References of "Applied Physics Letters"
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See detailSupraferromagnetic correlations in clusters of magnetic nanoflowers
Bender, Philipp Florian UL; Honecker, Dirk UL; Fernández Barquín, Luis

in Applied Physics Letters (2019), 115

Magnetic nanoflowers are densely packed aggregates of superferromagnetically coupled iron oxide nanocrystallites, which excel during magnetic hyperthermia experiments. Here, we investigate the nature of ... [more ▼]

Magnetic nanoflowers are densely packed aggregates of superferromagnetically coupled iron oxide nanocrystallites, which excel during magnetic hyperthermia experiments. Here, we investigate the nature of the moment coupling within a powder of such nanoflowers using spin-resolved small-angle neutron scattering. Within the powder, the nanoparticles are agglomerated to clusters, and we can show that the moments of neighboring nanoflowers tend to align parallel to each other. Thus, the whole system resembles a hierarchical magnetic nanostructure consisting of three distinct levels, i.e., (i) the ferrimagnetic nanocrystallites as building blocks, (ii) the superferromagnetic nanoflowers, and (iii) the supraferromagnetic clusters of nanoflowers. We surmise that such a supraferromagnetic coupling explains the enhanced magnetic hyperthermia performance in the case of interacting nanoflowers. [less ▲]

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See detail3D tomography of cells in micro-channels
Wagner, Christian UL; Quint, Serket; Guckenberger, A. et al

in Applied Physics Letters (2017)

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See detailMagnetoplasmonic control of plasmonic vortices
Maccaferri, Nicolò UL; Gorodetski, Yuri; Toma, Andrea et al

in Applied Physics Letters (2017), 111(20), 201104

We theoretically investigate the generation of far-field propagating optical beams with a desired orbital angular momentum by using an archetypical magnetoplasmonic tip surrounded by a gold spiral slit ... [more ▼]

We theoretically investigate the generation of far-field propagating optical beams with a desired orbital angular momentum by using an archetypical magnetoplasmonic tip surrounded by a gold spiral slit. The use of a magnetic material can lead to important implications once magneto-optical activity is activated through the application of an external magnetic field. The physical model and the numerical study presented here introduce the concept of magnetically tunable plasmonic vortex lens, namely a magnetoplasmonic vortex lens, which ensures a tunable selectivity in the polarization state of the generated nanostructured beam. The presented system provides a promising platform for a localized excitation of plasmonic vortices followed by their beaming in the far-field with an active modulation of both light's transmission and helicity. Published by AIP Publishing. [less ▲]

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See detailTime resolved photoluminescence on Cu(In, Ga)Se-2 absorbers: Distinguishing degradation and trap states
Redinger, Alex UL; Levcenko, Sergiu; Hages, Charles J. et al

in APPLIED PHYSICS LETTERS (2017), 110(12),

Recent reports have suggested that the long decay times in time resolved photoluminescence (TRPL), often measured in Cu(In, Ga)Se-2 absorbers may be a result of detrapping from sub-bandgap defects. In ... [more ▼]

Recent reports have suggested that the long decay times in time resolved photoluminescence (TRPL), often measured in Cu(In, Ga)Se-2 absorbers may be a result of detrapping from sub-bandgap defects. In this work, we show via temperature dependent measurements, that long lifetimes >50 ns can be observed that reflect the true minority carrier lifetime not related to deep trapping. Temperature dependent time resolved photoluminescence and steady state photoluminescence imaging measurements are used to analyze the effect of annealing in air and in a nitrogen atmosphere between 300K and 350K. We show that heating the Cu(In, Ga)Se-2 absorber in air can irreversibly decrease the TRPL decay time, likely due to a deterioration of the absorber surface. Annealing in an oxygen-free environment yields a temperature dependence of the TRPL decay times in accordance with Schockley Read Hall recombination kinetics and weakly varying capture cross sections according to T-0.6. Published by AIP Publishing. [less ▲]

