Context of project
Quantum dots (QD) usually refer to semiconductor nanostrucutures where carrier movement is confined to 1-dimension. Application of quantum dots range from temperature insensitive QD-lasers, single photon sources and spin coherent control for quantum computing. Recently, type II QDs have attracted attention for their potential as integer part of a new generation of solar cells. It would be interesting to explore the feasibility of obtaining a type II QD structure with large absorption/emission energy tunability together with adequate conditions for coherent manipulation of spins, which is strongly link to the g-factor.
Type II quantum dots ref:
We characterized individual InAsxP1−x/GaInP quantum dots with variable nominal As molar fraction. Magneto-photoluminescence experiments reveal quantum dot emission in a wide range from 1.3 to 1.8 eV, confirming successful incorporation of As into the quantum dots. Transmission electron microscopy reveals a core-cap structure of InAsP quantum dots with an InAs-rich core capped by an InP-rich layer. Inside the core, an average As molar fraction up to x ≈ 0.15 is observed. The heavy-hole g factors are found to be strongly dependent on As molar fraction, while the electron g factors are close to the InP values. This suggests type-II carrier confinement in the studied InAsP dots with holes (electrons) localized in the core (cap) region. Finally, dynamic nuclear polarization is observed, which allows for further insight into structural properties using nuclear magnetic resonance.
Metalorganic vapor phase epitaxy growth, transmission electron microscopy, and magneto-optical spectroscopy of individual quantum dots
O. Del Pozo-Zamudio, J. Puebla, A. Krysa, R. Toro, A.M. Sanchez, R. Beanland, A.I. Tartakovskii, M.S. Skolnick, E.A. Chekhovich
Physical Review Materials 1 (3), 034605 (2017)
Personal contribution: Project co-leader (corresponding author), analysis of quantum dot density by optical spectroscopy, study of dynamic nuclear polarisation
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