Photoluminescence studies of type-II diluted magnetic semiconductor ZnMnTe∕ZnSe quantum dots

Kuo, M. C.; Hsu, Jy-Shan; Shen, Ji Lin; Chiu, Kuan−Cheng; Fan, W. C.; Lin, Yong; Chia, C. H.; Chou, Wu–Ching; Yasar, M.; Mallory, R.; Petrou, A.; Luo, Hongyu

doi:10.1063/1.2424654

Cited by 26 publications

(24 citation statements)

References 20 publications

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“…All samples were grown by MBE on (100) GaAs substrates. The details of sample growth have been given elsewhere 33 . All the QDs have a disk shape with an average 20nm base diameter and a height of 3nm as determined from cross sectional transmission electron microscopy studies.…”

Section: Methodsmentioning

confidence: 99%

“…[1][2][3][4] Compared to their bulk counterparts, [5][6][7][8][9] magnetically doped semiconductor QDs could provide control of the magnetic ordering, [10][11][12][13][14][15][16] with the onset of magnetization at substantially higher temperatures. [17][18][19][20][21] Experiments typically focus on Mn-doped II-VI and III-V QDs, in which it is possible to include both single [22][23][24][25] and several magnetic impurities, [17][18][19][20][21][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] having similarities with nuclear spins. 41,42 In the first case (single magnetic ion), such systems could be considered as potential quantum bits, quantum memories, or probes to detect an unconventional orbital ordering.…”

Section: Introductionmentioning

confidence: 99%

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Time-resolved magnetophotoluminescence studies of magnetic polaron dynamics in type-II quantum dots

et al. 2015

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We used continuous wave photoluminescence (cw-PL) and time resolved photoluminescence (TR-PL) spectroscopy to compare the properties of magnetic polarons (MP) in two related spatially indirect II-VI epitaxially grown quantum dot systems. In the ZnTe/(Zn,Mn)Se system the holes are confined in the non-magnetic ZnTe quantum dots (QDs), and the electrons reside in the magnetic (Zn,Mn)Se matrix. On the other hand, in the (Zn,Mn)Te/ZnSe system, the holes are confined in the magnetic (Zn,Mn)Te QDs, while the electrons remain in the surrounding nonmagnetic ZnSe matrix. The magnetic polaron formation energies MP E in both systems were measured from the temporal red-shift of the band-edge emission. The magnetic polaron exhibits distinct characteristics depending on the location of the Mn ions. In the ZnTe/(Zn,Mn)Se system the magnetic polaron shows conventional behavior with MP E decreasing with increasing temperature T and increasing magnetic field B. In contrast, MP E in the (Zn,Mn)Te/ZnSe system has unconventional dependence on temperature T and magnetic field B; MP E is weakly dependent 2 on T as well as on B. We discuss a possible origin for such a striking difference in the MP properties in two closely related QD systems.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Time-resolved magnetophotoluminescence studies of magnetic polaron dynamics in type-II quantum dots

et al. 2015

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“…This is indeed shown to be the case in Figure 3, where the position of the PL peak does not exhibit any visible oscillations, but rather a slight reduction in the transition energy with magnetic field. The origin of this behavior is related to the Zeeman contribution to the emission, the behavior of which is discussed in Ref [13].Despite the absence of AB oscillations in the PL energy, the strength of the oscillations in the emission intensity increases with magnetic field. This can be seen more clearly in the lower (right) inset…”

