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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Exciton confinement in strain-engineered metamorphic InAs/InxGa1-xAs quantum dots
AU - Khattak, Shaukat Ali
AU - Hayne, Manus
AU - Huang, Junwei
AU - Vanacken, Johan
AU - Moshchalkov, Victor
AU - Seravalli, Luca
AU - Trevisi, Giovanna
AU - Frigeri, Paola
PY - 2017/11/15
Y1 - 2017/11/15
N2 - We report a comprehensive study of exciton confinement in self-assembled InAs quantum dots (QDs) in strain-engineered metamorphic InxGa1-xAs confining layers on GaAs using low temperature magneto-photoluminescence. As the lattice mismatch (strain) between QDs and confining layers (CLs) increases from 4.8% to 5.7% the reduced mass of the exciton increases, but saturates at higher mismatches. At low QD-CL mismatch there is a clear evidence of spillover of the exciton wave-function due to small localisation energies. This is suppressed as the In content, x, in the CLs decreases (mismatch and localisation energy increasing). The combined effects of low effective mass and wave-function spillover at high x result in a diamagnetic shift coefficient that is an order of magnitude larger than for samples where In content in the barrier is low (mismatch is high and localisation energy is large). Finally, an anomalously small measured Bohr radius in samples with the highest x is attributed to a combination of thermalisation due to low localisation energy, and its enhancement with magnetic field, a mechanism which results in small dots in the ensemble dominating the measured Bohr radius.
AB - We report a comprehensive study of exciton confinement in self-assembled InAs quantum dots (QDs) in strain-engineered metamorphic InxGa1-xAs confining layers on GaAs using low temperature magneto-photoluminescence. As the lattice mismatch (strain) between QDs and confining layers (CLs) increases from 4.8% to 5.7% the reduced mass of the exciton increases, but saturates at higher mismatches. At low QD-CL mismatch there is a clear evidence of spillover of the exciton wave-function due to small localisation energies. This is suppressed as the In content, x, in the CLs decreases (mismatch and localisation energy increasing). The combined effects of low effective mass and wave-function spillover at high x result in a diamagnetic shift coefficient that is an order of magnitude larger than for samples where In content in the barrier is low (mismatch is high and localisation energy is large). Finally, an anomalously small measured Bohr radius in samples with the highest x is attributed to a combination of thermalisation due to low localisation energy, and its enhancement with magnetic field, a mechanism which results in small dots in the ensemble dominating the measured Bohr radius.
U2 - 10.1103/PhysRevB.96.195301
DO - 10.1103/PhysRevB.96.195301
M3 - Journal article
VL - 96
JO - Physical review B
JF - Physical review B
SN - 2469-9950
IS - 19
M1 - 195301
ER -