Dielectric Tensor Characterization for Overcoated Amorphous TbFe Alloys

1986 ◽  
Vol 80 ◽  
Author(s):  
M. Ruane ◽  
A. Jain ◽  
R. Rosenvold ◽  
M. Mansuripur
Keyword(s):  
Protective Layer ◽  
Estimation Algorithm ◽  
Optical Signal ◽  
Dielectric Tensor ◽  
Amorphous Thin Films ◽  
Sputter Deposited ◽  
Reflectivity Data ◽  
Quartz Substrates ◽  
Optical Behavior ◽  
Made In

AbstractAmorphous thin films of TbFe. sputter-deposited on quartz substrates with compositions supporting polar Kerr magneto-optical behavior, and overcoated with a transparent protective layer, are studied to determine their dielectric tensor elements. Refleetivity measurements over a range of angles of incidence are made in an apparatus that corrects for the overcoat layer and exploits magnetization reversal to enhance the measurement of r⊥, the complex reflectivity associated with the magneto-optical signal. Conventional Fresnel reflectivities are also found. The theoretical model for reflectivities from a thick film magneto-optical medium at oblique incidenci is developed and used within a Levenberg-Marquardt nonlinear estimation algorithm to estimate sequentially the dielectric tensor elements, considering their widely varying magnitudes and sensitivities to errors in reflectivity data. The interpretation of the dielectric elements in terms of magneto-optical performance and structural perpendicular anisotropy is discussed.

Ellipsometric Characterization for Multilayers Containing Magneto-Optic TbFeCo Films

1987 ◽  
Vol 103 ◽  
Author(s):  
M. Ruane ◽  
A. Jain
Keyword(s):  
Optical Activity ◽  
Optical Signal ◽  
Optically Active ◽  
Index Of Refraction ◽  
Dielectric Tensor ◽  
Angle Of Incidence ◽  
Multilayered Structures ◽  
Kerr Rotation ◽  
Ellipsometric Characterization ◽  
Sputter Deposited

ABSTRACTMultilayered structures containing sputter-deposited films of amorphous TbFeCo can exhibit magneto-optical Kerr rotation and are leading candidates for erasable optical storage media. Ellipsometric characterization of optically active multilayered media is desirable during media development, testing and production, but traditional ellipsometry does not account for the presence of optical activity. A novel ellipsometer is described that can characterize both the dielectric overcoat and the optically active layers. Reflectivity measurements are collected for different incident angles and polarizations using a differential detector while the magnetic reversibility of the active film layer is exploited to enhance the magneto-optical signal from the TbFeCo. A multilayer film model is used to process observations and estimate media characteristics. The model explicitly accounts for the optical activity of the TbFeCo layer, and is parameterized in terms of the index of refraction and thickness of the overcoat, and the real and imaginary parts of the elements of the dielectric tensor of the active layer.A series of TbFeCo films with varying composition, rf-sputter deposited on quartz substrates with Al2O3 dielectric protective overcoats, is characterized. Both Tb-rich and Fe-rich samples were deposited, with room temperature coercivities ranging from 1.6kOe to about 4kOe, and film-side Kerr rotations between 21 minutes and 28 minutes. Reflectivity data versus angle of incidence, and estimated dielectric tensor elements for the TbFeCo layers are presented. A standard figure of merit, based on the off-diagonal tensor elements, is used to compare competing media in terms of their optimal performance in a multilayered structure.

Optical Behavior of Sputter-Deposited Aluminum Nitride: Relationship to Film Cheiistry

1985 ◽  
Vol 47 ◽  
Author(s):  
C. J. G. Kubiak ◽  
C. R. Aita ◽  
F. S. Hickernell ◽  
S. J. Joseph
Keyword(s):  
Aluminum Nitride ◽  
Sputter Deposition ◽  
Aluminum Target ◽  
Reactive Sputter Deposition ◽  
Sputter Deposited ◽  
Excited Nitrogen ◽  
Amorphous Quartz ◽  
Quartz Substrates ◽  
Optical Behavior

ABSTRACTFilms which are nominally aluminum nitride were grown by reactive sputter deposition using an aluminum target and rf-excited nitrogen discharges operated at power levels from 100 to 800W. Depositions were made on water-cooled (111)-cut Si and amorphous quartz substrates. The optical behavior of these films and its relationship to chemistry is discussed in the present paper.