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confidence: 98%

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Coherent Aharonov-Bohm oscillations in type-II (Zn,Mn)Te/ZnSe quantum dots

et al. 2008

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The magneto-photoluminescence of type-II (ZnMn)Te quantum dots is presented. As a result of the type-II band alignment Aharonov-Bohm (AB) oscillations in the photoluminescence intensity are evident, confirming previous predictions for the suitability of this geometry to control the optical Aharonov-Bohm effect. Moreover, the system demonstrates an interesting interplay between the AB effect and the spin polarization in diluted magnetic semiconductor quantum dots. The intensity of the AB oscillations increases with both magnetic field and the degree of optical polarization, indicating the suppression of spin fluctuations improves the coherence of the system. * isellers@buffalo.edu 2The Aharonov-Bohm (AB) effect describes a phase shift induced upon a charged particle as it moves in a closed trajectory in the presence of a magnetic field [1]. Despite the fact that the AB effect is a property of charged particles it has been shown that for neutral excitons in semiconductor nano-rings, a non-zero electric dipole moment exists [2,3], which is adequate to create AB oscillations. Such behavior results from the inherent differences in confinement potential and effective mass of the particles comprising the exciton, the electron and hole, and leads to different trajectories for each of the charge carriers, resulting in a measurable AB effect. Type-II quantum dots (QDs) have been predicted to be particularly amenable to exhibiting such AB effects because of the enhanced polarization of the electron and hole due to the spatial separation of the carriers in such systems [3,4].In this work we present experimental evidence of AB oscillations i n the magnetophotoluminescence (MPL) of type-II (ZnMn)Te/ZnSe QDs. In this system the hole is strongly confined within the (ZnMn)Te QD while the electron resides in the ZnSe matrix, confined only through coulomb attraction to the hole. Although the AB effect has been observed optically for charged excitons in In(Ga)As QDs [5] and neutral excitons in both Type-II GaAs/InP [6] and Zn(SeTe ) QDs [7,8], and also in capacitance [10] and magnetization measurements [11] in InAs quantum rings, this is the first time such effects have been observed in a diluted magnetic semiconductor (DMS) system. In DMS systems the application of a magnetic field strongly aligns the Mn spins, thus polarizing the emission through the carrier-Mn exchange [12]. At saturation polarization the carrier spins will also be preferentially aligned, significantly reducing the spin disorder in the system [9,10].The samples studied were grown by MBE on (001) GaAs substrates. The GaAs buffer layer was planarized at 580ºC before the temperature was reduced to 300ºC to deposit a ZnSe buffer. The active layers were grown by migration enhanced epitaxy initiated by the growth of several mono-layers of ZnSe followed by the deposition of the (ZnMn)Te QDs. In the sample described here, five 2.6 ML 3 (ZnMn)Te QD layers were grown, separated by narrow (5 nm) ZnSe spacer layers. The QD density of each layer was estimated from atomic for...

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“…We focus on MPs formed by exchange interaction of a single hole with multiple Mn spins embedded in II-VI self-assembled QDs, as in the experimental studies of Refs. [8,9]. We use the Luttinger-Kohn Hamiltonian to describe quantum states of the hole.…”

Section: Introductionmentioning

confidence: 99%

Multiband Electronic Structure of Magnetic Quantum Dots: Numerical Studies

et al. 2018

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Semiconductor quantum dots (QDs) doped with magnetic impurities have been a focus of continuous research for a couple of decades. A significant effort has been devoted to studies of magnetic polarons (MP) in these nanostructures. These collective states arise through exchange interaction between a carrier confined in a QD and localized spins of the magnetic impurities (typically: Mn). Our theoretical description of various MP properties in self-assembled QDs is discussed. We present a self-consistent, temperature-dependent approach to MPs formed by a valence band hole. The Luttinger-Kohn k ¤ p Hamiltonian is used to account for the important effects of spin-orbit interaction.

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Photoluminescence studies of type-II diluted magnetic semiconductor ZnMnTe∕ZnSe quantum dots

Cited by 26 publications

References 20 publications

Time-resolved magnetophotoluminescence studies of magnetic polaron dynamics in type-II quantum dots

Time-resolved magnetophotoluminescence studies of magnetic polaron dynamics in type-II quantum dots

Coherent Aharonov-Bohm oscillations in type-II (Zn,Mn)Te/ZnSe quantum dots

Multiband Electronic Structure of Magnetic Quantum Dots: Numerical Studies

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