30 research outputs found
Light emission from silicon with tin-containing nanocrystals
Tin-containing nanocrystals, embedded in silicon, have been fabricated by
growing an epitaxial layer of Si_{1-x-y}Sn_{x}C_{y}, where x = 1.6 % and y =
0.04 %, followed by annealing at various temperatures ranging from 650 to 900
degrees C. The nanocrystal density and average diameters are determined by
scanning transmission-electron microscopy to ~ 10^{17} cm^{-3} and ~ 5 nm,
respectively. Photoluminescence spectroscopy demonstrates that the light
emission is very pronounced for samples annealed at 725 degrees C, and
Rutherford back-scattering spectrometry shows that the nanocrystals are
predominantly in the diamond-structured phase at this particular annealing
temperature. The origin of the light emission is discussed.Comment: 5 pages, 3 figures, submitted to AIP Advance
Tuning the plasmon resonance of metallic tin nanocrystals in Si-based materials
The optical properties of metallic tin nanoparticles embedded in
silicon-based host materials were studied. Thin films containing the
nanoparticles were produced using RF magnetron sputtering followed by ex situ
heat treatment. Transmission electron microscopy was used to determine the
nanoparticle shape and size distribution; spherical, metallic tin nanoparticles
were always found. The presence of a localized surface plasmon resonance in the
nanoparticles was observed when SiO2 and amorphous silicon were the host
materials. Optical spectroscopy revealed that the localized surface plasmon
resonance is at approximately 5.5 eV for tin nanoparticles in SiO2, and at
approximately 2.5 eV in amorphous silicon. The size of the tin nanoparticles in
SiO2 can be varied by changing the tin content of the films; this was used to
tune the localized surface plasmon resonance.Comment: 14 pages, 7 figure
Ion-Beam-Induced Atomic Mixing in Ge, Si, and SiGe, Studied by Means of Isotope Multilayer Structures
Crystalline and preamorphized isotope multilayers are utilized to investigate the dependence of ion beam mixing in silicon (Si), germanium (Ge), and silicon germanium (SiGe) on the atomic structure of the sample, temperature, ion flux, and electrical doping by the implanted ions. The magnitude of mixing is determined by secondary ion mass spectrometry. Rutherford backscattering spectrometry in channeling geometry, Raman spectroscopy, and transmission electron microscopy provide information about the structural state after ion irradiation. Different temperature regimes with characteristic mixing properties are identified. A disparity in atomic mixing of Si and Ge becomes evident while SiGe shows an intermediate behavior. Overall, atomic mixing increases with temperature, and it is stronger in the amorphous than in the crystalline state. Ion-beam-induced mixing in Ge shows no dependence on doping by the implanted ions. In contrast, a doping effect is found in Si at higher temperature. Molecular dynamics simulations clearly show that ion beam mixing in Ge is mainly determined by the thermal spike mechanism. In the case of Si thermal spike, mixing prevails at low temperature whereas ion beam-induced enhanced self-diffusion dominates the atomic mixing at high temperature. The latter process is attributed to highly mobile Si di-interstitials formed under irradiation and during damage annealing
Erbium diffusion in titanium dioxide
The diffusivity of erbium in the anatase phase of titanium dioxide (TiO2) has
been studied for various temperatures ranging from 800 °C to 1, 000 °C. Samples of
TiO2, with a 10 nm thick buried layer containing 0.5 at% erbium, were fabricated by
radio-frequency magnetron sputtering and subsequently heat treated. The erbium concentration profiles
were measured by secondary ion
mass spectrometry, allowing for determination of the
temperature-dependent diffusion coefficients. These were found to follow an Arrhenius law
with an activation energy of
(
2.1
±
0.2
)
eV. X-ray diffraction revealed that the TiO2 films consisted of
polycrystalline grains of size ≈ 100 nm
Structural characterization of tin nanocrystals embedded in silicon by atomic probe tomography
International audienceTin nanocrystals embedded in silicon are studied by atom probe tomography and by photoluminescence spectroscopy in the 0.76–1.07 eV region of emission energies. The nanocrystals have been fabricated by molecular beam epitaxy followed by a post-growth annealing step at various temperatures. One particular sample, annealed at a temperature of 725 °C, shows a distinctly higher optical activity. It is found, however, that the distinct behavior cannot be explained by variations in the nanocrystal composition or in the properties of Sn atoms dissolved in the surrounding Si matrix, which can be investigated by atom probe tomography
Structural characterization of tin nanocrystals embedded in silicon by atomic probe tomography
International audienceTin nanocrystals embedded in silicon are studied by atom probe tomography and by photoluminescence spectroscopy in the 0.76–1.07 eV region of emission energies. The nanocrystals have been fabricated by molecular beam epitaxy followed by a post-growth annealing step at various temperatures. One particular sample, annealed at a temperature of 725 °C, shows a distinctly higher optical activity. It is found, however, that the distinct behavior cannot be explained by variations in the nanocrystal composition or in the properties of Sn atoms dissolved in the surrounding Si matrix, which can be investigated by atom probe tomography
Light emission from silicon containing Sn-nanocrystals
International audienceThis work investigates light emission from sili- con with embedded Sn nanocrystals. The composition of the nanocrystals is determined to be pure Sn by atom probe tomog- raphy, and the light emission is strongest when the nanocrystal structure is closest to the host Si lattice diamond structure
Light emission from silicon containing Sn-nanocrystals
International audienceThis work investigates light emission from sili- con with embedded Sn nanocrystals. The composition of the nanocrystals is determined to be pure Sn by atom probe tomog- raphy, and the light emission is strongest when the nanocrystal structure is closest to the host Si lattice diamond structure
Radiation collimation in a thick crystalline undulator
With the recent experimental confirmation of the existence of energetic radiation from a Small Amplitude, Small Period (SASP) crystalline undulator [T.N. Wistisen, K.K. Andersen, S. Yilmaz, R. Mikkelsen, J. Lundsgaard Hansen, U.I. Uggerhøj, W. Lauth, H. Backe, Phys. Rev. Lett. 112, 254801 (2014)], the field of specially manufactured crystals, from which specific radiation characteristics can be obtained, has evolved substantially. In this paper we confirm the existence of the crystalline undulator radiation, using electrons of energies of 855 GeV from the MAinzer MIcrotron (MAMI) in a crystal that is approximately 10 times thicker than the previous one. Furthermore, we have measured a significant increase in enhancement, in good agreement with calculations, of the undulator peak by collimation to angles smaller than the natural opening angle of the radiation emission process, 1 /γ