A5012418295- Chalcogenide Semiconductor Thin Films
- Quantum Dots Synthesis And Properties
- Copper-based nanomaterials and applications
- Semiconductor materials and interfaces
- Photorefractive and Nonlinear Optics
- Advanced Thermoelectric Materials and Devices
- Thin-Film Transistor Technologies
- Structural Health Monitoring Techniques
- Structural Load-Bearing Analysis
- Mechanical stress and fatigue analysis
- Fatigue and fracture mechanics
- X-ray Spectroscopy and Fluorescence Analysis
- Solid-state spectroscopy and crystallography
- Solid State Laser Technologies
- Nuclear materials and radiation effects
- Electrohydrodynamics and Fluid Dynamics
- Laser Material Processing Techniques
- Tree Root and Stability Studies
- Advanced Photonic Communication Systems
- Machine Learning in Materials Science
- Photonic and Optical Devices
- Optical Network Technologies
- Ion-surface interactions and analysis
- Soil Mechanics and Vehicle Dynamics
- ZnO doping and properties
Leipzig University
2019-2025
Friedrich Schiller University Jena
2017-2023
Technische Universität Braunschweig
2019
Robert Bosch (Germany)
2003
Stable Sb exhibits a rhombohedral structure, often referred to as distorted primitive cubic, with each atom having three short and longer first neighbor bonds. However, this crystal structure can also be interpreted being layered, putting emphasis on only Therefore, temperature-dependent extended X-ray absorption fine (EXAFS) spectroscopy is carried out at the K-edge in order obtain more detailed information local structural vibrational properties. Evaluation of bond lengths provides Peierls...
The presence of Ge during the synthesis thin film kesterite Cu2ZnSnSe4 (CZTSe) solar cell absorbers boosts their power conversion efficiency, especially due to an improved open circuit voltage. mechanism underlying this beneficial effect is still under debate. We gained deep insights into role by applying advanced synchrotron nanoprobe-based X-ray fluorescence spectroscopy and absorption near-edge structure cross-sectional lamellas taken from high efficiency devices. observe that remains in...
The atomic-scale structure and vibrational properties of semiconductor alloys are determined by the energy required for stretching bending individual bonds. Using temperature-dependent extended x-ray absorption fine-structure spectroscopy, we have element-specific In-As Ga-As effective bond-stretching force constants in (In,Ga)As as a function alloy composition. results reveal striking inversion bond strength where originally stiffer parent materials becomes softer vice versa. Our findings...
Kesterite based materials are being researched and developed as affordable, efficient, mechanically flexible absorber for thin film photovoltaics. Both (Ag,Cu) 2 ZnSnSe 4 Cu Zn(Sn,Ge)Se devices have shown great potential in overcoming some of the remaining challenges further increasing conversion efficiency kesterite solar cells. This study therefore investigates long range crystallographic structure local atomic scale technologically relevant films by means grazing incidence X-ray...
Abstract Kesterite based materials gain more and relevance in the pursuit of affordable, efficient flexible absorber for thin film photovoltaics. Alloying Cu 2 ZnSnSe 4 with Ge could allow controlled band gap engineering as already established Cu(In,Ga)(S,Se) solar cells. This study investigates local atomic arrangements Zn(Sn,Ge)Se alloys by means low temperature Extended x-ray Absorbtion Fine Structure Spectroscopy. The element specific bond lengths are used together diffraction data to...
Abstract The chalcopyrite alloy (Ag,Cu)(In,Ga)Se 2 is a highly efficient thin film solar cell absorber, reaching record efficiencies above 23 %. Recently, peculiar behavior in the bond length dependence of (Ag,Cu)GaSe was experimentally proven. common cation length, namely Ga-Se, decreases with increasing Ag/(Ag+Cu) ratio even though crystal lattice expands. This opposite to observed for Cu(In,Ga)Se , where all lengths increase size. To better understand this behavior, element-specific...
Highly performing kesterite‐based Cu 2 ZnSn(S,Se) 4 (CZTSSe) thin‐film solar cells are typically produced under Cu‐poor and Zn‐rich synthesis conditions. However, these processing routes also facilitate the formation of secondary phases as well deviations from stoichiometry, causing intrinsic point defects. Herein, local composition CZTSSe absorbers prepared with different nominal cation concentrations is investigated by applying energy dispersive X‐ray spectroscopy synchrotron fluorescence...
Contrary to other semiconductor alloys, incorporation of Ag into CuGaSe2 increases the bandgap, even though lattice expands, and Ga–Se bond length is theoretically predicted decrease rather than increase. Herein, we experimentally confirm this peculiar dependence (Ag,Cu)GaSe2 using x-ray absorption spectroscopy. We further model different anion displacements estimate that their combined contribution bandgap bowing close zero. These findings differ from those for Cu(In,Ga)Se2 demonstrate...
A newly designed setup to perform steady-state X-ray excited optical luminescence (XEOL) spectroscopy and simultaneous XEOL absorption characterization at beamline P65 of PETRA III is described. The equipped with a He-flow cryostat state-of-the-art detection system, which covers wide wavelength range 300-1700 nm high spectral resolution 0.4 nm. To demonstrate the functioning, low-temperature studies on polycrystalline CuInSe
Amorphous Cu–Sn–I is a promising p‐type transparent semiconductor. Therefore, herein, composition and structure of sputtered thin films with varying thickness Sn content are investigated by different electron microscopy techniques, energy‐dispersive X‐ray spectroscopy, absorption spectroscopy at the Cu, Sn, I K‐edge. After exposure to air, found contain significant amounts oxygen, leading complete phase separation resulting Cu–Sn–I–O films. Spatially‐resolved compositional analysis...
The deviation from stoichiometry and the understanding of its consequences are key factors for application kesterites as solar cell absorbers. Therefore, this study investigates local atomic structure off-stoichiometric Cu2ZnSnS4 (CZTS), Cu2ZnSnSe4 (CZTSe) Cu2ZnGeSe4 (CZGSe) by means Extended X-ray Absorption Fine Structure Spectroscopy. Temperature dependent measurements yield bond stretching force constants all cation-anion bonds in stoichiometric CZTS CZTSe nearly CZGSe. Low temperature...
Abstract Es wird eine Studie zur stark lokalisierten Mikroschädigung während der Risseinleitung unter zyklischer Beanspruchung am Baustahl vorgestellt. Hierfür werden gekerbte Proben mit einer im High‐Cycle‐Fatigue‐(HCF‐)Bereich belastet. Die Bauteiloberfläche Bereich Kerbe Electronic Speckle Pattern Interferometry (ESPI) inspiziert, einem Verfahren hochauflösenden und flächenhaften Messung von Dehnungen. Dies geschieht in diskreten Abständen wenigen Tausend Lastwechseln. Auswertung...