Sascha Schäfer
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View article: Second Harmonic Characteristics of Large‐Area ALD‐Grown MoS <sub>2</sub> Monolayers and MoS <sub>2</sub> /WS <sub>2</sub> Heterostructures with Sub‐Millimeter Crystalline Orientation
Second Harmonic Characteristics of Large‐Area ALD‐Grown MoS <sub>2</sub> Monolayers and MoS <sub>2</sub> /WS <sub>2</sub> Heterostructures with Sub‐Millimeter Crystalline Orientation Open
The crystal orientation uniformity of MoS 2 monolayers grown by atomic layer deposition (ALD) on sapphire substrates is investigated, and their integration with spin‐coated WS 2 in a MoS 2 /WS 2 heterostructure. Polarization‐resolved secon…
View article: All-optical stochastic switching of magnetisation textures in Fe3Sn2
All-optical stochastic switching of magnetisation textures in Fe3Sn2 Open
The all-optical control of magnetisation at room temperature broadens the scope of applications of spin degrees-of-freedom in data storage, spintronics, and quantum computing. Topological magnetic spin structures, such as skyrmions, are of…
View article: Laser-driven cold field emission source for ultrafast transmission electron microscopy
Laser-driven cold field emission source for ultrafast transmission electron microscopy Open
Ultrafast transmission electron microscopy (UTEM) has emerged as a versatile technique for the time-resolved imaging of nanoscale dynamics on timescales down to few-hundred attoseconds but the temporal and spatial resolutions are still lim…
View article: Acid-base properties of polydimethylsiloxane based adhesives and their influence on adhesion to polymer surfaces
Acid-base properties of polydimethylsiloxane based adhesives and their influence on adhesion to polymer surfaces Open
This work aimed to investigate the adhesive properties of polysiloxanes (silicones) on polymer surfaces in relation to their acid-base properties. To adjust the acid-base properties of polydimethylsiloxane (PDMS) based formulations, (3-ami…
View article: Laser-driven cold-field emission source for ultrafast transmission electron microscopy
Laser-driven cold-field emission source for ultrafast transmission electron microscopy Open
Ultrafast transmission electron microscopy (UTEM) has emerged as a versatile technique for the time-resolved imaging of nanoscale dynamics on timescales down to few-hundred attoseconds but the temporal and spatial resolutions are still lim…
View article: Visualizing Standing Light Waves in Continuous-Beam Transmission Electron Microscopy
Visualizing Standing Light Waves in Continuous-Beam Transmission Electron Microscopy Open
The phase-resolved imaging of confined light fields by homodyne detection is a cornerstone of metrology in nano-optics and photonics, but its application in electron microscopy has been limited so far. Here, we report the mapping of optica…
View article: Spectrally resolved free electron-light coupling strength in a transition metal dichalcogenide
Spectrally resolved free electron-light coupling strength in a transition metal dichalcogenide Open
Recent advancements in electron microscopy have introduced innovative techniques enabling the inelastic interaction of fast electrons with tightly confined and intense light fields. These techniques, commonly summarized under the term phot…
View article: Inelastic electron-light scattering at dielectric thin films
Inelastic electron-light scattering at dielectric thin films Open
In a recently developed methodology termed photon induced near-field electron microscopy (PINEM), the inelastic scattering of electrons off illuminated nanostructures provides direct experimental access to the structure of optical near-fie…
View article: Electron Imaging of Nanoscale Charge Distributions Induced by Femtosecond Light Pulses
Electron Imaging of Nanoscale Charge Distributions Induced by Femtosecond Light Pulses Open
Surface charging is ubiquitously observable during in situ transmission electron microscopy of nonconducting specimens as a result of electron beam/sample interactions or optical stimuli and often limits the achievable image stability and …
View article: Coherent acoustic phonons in a coupled hexagonal boron nitride–graphite heterostructure
Coherent acoustic phonons in a coupled hexagonal boron nitride–graphite heterostructure Open
Femtosecond optically excited coherent acoustic phonon modes (CAPs) are investigated in a free-standing van der Waals heterostructure composed of a 20-nm transparent hexagonal boron nitride (hBN) and a 42-nm opaque graphite layer. Employin…
View article: CCDC 2194078: Experimental Crystal Structure Determination
CCDC 2194078: Experimental Crystal Structure Determination Open
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available …
View article: Coupling Broadband Terahertz Dipoles to Microscale Resonators
Coupling Broadband Terahertz Dipoles to Microscale Resonators Open
Optically driven spintronic emitters are a unique class of terahertz (THz) sources due to their quasi-two-dimensional geometry and thereby their capability to effectively couple to resonator near fields. Global excitation of the emitters o…
View article: Electron Imaging of Nanoscale Charge Distributions Induced by Femtosecond Light Pulses
Electron Imaging of Nanoscale Charge Distributions Induced by Femtosecond Light Pulses Open
Surface charging is a phenomenon ubiquitously observable in in-situ transmission electron microscopy of non-conducting specimens as a result of electron beam/sample interactions or optical stimuli and often limits the achievable image stab…
