Search results for "photoemission electron"
showing 10 items of 55 documents
Spin structure and spin Hall magnetoresistance of epitaxial thin films of the insulating non-collinear antiferromagnet SmFeO3
2019
We report a combined study of imaging the antiferromagnetic (AFM) spin structure and measuring the spin Hall magnetoresistance (SMR) in epitaxial thin films of the insulating non-collinear antiferromagnet SmFeO$_3$. X-ray magnetic linear dichroism photoemission electron microscopy measurements reveal that the AFM spins of the SmFeO$_3$(110) align in the plane of the film. Angularly dependent magnetoresistance measurements show that SmFeO$_3$/Ta bilayers exhibit a positive SMR, in contrast to the negative SMR expected in previously studied collinear AFMs. The SMR amplitude increases linearly with increasing external magnetic field at higher magnetic field, suggesting that field-induced canti…
Soft X-ray photoelectron microscopy used for the characterization of diamond, a-C and CN , thin films
2002
Abstract This article gives an overview about the application of X-ray photoemission electron microscopy (X-PEEM) used for the analysis of carbon thin films. We present the results of an X-ray absorption near edge structure (XANES) study of CVD diamond, a-C and CNx films on Si (100) as well as a defect analysis of a hard disc scratch test. The sp2/sp3 ratio of the carbon films was determined and mapped in the electron micrographs, which show localized defects in the surface.
Momentum Distribution of Electrons Emitted from Resonantly Excited Individual Gold Nanorods.
2017
Electron emission by femtosecond laser pulses from individual Au nanorods is studied with a time-of-flight momentum resolving photoemission electron microscope (ToF k-PEEM). The Au nanorods adhere to a transparent indium–tin oxide substrate, allowing for illumination from the rear side at normal incidence. Localized plasmon polaritons are resonantly excited at 800 nm with 100 fs long pulses. The momentum distribution of emitted electrons reveals two distinct emission mechanisms: a coherent multiphoton photoemission process from the optically heated electron gas leads to an isotropic emission distribution. In contrast, an additional emission process resulting from the optical field enhanceme…
<title>Miniaturized objective lens for a photoelectron emission microscope</title>
2000
Photoemission electron microscopy (PEEM) has turned out to be one of the most promising methods for surface analysis in the recent years. It is a full field imaging technique based on the emission of secondary electrons by far ultraviolet light or X-rays. The emission intensity of secondary electrons is critically dependent upon the acceptance angle of the incident radiation. However, the size of the microscope restricts this angle substantially. Miniaturizing the objective lens of the microscope reduces the restriction of the acceptance angle and improves the performance of the PEEM considerably. We report on the fabrication of a miniaturized objective lens containing the extraction electr…
At-wavelength inspection of sub-40 nm defects in extreme ultraviolet lithography mask blank by photoemission electron microscopy.
2007
A new at-wavelength inspection technology to probe nanoscale defects buried underneath Mo/Si multilayers on an extreme ultraviolet (EUV) lithography mask blank has been implemented using EUV photoemission electron microscopy (EUV-PEEM). EUV-PEEM images of programmed defect structures of various lateral and vertical sizes recorded at an ~13.5 nm wavelength show that 35 nm wide and 4 nm high buried line defects are clearly detectable. The imaging technique proves to be sensitive to small phase jumps, enhancing the edge visibility of the phase defects, which is explained in terms of a standing wave enhanced image contrast at resonant EUV illumination.
Actinic inspection of sub-50 nm EUV mask blank defects
2007
A new actinic mask inspection technology to probe nano-scaled defects buried underneath a Mo/Si multilayer reflection coating of an Extreme Ultraviolet Lithography mask blank has been implemented using EUV Photoemission Electron Microscopy (EUV-PEEM). EUV PEEM images of programmed defect structures of various lateral and vertical sizes recorded at around 13 nm wavelength show that 35 nm wide and 4 nm high buried line defects are clearly detectable. The imaging technique proves to be sensitive to small phase jumps enhancing the visibility of the edges of the phase defects which is explained in terms of a standing wave enhanced image contrast at resonant EUV illumination.
Inspection of EUVL mask blank defects and patterned masks using EUV photoemission electron microscopy
2008
We report on recent developments of an "at-wavelength" full-field imaging technique for inspection of multilayer mask blank defects and patterned mask samples for extreme ultraviolet lithography (EUVL) by EUV photoemission electron microscopy (EUV-PEEM). A bump-type line defect with a width of approximately 35nm that is buried beneath Mo/Si multilayer has been detected clearly, and first inspection results obtained from a patterned TaN absorber EUVL mask sample is reported. Different image contrast of a similar width of multilayer-covered substrate line defect and on top TaN absorber square has been observed in the EUV-PEEM images, and origin of the difference in their EUV-PEEM image contra…
Time-resolved photoemission electron microscopy
2009
The excellent time structure of Synchrotron radiation and short-pulse lasers has opened the door to a novel way of time-resolved imaging using PEEM. Periodic or repetitive processes can be studied by stroboscopic illumination with the pulsed photon beam. Since the first experiments in 2003, two fields of applications have been established in several groups. One concerns the investigation of fast magnetisation processes like precessional switching, Gigahertz-eigenmodes of ferromagnetic nanostructures or travelling spin waves in thin films. More recently, femtosecond lasers have been used for imaging of localised surface plasmons in nanoparticles and their temporal behaviour in the femtosecon…
Photoemission Electron Microscopy as a tool for the investigation of optical near fields
2005
Photoemission electron microscopy was used to image the electrons photoemitted from specially tailored Ag nanoparticles deposited on a Si substrate (with its native oxide SiO$_{x}$). Photoemission was induced by illumination with a Hg UV-lamp (photon energy cutoff $\hbar\omega_{UV}=5.0$ eV, wavelength $\lambda_{UV}=250$ nm) and with a Ti:Sapphire femtosecond laser ($\hbar\omega_{l}=3.1$ eV, $\lambda_{l}=400$ nm, pulse width below 200 fs), respectively. While homogeneous photoelectron emission from the metal is observed upon illumination at energies above the silver plasmon frequency, at lower photon energies the emission is localized at tips of the structure. This is interpreted as a signat…
Femtosecond time-resolved photoemission electron microscopy operated at sample illumination from the rear side
2019
We present an advanced experimental setup for time-resolved photoemission electron microscopy (PEEM) with sub-20 fs resolution, which allows for normal incidence and highly local sample excitation with ultrashort laser pulses. The scheme makes use of a sample rear side illumination geometry that enables us to confine the sample illumination spot to a diameter as small as 6 μm. We demonstrate an operation mode in which the spatiotemporal dynamics following a highly local excitation of the sample is globally probed with a laser pulse illuminating the sample from the front side. Furthermore, we show that the scheme can also be operated in a time-resolved normal incidence two-photon PEEM mode w…