A5056722976- Laser-Matter Interactions and Applications
- Ion-surface interactions and analysis
- Electron and X-Ray Spectroscopy Techniques
- Advanced Electron Microscopy Techniques and Applications
- Advancements in Photolithography Techniques
- Laser Material Processing Techniques
- Photorefractive and Nonlinear Optics
- Spectroscopy and Quantum Chemical Studies
- Integrated Circuits and Semiconductor Failure Analysis
- Transition Metal Oxide Nanomaterials
- Photoacoustic and Ultrasonic Imaging
- Advanced Chemical Physics Studies
- Semiconductor materials and devices
- Ga2O3 and related materials
- Silicon Nanostructures and Photoluminescence
- Catalysis and Oxidation Reactions
- Photochemistry and Electron Transfer Studies
- Laser-Plasma Interactions and Diagnostics
- Advanced Thermoelectric Materials and Devices
- Neural Networks and Reservoir Computing
- Magneto-Optical Properties and Applications
- Advanced Nanomaterials in Catalysis
- Atomic and Molecular Physics
- Photosynthetic Processes and Mechanisms
- X-ray Spectroscopy and Fluorescence Analysis
ASML (United States)
2023
University of California, Berkeley
2016-2021
Lawrence Berkeley National Laboratory
2017-2018
SLAC National Accelerator Laboratory
2017
Rutgers Sexual and Reproductive Health and Rights
2015
Rutgers, The State University of New Jersey
2014
Abstract Understanding excited carrier dynamics in semiconductors is crucial for the development of photovoltaics and efficient photonic devices. However, overlapping spectral features optical pump-probe spectroscopy often render assignments separate electron hole ambiguous. Here, ultrafast germanium nanocrystalline thin films are directly simultaneously observed by transient absorption extreme ultraviolet at M 4,5 edge. We decompose spectra into contributions electronic state blocking...
Coulomb correlations can manifest in exotic properties solids, but how these be accessed and ultimately manipulated real time is not well understood. The insulator-to-metal phase transition vanadium dioxide (VO2) a canonical example of such correlations. Here, few-femtosecond extreme UV transient absorption spectroscopy (FXTAS) at the M2,3 edge used to track VO2 This technique allows observation bulk material time, follows photoexcitation process both insulating metallic phases, probes...
The metal-oxo M4O4 "cubane" topology is of special significance to the field water oxidation as it represents merging bioinspired structural principles derived from natural photosynthesis with successful artificial catalysts known date. Herein, we directly compare rates oxidation/O2 evolution catalyzed by six cobalt-oxo clusters including Co4O4 cubanes, Co4O4(OAc)4(py)4 and [Co4O4(OAc)2(bpy)4](2+), using common Ru(bpy)3(2+)/S2O8(2-) photo-oxidant assay. At pH 8, first-order rate constants...
Extreme ultraviolet (XUV) transient reflectivity around the germanium ${M}_{4,5}$ edge ($3d$ core-level to valence transition) at 30 eV is advanced obtain dielectric function of crystalline [100] on femtosecond picosecond time scales following photoexcitation by broadband visible-to-infrared (VIS/NIR) pulses. By fitting function, carrier-phonon induced relaxations are extracted for excited carrier distribution. The measurements reveal a hot electron relaxation rate...
Semiconductor alloys containing silicon and germanium are of growing importance for compact highly efficient photonic devices due to their favorable properties direct integration into platforms wide tunability optical parameters. Here, we report the simultaneous energy-resolved probing ultrafast electron hole dynamics in a silicon-germanium alloy with stoichiometry Si0.25Ge0.75 by extreme ultraviolet transient absorption spectroscopy. Probing photoinduced charge carriers at M4,5-edge (∼30...
Excitation of ionic solids with extreme ultraviolet pulses creates localized core-excitons, which in some cases couple strongly to the lattice. Here, core-excitonic states magnesium oxide are studied time domain at Mg $\text{L}_{2,3}$ edge attosecond transient reflectivity spectroscopy. Attosecond trigger excitation these short-lived quasiparticles, whose decay is perturbed by time-delayed near infrared optical pulses. Combined a few-state theoretical model, this reveals that pulse shifts...
Attosecond spectroscopy of materials has provided invaluable insight into light-driven coherent electron dynamics. However, attosecond spectroscopies have so far been focused on weakly-correlated materials. As a result, the behavior strongly-correlated systems is largely unknown at sub- to few-femtosecond timescales, even though it typically realm which electron-electron interactions operate. Here we conduct attosecond-resolved experiments correlated insulator nickel oxide, and compare its...
