systems.

cond-mat.mtrl-sci↗

arXiv2010

Growth and structural characterization of pyramidal site-controlled quantum dots with high uniformity and spectral purity

This work presents some fundamental features of pyramidal site-controlled InGaAs Quantum Dots (QDs) grown by MetalOrganic Vapour Phase Epitaxy on patterned GaAs (111)B substrate. The dots self-form inside pyramidal recesses patterned on the wafer via pre-growth processing. The major advantage of this growth technique is the control it provides over the dot nucleation posi-tion and the dimensions of the confined structures onto the sub-strate. The fundamental steps of substrate patterning and the QD forma-tion mechanism are described together with a discussion of the structural particulars. The post-growth processes, including sur-face etching and substrate removal, which are required to facili-tate optical characterization, are discussed. With this approach extremely high uniformity and record spectral purity are both achieved.

physics.optics↗

arXiv2010

Low-angle misorientation dependence of the optical properties of InGaAs/InAlAs quantum wells

We investigate the dependence of the low-temperature photoluminescence linewidths from InP-lattice-matched InGaAs/InAlAs quantum wells on the low-angle misorientation from the (100) surface of the host InP substrate. Quantum wells were grown on InP substrates misorientated by 0, 0.2, 0.4 and 0.6 degrees; 0.4 degrees was found to consistently result in the narrowest peaks, with the optimal spectral purity of ~4.25 meV found from a 15nm quantum well. The width of the emission from the 15nm quantum well was used to optimize the growth parameters. Thick layers of Si-doped InGaAs were then grown and found to have bulk, low temperature (77 K), electron mobilities up to μ~ 3.5 x 10^4 cm2/Vs with an electron concentration of ~1 x 10^16.

cond-mat.mtrl-sci↗