A5083919225- Semiconductor Quantum Structures and Devices
- Rare-earth and actinide compounds
- Graphene research and applications
- Iron-based superconductors research
- Electronic and Structural Properties of Oxides
- Quantum Dots Synthesis And Properties
- Chemical and Physical Properties of Materials
- Carbon Nanotubes in Composites
- Magnetic and transport properties of perovskites and related materials
- Hydrogen Storage and Materials
- Magnetic properties of thin films
- Electron and X-Ray Spectroscopy Techniques
- Organic Electronics and Photovoltaics
- Metal and Thin Film Mechanics
- Physics of Superconductivity and Magnetism
- Solid-state spectroscopy and crystallography
- Magnetic Properties and Synthesis of Ferrites
- Copper-based nanomaterials and applications
- Silicon Nanostructures and Photoluminescence
- Ion-surface interactions and analysis
- Nanowire Synthesis and Applications
- Fluid Dynamics and Thin Films
- Optical properties and cooling technologies in crystalline materials
- Block Copolymer Self-Assembly
- Perovskite Materials and Applications
Deutsches Elektronen-Synchrotron DESY
2020-2024
Saha Institute of Nuclear Physics
2015-2022
Lead-free halide perovskites have attracted interest in the photovoltaic industry out of concern for toxic nature lead. Antimony-based perovskite, cesium antimony iodide (Cs3Sb2I9), is one such material proposed to substitute lead-based perovskites, as it has a high absorption coefficient, nearly direct bandgap, and low effective mass. A clear understanding stability this will bring its efficient use photovoltaics. Here we studied degradation both polymorphs Cs3Sb2I9 (dimer layer forms)...
Superior supramolecular packing and thereby efficient electron transport in economically viable n-type organic semiconductor materials suitable for solution-processed OFET devices yield high mobility ambient stability.
The influence of adding nanoparticles on the ascast morphology spin coated immiscible polystyrene/poly(methyl methacrylate) (PS/PMMA) thin films different thickness (hE) and composition (RB, volume ratio PS to PMMA) has been explored in this article. To understand precise effect nanoparticle addition, PS/PMMA blend cast from toluene a native oxide covered silicon wafer substrate was first investigated. It is seen that particle free films, generic remains nearly unaltered with increase hE,...
Traditionally, the Coulomb repulsion or Peierls instability causes metal-insulator phase transitions in strongly correlated quantum materials. In comparison, magnetic stress is predicted to drive transition materials exhibiting strong spin-lattice coupling. However, this mechanism lacks experimental validation and an in-depth understanding. Here we demonstrate existence of stress-driven archetypal material, chromium nitride. Structural, magnetic, electronic transport characterization,...
Anion exchange of CsPbX3 nanocrystals (NCs) is an easy pathway to tune the bandgap over entire visible region. Even mixing pre-synthesized CsPbBr3 and CsPbI3 NCs at room temperature leads formation mixed halide CsPbBr3-xIx NCs. Understanding reaction mechanism kinetics interparticle essential for fundamental aspects device applications. Here, we probed ion migration through time-dependent steady-state photoluminescence (PL) spectroscopy. We found three primary PL peaks after NCs-bromide side...
Charge carrier transport in bulk organic semiconductors, especially solution-grown films, is invariably dictated by the semiconductor layer morphology and molecular level organization of charge hopping centers. Therefore, even tiny positional displacements molecules will lead to significant changes transport. Various pre- postfilm deposition techniques have been developed achieve ideal arrangement on desired substrates. Herein, demonstrate findings temperature-assisted morphological...
The understanding of the correlation between structural and photoluminescence (PL) properties self-assembled semiconductor quantum dots (QDs), particularly InGaAs QDs grown on (001) GaAs substrates, is crucial for both fundamental research optoelectronic device applications. So far PL have been probed from two different epitaxial layers, namely top-capped buried layers respectively. Here, we report first time measurements an uncapped layer to correlate directly composition, strain shape with...