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See detailSpace-charge-limited currents in CIS-based solar cells
Zelenina, Anastasiya UL; Werner, Florian UL; Elanzeery, Hossam UL et al

in Applied Physics Letters (2017), 111

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See detailNano-light-emitting-diodes based on InGaN mesoscopic structures for energy saving optoelectronics
Mikulics, Martin; Winden, Andreas; Marso, Michel UL et al

in Applied Physics Letters (2016), 109

Vertically integrated III-nitride based nano-LEDs (light emitting diodes) were designed and fabricated for operation in the telecommunication wavelength range in the (p-GaN/InGaN/n-GaN/sapphire) material ... [more ▼]

Vertically integrated III-nitride based nano-LEDs (light emitting diodes) were designed and fabricated for operation in the telecommunication wavelength range in the (p-GaN/InGaN/n-GaN/sapphire) material system. The band edge luminescence energy of the nano-LEDs could be engineered by tuning the composition and size of the InGaN mesoscopic structures. Narrow band edge photoluminescence and electroluminescence were observed. Our mesoscopic InGaN structures (depending on diameter) feature a very low power consumption in the range between 2 nWand 30 nW. The suitability of the technological process for the long-term operation of LEDs is demonstrated by reliability measurements. The optical and electrical characterization presented show strong potential for future low energy consumption optoelectronics. [less ▲]

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See detailDirect electro-optical pumping for hybrid CdSe nanocrystal/III-nitride based nano-light-emitting diodes
Mikulics, Martin; Arango, Y.C.; Winden, Andreas et al

in Applied Physics Letters (2016), 108

We propose a device concept for a hybrid nanocrystal/III-nitride based nano-LED. Our approach is based on the direct electro-optical pumping of nanocrystals (secondary excitation) by electrically driven ... [more ▼]

We propose a device concept for a hybrid nanocrystal/III-nitride based nano-LED. Our approach is based on the direct electro-optical pumping of nanocrystals (secondary excitation) by electrically driven InGaN/GaN nano-LEDs as the primary excitation source. To this end, a universal hybrid optoelectronic platform was developed for a large range of optically active nano- and mesoscopic structures. The advantage of the approach is that the emission of the nanocrystals can be electrically induced without the need of contacting them. The proof of principal was demonstrated for the electro-optical pumping of CdSe nanocrystals. The nano-LEDs with a diameter of 100 nm exhibit a very low current of 8 nA at 5V bias which is several orders of magnitude smaller than for those conventionally used. The leakage currents in the device layout were typically in the range of 8 pA to 20 pA/cm2 at 5V bias. The photon-photon down conversion efficiency was determined to be 27%. Microphotoluminescence and microelectroluminescence characterization demonstrate the potential for future optoelectronics and highly secure “green” information technology applications. [less ▲]

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See detailQuasi Fermi level splitting of Cu-rich and Cu-poor Cu(In,Ga)Se2 absorber layers
Babbe, Finn UL; Choubrac, Léo UL; Siebentritt, Susanne UL

in Applied Physics Letters (2016), 109

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See detailOptical spectroscopy study on the photo-response in multiferroic BiFeO3
Burkert, F.; Kreisel, Jens UL; Kuntscher, C. A.

in APPLIED PHYSICS LETTERS (2016), 109(18),

We investigate the underlying mechanism of the photostriction effect in single-crystalline BiFeO3 by transmission measurements in the infrared and visible frequency range under continuous illumination ... [more ▼]

We investigate the underlying mechanism of the photostriction effect in single-crystalline BiFeO3 by transmission measurements in the infrared and visible frequency range under continuous illumination with a green 532 nm). The small photo-induced changes in the transmission spectrum reveal three well-defined absorption features at 1.22 eV, 1.66 eV, and 2.14 eV, which we assign to charge-transfer excitons and in-gap defect states probably related to oxygen vacancies. The intensity of the three absorption features follows a linear dependence on the illumination intensity for an irradiance above 90 W/m(2). Published by AIP Publishing. [less ▲]