View article: Improving the temporal resolution of event-based electron detectors using neural network cluster analysis
Improving the temporal resolution of event-based electron detectors using neural network cluster analysis Open
Novel event-based electron detector platforms provide an avenue to extend the temporal resolution of electron microscopy into the ultrafast domain. Here, we characterize the timing accuracy of a detector based on a TimePix3 architecture us…
View article: Coupling Broadband Terahertz Dipoles to Microscale Resonators
Coupling Broadband Terahertz Dipoles to Microscale Resonators Open
Optically driven spintronic emitters are a unique class of terahertz (THz) sources due to their quasi-two-dimensional geometry and thereby their capability to effectively couple to resonator near fields. Global excitation of the emitters o…
View article: Large‐Area Growth of MoS<sub>2</sub>/WS<sub>2</sub> Heterostructures by a Sequential Atomic Layer Deposition and Spin‐Coating Approach
Large‐Area Growth of MoS<sub>2</sub>/WS<sub>2</sub> Heterostructures by a Sequential Atomic Layer Deposition and Spin‐Coating Approach Open
Despite the plethora of intriguing phenomena observed in heterostructure stacks of 2D transition metal dichalcogenide (2D‐TMDC) flakes, their application in functional devices is still hampered due to the lack of reliable growth methodolog…
View article: Tailored nanophononic wavefield in a patterned bilayer system probed by ultrafast convergent beam electron diffraction
Tailored nanophononic wavefield in a patterned bilayer system probed by ultrafast convergent beam electron diffraction Open
Optically excited nanostructures provide a versatile platform for the generation of confined nanophononic fields with potential (non-)linear interactions between different degrees of freedom. Control of resonance frequencies and the select…
View article: Optoelectronic Properties of MoS<sub>2</sub> in Proximity to Carrier Selective Metal Oxides
Optoelectronic Properties of MoS<sub>2</sub> in Proximity to Carrier Selective Metal Oxides Open
Transition metal dichalcogenides are an exciting class of new absorber materials for photovoltaic applications due to their unique optoelectronic properties in the single to few‐layer regime. In recent years, these materials have been inte…
View article: Identifying dominant recombination locations in double‐graded Cu(In<sub>1‐x</sub>Ga<sub>x</sub>)(Se<sub>1‐y</sub>S<sub>y</sub>)<sub>2</sub> solar cells and their impact on the performance at different light intensities
Identifying dominant recombination locations in double‐graded Cu(In<sub>1‐x</sub>Ga<sub>x</sub>)(Se<sub>1‐y</sub>S<sub>y</sub>)<sub>2</sub> solar cells and their impact on the performance at different light intensities Open
In this work, the impact of different Cu(In 1‐x Ga x )(Se 1‐y S y ) 2 solar cell structures on the shift of the dominant recombination region at varying light intensities was investigated. A new parameter was proposed to account for the do…
View article: Impact of the Buffer/Absorber Interface on the Metastability of Fill Factor Temperature Coefficients in CIGSSe Solar Cells
Impact of the Buffer/Absorber Interface on the Metastability of Fill Factor Temperature Coefficients in CIGSSe Solar Cells Open
The metastable behavior of the fill factor temperature coefficient (β FF,rel ) in Cu(In,Ga)(S,Se) 2 solar cells is investigated for absorbers with a different Ga content in the front surface, and for different buffer materials. The buffer/…
View article: Ultrafast electron microscopy for probing magnetic dynamics
Ultrafast electron microscopy for probing magnetic dynamics Open
The spatial features of ultrafast changes in magnetic textures carry detailed information on microscopic couplings and energy transport mechanisms. Electrons excel in imaging such picosecond or shorter processes at nanometer length scales.…
View article: Micro-patterned deposition of MoS2 ultrathin-films by a controlled droplet dragging approach
Micro-patterned deposition of MoS2 ultrathin-films by a controlled droplet dragging approach Open
Micropatterning of transition metal dichalcogenide (TMDC) ultrathin-films and monolayers has been demonstrated by various multi-step approaches. However, directly achieving a patterned growth of TMDC films is still considered to be challen…
View article: High-purity free-electron momentum states prepared by three-dimensional optical phase modulation
High-purity free-electron momentum states prepared by three-dimensional optical phase modulation Open
The generation of high-coherence, ultrashort electron pulses, and their manipulation by intense light fields promises new pathways in the active control of free-electron beams. Harnessing the temporal coherence, a broad range of applicatio…
View article: Broadband Coupling of Fast Electrons to High-Q Whispering-Gallery Mode Resonators
Broadband Coupling of Fast Electrons to High-Q Whispering-Gallery Mode Resonators Open
Transmission electron microscopy is an excellent experimental tool to study the interaction of free electrons with nanoscale light fields. However, up to now, applying electron microscopy to quantum optical investigations was hampered by t…
View article: Ultrafast strain propagation and acoustic resonances in nanoscale bilayer systems
Ultrafast strain propagation and acoustic resonances in nanoscale bilayer systems Open
Ultrafast structural probing has greatly enhanced our understanding of the coupling of atomic motion to electronic and phononic degrees-of-freedom in quasi-bulk materials. In bi- and multilayer model systems, additionally, spatially inhomo…