The thermalization of hot carriers and phonons gives direct insight into the scattering processes that mediate electrical thermal transport. Obtaining rates for both currently requires multiple measurements with incommensurate timescales. Here, transient extreme-ultraviolet (XUV) spectroscopy on silicon 2p core level at 100 eV is used to measure carrier phonon in Si(100) from tens femtoseconds 200 ps following photoexcitation indirect transition {\Delta} valley 800 nm. ground state XUV...
The complex-valued index of refraction germanium in the extreme ultraviolet (XUV) is measured by multi-angle reflectance synchrotron radiation. resulting higher resolution than previously values. It reveals new structures attributed to transitions from 3d-core orbitals Σ5,2c and X5,2c conduction bands. Additionally, it shown that problem total external reflection, which renders measurements insensitive refractive at grazing incidence, can be overcome employing angles incidence away critical angle.
In Peierls-distorted materials, photoexcitation leads to a strongly coupled transient response between structural and electronic degrees of freedom, always measured independently each other. Here we use reflectivity in the extreme ultraviolet quantify both responses photoexcited bismuth single measurement. With help first-principles calculations based on density-functional theory (DFT) time-dependent DFT, real-space atomic motion temperature electrons holes as function time are captured...
We present an extreme ultraviolet (XUV) transient absorption apparatus tailored to attosecond and femtosecond measurements on bulk solid-state thin-film samples, specifically when the sample dynamics are sensitive heating effects. The setup combines methodology for stabilizing sub-femtosecond time-resolution over 48 h techniques mitigating heat buildup in temperature-dependent samples. Single-point beam stabilization pump probe arms periodic time-zero reference described accurate timing...
We developed and implemented an experimental setup for the generation of high-energy high-order harmonics in argon gas nonlinear experiments extreme ultraviolet (XUV) spectral range. High-order were generated by loosely focusing a laser pulse centered around 800 nm into cell filled with phase-matching condition. The wavefront distortions driving corrected deformable mirror, XUV conversion efficiency was significantly improved due to excellent beam profile at focus. A high-damage-threshold...
It has been demonstrated in the past that high fluxes of extreme ultraviolet (XUV) light could be obtained by driving harmonic generation (HHG) with energy lasers.However, peak intensity at focal point a femtosecond laser more than 100 mJ can too for phase-matched HHG gases.We propose method to optimize spatial profile off-focus locations avoid fully ionizing target atoms.The beam before or after depends on wavefront quality and near field distribution.The spot diameter reaches three times...
Attosecond transient reflectivity in the extreme ultraviolet is developed for monitoring band-gap excitation dynamics germanium.The investigations unravel fastest carrierscattering processes on few-femtosecond time scale, and carrier thermalization longer scales.
Oxides of manganese and cobalt have proved to be effective (electro)catalysts for the water oxidation half-reaction in splitting. Recently, research focus has mostly been on developing high surface area morphologies catalysts with specific activity that are potentially easily adaptable photoelectrochemical cells However, it is still not completely understood why these show such intrinsic activity, many amorphous structures, making difficult elucidate structure-function relationships. Using...
The extreme ultraviolet absorption of vanadium dioxide is probed with attosecond transient during a photoinduced phase transition. Measurements reveal an ultrafast rearrangement in the density states suggestive electron correlation and Mott physics.
The photoinduced insulator-to-metal phase transition in vanadium dioxide is experimentally investigated by attosecond transient absorption spectroscopy. Ultrafast changes cover a broad ~20-eV-wide spectral range, emphasizing core spectroscopic access and the importance of electron correlation effects.
Electron-hole dynamics is measured by attosecond transient absorption in silicon-germanium alloy. The germanium atoms act as reporter time-dependent probing the M4,5-edge, revealing electron and hole dynamics, well a new midgap feature.
With the adoption of extreme ultraviolet (EUV) lithography for high-volume production advanced nodes, stochastic variability and resulting failures, both post litho etch, have drawn increasing attention. There is a strong need accurate models edge placement error (SEPE) with direct link to induced failure probability (FP). Additionally, prevent from occurring on wafers, holistic stochastic-aware computational suite products needed, such as mask source optimization (SMO), optical proximity...
Despite being crucial in an optical lithography process, "dose" has remained a relative concept the computational regime. It usually takes form of percentage deviation from pre-identified "nominal condition" under same illumination shape. Dose comparison between different shapes never been rigorously defined and modeled numerical simulation to date. On other hand, exposure-limited nature EUV throughput demands * shape optimized with physical dose impact consciously taken into consideration....
Attosecond transient reflectivity is developed to observe the photoexcitation dynamics in germanium. time-resolved measurements of dielectric function reveal a few-femtosecond collective electronic response time, which renormalizes Coulomb interaction between excited carriers.