Blueshifts of the emission energy in type-II quantum dot and quantum ring nanostructures

Physics

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https://doi.org/10.1063/1.4818834
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Keywords

LASERS, PHOTOLUMINESCENCE, LOCALIZATION, TEMPERATURE, DEPENDENCE, WELLS

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Blueshifts of the emission energy in type-II quantum dot and quantum ring nanostructures. / Hodgson, P. D.; Young, R. J.; Kamarudin, M. Ahmad et al.
In: Journal of Applied Physics, Vol. 114, No. 7, 073519, 21.08.2013.

Research output: Contribution to Journal/Magazine › Journal article › peer-review

Bibtex

@article{e5e19d37cb3f43848d26a42bb5e31a79,

title = "Blueshifts of the emission energy in type-II quantum dot and quantum ring nanostructures",

abstract = "We have studied the ensemble photoluminescence (PL) of 11 GaSb/GaAs quantum dot/ring (QD/QR) samples over >= 5 orders of magnitude of laser power. All samples exhibit a blueshift of PL energy, Delta E, with increasing excitation power, as expected for type-II structures. It is often assumed that this blueshift is due to band-bending at the type-II interface. However, for a sample where charge-state sub-peaks are observed within the PL emission, it is unequivocally shown that the blueshift due to capacitive charging is an order of magnitude larger than the band bending contribution. Moreover, the size of the blueshift and its linear dependence on occupancy predicted by a simple capacitive model are faithfully replicated in the data. In contrast, when QD/QR emission intensity, I, is used to infer QD/QR occupancy, n, via the bimolecular recombination approximation (I alpha n(2)), exponents, x, in Delta E alpha I-x are consistently lower than expected, and strongly sample dependent. We conclude that the exponent x cannot be used to differentiate between capacitive charging and band bending as the origin of the blueshift in type-II QD/QRs, because the bimolecular recombination is not applicable to type-II QD/QRs. (C) 2013 AIP Publishing LLC.",

keywords = "LASERS, PHOTOLUMINESCENCE, LOCALIZATION, TEMPERATURE, DEPENDENCE, WELLS",

author = "Hodgson, {P. D.} and Young, {R. J.} and Kamarudin, {M. Ahmad} and Carrington, {P. J.} and A. Krier and Zhuang, {Q. D.} and Smakman, {E. P.} and Koenraad, {P. M.} and M. Hayne",

year = "2013",

month = aug,

day = "21",

doi = "10.1063/1.4818834",

language = "English",

volume = "114",

journal = "Journal of Applied Physics",

issn = "0021-8979",

publisher = "AMER INST PHYSICS",

number = "7",

}

RIS

TY - JOUR

T1 - Blueshifts of the emission energy in type-II quantum dot and quantum ring nanostructures

AU - Hodgson, P. D.

AU - Young, R. J.

AU - Kamarudin, M. Ahmad

AU - Carrington, P. J.

AU - Krier, A.

AU - Zhuang, Q. D.

AU - Smakman, E. P.

AU - Koenraad, P. M.

AU - Hayne, M.

PY - 2013/8/21

Y1 - 2013/8/21

N2 - We have studied the ensemble photoluminescence (PL) of 11 GaSb/GaAs quantum dot/ring (QD/QR) samples over >= 5 orders of magnitude of laser power. All samples exhibit a blueshift of PL energy, Delta E, with increasing excitation power, as expected for type-II structures. It is often assumed that this blueshift is due to band-bending at the type-II interface. However, for a sample where charge-state sub-peaks are observed within the PL emission, it is unequivocally shown that the blueshift due to capacitive charging is an order of magnitude larger than the band bending contribution. Moreover, the size of the blueshift and its linear dependence on occupancy predicted by a simple capacitive model are faithfully replicated in the data. In contrast, when QD/QR emission intensity, I, is used to infer QD/QR occupancy, n, via the bimolecular recombination approximation (I alpha n(2)), exponents, x, in Delta E alpha I-x are consistently lower than expected, and strongly sample dependent. We conclude that the exponent x cannot be used to differentiate between capacitive charging and band bending as the origin of the blueshift in type-II QD/QRs, because the bimolecular recombination is not applicable to type-II QD/QRs. (C) 2013 AIP Publishing LLC.

AB - We have studied the ensemble photoluminescence (PL) of 11 GaSb/GaAs quantum dot/ring (QD/QR) samples over >= 5 orders of magnitude of laser power. All samples exhibit a blueshift of PL energy, Delta E, with increasing excitation power, as expected for type-II structures. It is often assumed that this blueshift is due to band-bending at the type-II interface. However, for a sample where charge-state sub-peaks are observed within the PL emission, it is unequivocally shown that the blueshift due to capacitive charging is an order of magnitude larger than the band bending contribution. Moreover, the size of the blueshift and its linear dependence on occupancy predicted by a simple capacitive model are faithfully replicated in the data. In contrast, when QD/QR emission intensity, I, is used to infer QD/QR occupancy, n, via the bimolecular recombination approximation (I alpha n(2)), exponents, x, in Delta E alpha I-x are consistently lower than expected, and strongly sample dependent. We conclude that the exponent x cannot be used to differentiate between capacitive charging and band bending as the origin of the blueshift in type-II QD/QRs, because the bimolecular recombination is not applicable to type-II QD/QRs. (C) 2013 AIP Publishing LLC.

KW - LASERS

KW - PHOTOLUMINESCENCE

KW - LOCALIZATION

KW - TEMPERATURE

KW - DEPENDENCE

KW - WELLS

U2 - 10.1063/1.4818834

DO - 10.1063/1.4818834

M3 - Journal article

VL - 114

JO - Journal of Applied Physics

JF - Journal of Applied Physics

SN - 0021-8979

IS - 7

M1 - 073519

ER -

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