We show that an unstable thin polymer bilayer comprising a polystyrene (PS) top and polymethyl methacrylate (PMMA) bottom layer remains completely stable on non-wettable, hydrophobized silicon wafer substrate, even after 600 h of thermal annealing at temperature is higher than the glass transition (TG) both polymers, when thiol-capped gold nanoparticles (AuNPs) are added only to PS concentration (CNP) ≈ 10.0% (wt. NP/wt. polymer). also in films with CNP as low 2.5%, PMMA becomes stabilized...
We present time-resolved high energy x-ray diffraction (tr-HEXRD), hard photoelectron spectroscopy (tr-HAXPES) and grazing incidence small angle scattering (tr-GISAXS) data of the reactive molecular beam epitaxy (RMBE) $\mathrm{Fe_3O_4}$ ultrathin films on various substrates. Reciprocal space maps are recorded during deposition $\mathrm{SrTiO_3(001)}$, MgO(001) NiO/MgO(001) in order to observe temporal evolution Bragg reflections sensitive octahedral tetrahedral sublattices inverse spinel...
We investigate the electronic structure of a Kondo lattice system, ${\mathrm{CeCuSb}}_{2}$ exhibiting significant mass enhancement and Kondo-type behavior. observe multiple features in hard x-ray photoemission spectra Ce core levels due to strong final-state effects. The depth-resolved data exhibit change relative intensity with surface sensitivity probe. extracted bulk spectral functions are different Kondo-like feature at higher binding energies addition well poorly screened features....
In the present study, an ionic liquid (IL), known as green solvent, 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4) with four carbons in hydrophobic chain (C-4) has been used additive to modify self-assembled aggregates of anionic surfactant sodium dodecyl sulfate (SDS) and then evolution crystalline phases investigated. Small angle synchrotron x-ray diffraction study revealed unprecedented phase sequence where a hexagonal (HI) direct cylindrical micelles is observed evolve another...
Abstract We investigate the electronic structure of an antiferromagnetic Kondo lattice system CeAgAs 2 employing hard x -ray photoemission spectroscopy. , orthorhombic variant HfCuSi structure, exhibits ground state, like resistivity upturn and compensation magnetic moments at low temperatures. The spectra obtained different photon energies suggest termination cleaved surface cis-trans-As layers. depth-resolved data show significant surface-bulk differences in As Ce core level spectra. p...
Epitaxially grown self-assembled semiconductor quantum dots (QDs) with atom-like optical properties have emerged as the best choice for single-photon sources required development of technology and networks. Nondestructive selection a single QD having desired structural, compositional, characteristics is essential to obtain noise-free, fully indistinguishable or entangled photons from emitters. Here, we show that structural orientations local compositional inhomogeneities within surrounding...
Nanoprobe X-ray diffraction (nXRD) using focused synchrotron radiation is a powerful technique to study the structural properties of individual semiconductor nanowires. However, when performing experiment under ambient conditions, required high dose and prolonged exposure times can lead damage. To unveil origin damage, comparison made nXRD experiments carried out on nanowires in their as-grown geometry both conditions He atmosphere at microfocus station P08 beamline third-generation source...
The interface of two dissimilar materials is well known for surprises in condensed matter, and provides avenues rich physics as seeds future technological advancements. We present some exciting magnetization (M) remanence (μ) results, which conclusively arise at the highly functional materials, namely graphitic shells a carbon nanotube (CNT) α-Fe2O3, Dzyaloshinskii-Moriya interaction driven weak ferromagnet (WFM) piezomagnet (PzM). show that encapsulation inside CNT leads to significant...
Epitaxial InAs quantum dots grown on GaAs substrate are being used in several applications ranging from communications to solar cells. The growth mechanism of these also helps us explore fundamental aspects self-organized processes. Here we show that composition and strain profile the can be tuned by controlling in-plane density over with help substrate-temperature profile. compositional extracted grazing incidence x-ray measurements substantial amount inter-diffusion Ga In within QD as a...
We investigate the photoemission from quantum wells (QWs) in ultrathin films (UFs) and well wires (QWWs) of non-linear optical materials on basis a newly formulated electron dispersion law considering anisotropies effective masses, spin-orbit splitting constants presence crystal field within framework k.p formalism. The results confined Ill-V compounds form special cases our generalized analysis. has also been studied for II-VI, n-GaP, n-Ge, PtSb2, stressed Bismuth respective relations. It...