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CdSe Quantum Dots Embedded in a ZnCdSe Quantum Well: Towards Efficient Yellow Photoluminescence
I. V. Sedova,O. G. Lyublinskaya,S. V. Sorokin,S. V. Gronin,A. A. Sitnikova,S. V. Ivanov 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5
This paper reports on studies of self-assembled CdSe quantum dot (QD) nanostructures grown by using molecular beam epitaxy in a ZnCdSe quantum well (QW) embedded in ZnSe barriers, which emit in the yellow spectral range (λ = 560 - 570 nm). An up to 180-meV long-wavelength shift of the photoluminescence peak energy, as compared to QDs of the same nominal thickness grown in a ZnSe matrix, was demonstrated. The reasons for that are a decrease in the barrier band gap and an increase in the exciton localization energy in CdSe QDs grown in a ZnCdSe QW. Transmission electron microscopy studies demonstrate an increase in the QD density along with the decreasing their lateral size and a narrowing of the size distribution.
Argunova, T S,Jung, J W,Je, J H,Abrosimov, N V,Grekhov, I V,Kostina, L S,Rozhkov, A V,Sorokin, L M,Zabrodskii, A G Institute of Physics [etc.] 2009 Journal of Physics. D, Applied Physics Vol.42 No.8
<P>Dislocations in p-type Si<SUB>1−<I>x</I></SUB>Ge<SUB><I>x</I></SUB> single crystals (2–8 at% Ge) grown with the Czochralski technique are investigated by synchrotron white beam topography in transmission geometry. As the Ge concentration increases, the dislocation structure evolves from individual dislocations to slip bands and sub-grain boundaries, and the dislocation density increases from <10<SUP>2</SUP> cm<SUP>−2</SUP> to 10<SUP>5</SUP>–10<SUP>6</SUP> cm<SUP>−2</SUP> at 8 at%. We discuss the effect of dislocations on the electrical characteristics such as resistivity ρ<SUB><I>v</I></SUB>, Hall hole mobility μ<SUB>p</SUB>, carrier lifetime τ<SUB>e</SUB> and <I>I</I>–<I>V</I> characteristics. Here τ<SUB>e</SUB> and <I>I</I>–<I>V</I> characteristics are measured from the diodes fabricated by bonding the p-Si<SUB>1−<I>x</I></SUB>Ge<SUB><I>x</I></SUB> to n-Si wafers. <I>I</I>–<I>V</I> characteristics are not deteriorated in spite of a five times decrease in τ<SUB>e</SUB> with the Ge concentration.</P>
Argunova, T. S.,Yi, J. M.,Jung, J. W.,Je, J. H.,Sorokin, L. M.,Gutkin, M. Yu.,Belyakova, E. I.,Kostina, L. S.,Zabrodskii, A. G.,Abrosimov, N. V. WILEY-VCH Verlag 2007 Physica status solidi. PSS. A, Applications and ma Vol.204 No.8
<P>The defect structure of Si<SUB>1–x </SUB>Ge<SUB>x </SUB> wafers with 4% of germanium and their interfaces with Si wafers were studied using white radiation topography and phase-sensitive radiography. The heterostructures were manufactured by direct bonding of Si<SUB>1–x </SUB>Ge<SUB>x </SUB> and Si crystalline wafers made of bulk crystals that were grown by the Czochralski technique. In Si<SUB>1–x </SUB>Ge<SUB>x </SUB> crystals, the segregations of Ge act as dislocation nucleation sites. In Si<SUB>1–x </SUB>Ge<SUB>x </SUB>/Si bonded structures, the segregation of Ge as well as the accumulation of dislocations induce elastic strain and plastic deformation during high-temperature bonding annealing. With the topography–radiography combination, we are able not only to detect microcracks, indicating nonbonded areas, by radiography, but also to reveal dislocations and long-range strain fields by topography at the same time. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)</P>
Magneto-Optical Study of CdSe/CdMgSe/CdMnSe and CdSe/CdMnSe/CdSe Semimagnetic Double Quantum Wells
I. I. Reshina,S. V. Ivanov,I. V. Sedova,I. V. Sorokin 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5
We have studied magneto-photoluminescence and magneto-reflection spectra of two groups of semimagnetic double quantum wells, CdSe/CdMgSe/CdMnSe and CdSe/CdMnSe/CdSe, with either one of the wells or a coupling barrier being semimagnetic. The interaction of the excitons of the coupled wells and their tunneling was controlled by using an applied magnetic field. In the first group of structures, we studied direct and spatially indirect excitons, as well as their polarization and tunneling properties. We also studied the formation of localized magnetic polarons by direct and indirect excitons. In the second group of structures with a semimagnetic coupling barrier, the energy shifts of the excitons under an applied magnetic field significantly exceeded the calculated values obtained without taking into account interface effects. A model that accounted for intrinsic and extrinsic effects at the interfaces of the coupling barrier was successfully used. This model was strongly supported by the experimental evidence in the magneto-reflection spectra. We have studied magneto-photoluminescence and magneto-reflection spectra of two groups of semimagnetic double quantum wells, CdSe/CdMgSe/CdMnSe and CdSe/CdMnSe/CdSe, with either one of the wells or a coupling barrier being semimagnetic. The interaction of the excitons of the coupled wells and their tunneling was controlled by using an applied magnetic field. In the first group of structures, we studied direct and spatially indirect excitons, as well as their polarization and tunneling properties. We also studied the formation of localized magnetic polarons by direct and indirect excitons. In the second group of structures with a semimagnetic coupling barrier, the energy shifts of the excitons under an applied magnetic field significantly exceeded the calculated values obtained without taking into account interface effects. A model that accounted for intrinsic and extrinsic effects at the interfaces of the coupling barrier was successfully used. This model was strongly supported by the experimental evidence in the magneto-reflection spectra.
Kovaleva, Evgenia A.,Kuzubov, Alexander A.,Avramov, Pavel V.,Kholtobina, Anastasia S.,Kuklin, Artem V.,Tomilin, Felix N.,Sorokin, Pavel B. Elsevier 2017 Computational materials science Vol.139 No.-
<P><B>Abstract</B></P> <P>Atomic and electronic structure of LSMO-based composites with carbon nanotubes were studied by means of density functional theory with respect to the termination of LSMO surface. The deformation of the tubes caused by the lattice mismatch with the substrate leads to a major change in their electronic structure. The surface terminated with Mn-O layer provides much stronger interaction with carbon nanotubes than Sr-O terminated one does. The interaction with transition metal atoms is essential for spin polarization of the nanotube while no spin injection was observed for Sr-O-supported tubes.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>