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See detailProbing electronic lifetimes and phonon anharmonicities in high-quality chemical vapor deposited graphene by magneto-Raman spectroscopy
Neumann, Christoph; Halpaap, Donatus; Reichardt, Sven UL et al

in Applied Physics Letters (2015), 107(23), 233105

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See detailDetection of Cu2Zn5SnSe8 and Cu2Zn6SnSe9 phases in co-evaporated Cu2ZnSnSe4 thin-films
Schwarz, Torsten; Marques, Miguel A.L.; Botti, Silvana et al

in Applied Physics Letters (2015), 107

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See detailDiffuse Electroreflectance of thin-film solar cells: Suppression of interference-related lineshape distortions
Krämmer, Christoph; Huber, Christian; Redinger, Alex UL et al

in Applied Physics Letters (2015), 107

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See detailReduction of skin effect losses in double-level-T-gate structure
Mikulics, Martin; Hardtdegen, Hilde; Arango, Y. C. et al

in Applied Physics Letters (2014), 105

We developed a T-gate technology based on selective wet etching yielding 200 nm wide T-gate structures used for fabrication of High Electron Mobility Transistors (HEMT). Major advantages of our process ... [more ▼]

We developed a T-gate technology based on selective wet etching yielding 200 nm wide T-gate structures used for fabrication of High Electron Mobility Transistors (HEMT). Major advantages of our process are the use of only standard photolithographic process and the ability to generate T-gate stacks. A HEMT fabricated on AlGaN/GaN/sapphire with gate length Lg=200 nm and double-stacked T-gates exhibits 60 GHz cutoff frequency showing ten-fold improvement compared to 6 GHz for the same device with 2 um gate length. HEMTs with a double-level-T-gate (DLTG) structure exhibit up to 35% improvement of fmax value compared to a single T-gate device. This indicates a significant reduction of skin effect losses in DLTG structure compared to its standard T-gate counterpart. These results agree with the theoretical predictions. [less ▲]

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See detailThe band gap of Cu2ZnSnSe4: Effect of order-disorder
Rey, Germain UL; Redinger, Alex UL; Sendler, Jan UL et al

in Applied Physics Letters (2014), 105

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See detailExcitons in a mirror: Formation of “optical bilayers” using MoS2 monolayers on gold substrates
Mertens, Jan; Shi, Yumeng; Molina-Sanchez, Alejandro UL et al

in Applied Physics Letters (2014), 104

We report coupling of excitons in monolayers of molybdenum disulphide to their mirror image in an underlying gold substrate. Excitons at the direct band gap are little affected by the substrate whereas ... [more ▼]

We report coupling of excitons in monolayers of molybdenum disulphide to their mirror image in an underlying gold substrate. Excitons at the direct band gap are little affected by the substrate whereas strongly bound C-excitons associated with a van-Hove singularity change drastically. On quartz substrates only one C-exciton is visible (in the blue) but on gold substrates a strong red-shifted extra resonance in the green is seen. Exciton coupling to its image leads to formation of a “mirror biexciton” with enhanced binding energy. Estimates of this energy shift in an emitter-gold system match experiments well. The absorption spectrum of MoS2 on gold thus resembles a bilayer of MoS2 which has been created by optical coupling. Additional top-mirrors produce an “optical bulk.” [less ▲]

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See detailMetastable defect in CuInSe2 probed by modulated photo current experiments above 390K
Luckas, Jennifer Maria UL; Longeaud, Christophe; Bertram, Tobias UL et al

in APPLIED PHYSICS LETTERS (2014), 104

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See detailAtom probe study of Cu2ZnSnSe4 thin-films prepared by co-evaporation and post-deposition annealing
Schwarz; Cojocaru-Mirédin, O.; Choi, P. et al

in Applied Physics Letters (2013), 102

Detailed reference viewed: 132 (9 UL)