Optical spectroscopy of CdTe/ZnTe quantum-dot superlattices

Onishchenko, E. E.; Багаев, В. С.; Зайцев, В. В.; Makhov, E.I.

doi:10.1016/j.physe.2004.08.043

Cited by 7 publications

(6 citation statements)

References 8 publications

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“…It can be attributed to excitons localized at correlated CdTe islands (QDs) in the adjacent QD planes (QDs are electronically coupled in such a case). It has been also established that the ZnTe spacer thickness decrease affects substantially the PL temperature dependence of QD structures [2]. PL spectra of the structures are presented in Fig.…”

Section: Methodsmentioning

confidence: 86%

“…3) increase. This difference may be explained as follows: as it has been shown in [2], the electronically coupled QD emission band is caused by spatially indirect excitons in the B12 structure, in this case, a potential well for a light hole caused by elastic strain and Coulomb interaction with an electron is rather shallow and a radiative recombination time of an indirect exciton exceeds substantially that of a direct exciton. These factors should lead to a rapid quenching of electronically coupled QD PL with the temperature increase (activation energy of PL quenching in CdTe/ZnTe structures is defined by a potential well depth for a hole [5]) and redistribution of relative PL intensities of the isolated and coupled QD emission bands with the pumping power increase.…”

Section: Methodsmentioning

confidence: 94%

“…Strain distribution patterns are different for these samples (QD superlattices). For the B12 sample ZnTe spacer layers are strongly strained and, as a consequence, the long-wavelength emission band is caused by spatially indirect excitons (electrons are localized in QDs and light holes are localized in strain-driven potential wells in regions between QDs in adjacent QD layers) [2]. On the contrary, ZnTe spacer layers are less strained in the B10-200 sample because of strain relaxation occurred in the sample that, in principle, can result in change of band diagram type.…”

Section: Methodsmentioning

confidence: 99%

“…Due to CdTe/ZnTe system feature (valence-band offset is controlled mainly by elastic strain caused by the large lattice mismatch between CdTe and ZnTe [1]), the elastic strain affects electronic and optical spectra of CdTe/ZnTe QD multilayers particularly strongly. It has been shown earlier for CdTe/ZnTe QD multilayers grown on a thick CdTe buffer layer that an unusual situation can occur in the samples with a small ZnTe spacer layer thickness, when the photoluminescence (PL) spectrum of QD structure is caused by two kinds of excitonic states -spatially direct and spatially indirect [2]. The CdTe/ZnTe QD multilayers grown on a thick ZnTe buffer layer have been studied in this work by optical spectroscopy methods.…”

Section: Introductionmentioning

confidence: 99%

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Optical spectroscopy of CdTe/ZnTe quantum dot multilayers

Onishchenko

Багаев

Karczewski

et al. 2006

Phys. Status Solidi (c)

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Electronic and vibrational states in CdTe/ZnTe quantum dot multilayers grown on a thick ZnTe buffer layer are studied using optical spectroscopy methods (photoluminescence in a wide temperature range, Raman scattering, and IR reflection). It has been established that a new band appears in the Raman spectra of sample with a small ZnTe spacer layer thickness, which can be ascribed to a vibrational mode of two closely-spaced quantum dots. A comparison of results obtained under studies of structures grown on ZnTe and CdTe buffer layers shows that change of strain distribution pattern substantially modifies electron and optical spectra of QD structures. In particular, it can result in change of the band diagram type. A reason of anomalous peak position shift of quantum dot emission band is discussed.

