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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 - Extended excitons and compact heliumlike biexcitons in type-II quantum dots.
AU - Bansal, Bhavtosh
AU - Godefroo, Stefanie
AU - Hayne, Manus
AU - Medeiros-Ribeiro, Gilberto
AU - Moshchalkov, Victor
N1 - ©2009 The American Physical Society
PY - 2009/11/18
Y1 - 2009/11/18
N2 - We have used magneto-photoluminescence measurements to establish that InP/GaAs quantum dots have a type-II band (staggered) alignment. The average excitonic Bohr radius and the binding energy are estimated to be 15 nm and 1.5 meV respectively. When compared to bulk InP, the excitonic binding is weaker due to the repulsive (type-II) potential at the hetero-interface. The measurements are extended to over almost six orders of magnitude of laser excitation powers and to magnetic fields of up to 50 tesla. It is shown that the excitation power can be used to tune the average hole occupancy of the quantum dots, and hence the strength of the electron-hole binding. The diamagnetic shift coe±cient is observed to drastically reduce as the quantum dot ensemble makes a gradual transition from a regime where the emission is from (hydrogen-like) two-particle excitonic states to a regime where the emission from (helium-like) four-particle biexcitonic states also become significant.
AB - We have used magneto-photoluminescence measurements to establish that InP/GaAs quantum dots have a type-II band (staggered) alignment. The average excitonic Bohr radius and the binding energy are estimated to be 15 nm and 1.5 meV respectively. When compared to bulk InP, the excitonic binding is weaker due to the repulsive (type-II) potential at the hetero-interface. The measurements are extended to over almost six orders of magnitude of laser excitation powers and to magnetic fields of up to 50 tesla. It is shown that the excitation power can be used to tune the average hole occupancy of the quantum dots, and hence the strength of the electron-hole binding. The diamagnetic shift coe±cient is observed to drastically reduce as the quantum dot ensemble makes a gradual transition from a regime where the emission is from (hydrogen-like) two-particle excitonic states to a regime where the emission from (helium-like) four-particle biexcitonic states also become significant.
KW - type-II
KW - quantum dots
KW - exciton
KW - hydrogen
KW - heliium
UR - http://www.scopus.com/inward/record.url?scp=77954719356&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.80.205317
DO - 10.1103/PhysRevB.80.205317
M3 - Journal article
VL - 80
JO - Physical review B
JF - Physical review B
SN - 1098-0121
IS - 20
M1 - 205137
ER -