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Section: Methodsmentioning

confidence: 86%

Section: Methodsmentioning

confidence: 94%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Optical spectroscopy of CdTe/ZnTe quantum dot multilayers

Onishchenko

Багаев

Karczewski

et al. 2006

Phys. Status Solidi (c)

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“…But, likely, it is not the case: the spectral position of emission band for the structure has a blue-shift more than 150 meV with respect to QD multilayer with analogous CdSe layer thickness grown on GaAs substrate. It has been shown that the activation energy for II-VI QD multilayers can differ from that for single-layer QDs even for nominally equal thickness of QD layer material [6,9,10]. Usually, the activation energy for multilayers is higher [6,9].…”

Section: Pl Integrated Intensitymentioning

confidence: 99%

Temperature dependence of photoluminescence of CdSe/ZnSe quantum dots grown on GaAs and Si/Ge virtual substrates

Onishchenko

Багаев

Казаков

et al. 2006

Phys. Status Solidi (c)

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We have carried out temperature-dependent studies of the photoluminescence properties of a set of CdSe/ZnSe quantum dot structures grown on conventionally used GaAs(100) substrates and Si(100)/Ge virtual substrates. Both single-layer and multilayer QD structures have been studied. It was shown that the conventional MBE technique allows to grow CdSe/ZnSe QDs having the activation energy of luminescence quenching as large as 200 meV. Such issues as possible reasons of such a large activation energy and exciton migration in QD planes are discussed.1 Introduction Growth of self-assembled II-VI and III-V quantum dots (QDs) on Si substrates is of a crucial importance for the integration of optoelectronic devices with the mainstream silicon-based technology. It is difficult to obtain high-quality ZnSe epilayers directly on the Si substrate due to large lattice mismatch between these semiconductors. ZnSe and Ge have close lattice constants and, consequently, Ge is more convenient material for growing ZnSe-based heterostructures than Si. In principle, a sequence of epitaxial layers can be grown on Si substrates which has Ge-layer with relatively high structural quality as a cap layer. Such epitaxial structure can be used as a substrate (so-called "virtual" substrate) for growth of ZnSe.A new technique of growth of high-quality CdSe/ZnSe QD structures on virtual Si(100)/Ge substrates has recently been developed by our group. TEM and X-ray studies have showed that high-quality selfassembled CdSe/ZnSe QD structures could be grown on Si/Ge virtual substrates [1]. It was established also that the photoluminescence (PL) efficiency of such structures is comparable with those of analogous QD structures grown on GaAs substrates [2].It is important for design of II-VI QD blue-green laser structures and light-emitting devices integrated with the silicon-based technology and operated at room temperature to study the influence of structure parameters on the temperature dependence of their luminescent properties. Studies of the PL temperature dependence of CdSe/ZnSe QDs grown on conventionally used GaAs (100) substrates and Si(100)/Ge virtual substrates are reported.

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Thermopiezoelectric effects on optoelectronic properties of CdTe/ZnTe quantum wires

Patil

Melnik

2009

Physica Status Solidi (a)

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We investigate thermopiezoelectric field distributions and their effects on electronic properties of the highly strained CdTe/ZnTe quantum wires. The full 3D coupled thermoelectromechanical formulation, consisting of balance equations for heat transfer, electrostatics and the mechanical field, is developed. Effects of thermal loadings on piezoelectric fields are determined for rectangular CdTe/ZnTe quantum wire systems. The conduction band edge shifts due to thermoelectromechancial loadings are calculated. A single band Schrödinger equation is used to determine eigenstates for electrons and the analysis of classical effects are presented. Piezoelectric quantities are observed to be relatively less sensitive to thermal loadings. However, these effects are observed to be important in the determination of electronic/optoelectronic properties of quantum wire systems. The results presented here help improve our understanding of the classical effects on electronic structures and optoelectronic properties of CdTe/ZnTe quantum wires. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Optical spectroscopy of CdTe/ZnTe quantum-dot superlattices

Cited by 7 publications

References 8 publications

Optical spectroscopy of CdTe/ZnTe quantum dot multilayers

Optical spectroscopy of CdTe/ZnTe quantum dot multilayers

Temperature dependence of photoluminescence of CdSe/ZnSe quantum dots grown on GaAs and Si/Ge virtual substrates

Thermopiezoelectric effects on optoelectronic properties of CdTe/ZnTe quantum wires

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