Quantifying Optical Tip-Timing Probe Error With Laboratory Apparatus

2011 ◽  
Author(s):  
Bruce D. Hockaday
Keyword(s):  
Arrival Time ◽  
Optical Signal ◽  
Data Conversion ◽  
Time Of Arrival ◽  
Optical Probes ◽  
Engine Operation ◽  
Timing Resolution ◽  
Blade Tip ◽  
Dynamic Errors ◽  
Made In

Detection of airfoil time of arrival with optical probes has been evolving since the 1980s. Time of arrival data are used to infer airfoil stresses caused by vibration through a sequence of manipulations. The data conversion begins by converting arrival time to blade position, so blade deflection can be determined from the expected non-vibrating position. Various methods are used in the industry to convert deflection data to frequency, amplitude, and stress, which is beyond the scope of this paper. Regardless of the analytical approach used, producing accurate stress information relies on the precise detection and measurement of time of arrival, which equates to blade position. Recent improvements have been made in time of arrival system accuracy by running faster clocks to increase temporal resolution of the measurement. Greater timing resolution, afforded by clock speed, will have diminishing returns when probe and blade-tip interactions begin producing dominant errors. In the case of optical probes, the blade-tip needs to be treated as a curved reflector in the optical system that is capable of introducing dynamic errors. In engine operation the blade-tip moves axially under the probe from untwist, static deflection, and vibration, causing the light to reflect from different parts of the blade-tip. This relative movement between the probe and blade-tip cause the arrival time to change dynamically. Neglecting the dynamic arrival errors caused by the blade-tip’s optical properties will result in blade deflection-errors that propagate into the stress information. This paper presents a laboratory study that quantifies time of arrival errors due to optical interaction with tip radii. The study reports measured arrival position error as a function of location and optical signal power levels. The work is presented in terms of arrival position, producing information that is independent of rotational speed, and vibratory mode.

Influence of spin orbit splitting and satellite transitions on nickel soft X-ray optical properties near its L 2,3 absorption edge region

2020 ◽  
Vol 27 (6) ◽  
pp. 1633-1639
Author(s):  
Kiranjot ◽  
Mohammed H. Modi ◽  
Raj Kumar Gupta ◽  
Mangalika Sinha ◽  
Praveen Kumar Yadav
Keyword(s):  
Absorption Spectra ◽  
Ion Beam ◽  
Optical Spectra ◽  
Edge Region ◽  
Transition Elements ◽  
Orbit Splitting ◽  
Spin Orbital ◽  
X Ray ◽  
Sputter Deposited ◽  
Reflectivity Data

Transition elements exhibit strong correlations and configuration interactions between core and valence excited states, which give rise to different excitations inside materials. Nickel exhibits satellite features in its emission and absorption spectra. Effects of such transitions on the optical constants of nickel have not been reported earlier and the available database of Henke et al. does not represent such fine features. In this study, the optical behaviour of ion beam sputter deposited Ni thin film near the L 2,3-edge region is investigated using reflection spectroscopy techniques, and distinct signatures of various transitions are observed. The soft X-ray reflectivity measurements in the 500–1500 eV photon energy region are performed using the soft X-ray reflectivity beamline at the Indus-2 synchrotron radiation source. Kramers–Kronig analysis of the measured reflectivity data exhibit features corresponding to spin orbital splitting and satellite transitions in the real and imaginary part of the refractive index (refraction and absorption spectra). Details of fine features observed in the optical spectra are discussed. To the best of our knowledge, this is the first study reporting fine features in the measured optical spectra of Ni near its L 2,3-edge region.

Sol-Gel Protective Films for Metal Solar Mirrors

1988 ◽  
Vol 121 ◽  
Author(s):  
Scott Reed ◽  
Carol Ashley
Keyword(s):  
Protective Coatings ◽  
Sol Gel ◽  
Protective Layer ◽  
Front Surface ◽  
Optical Measurements ◽  
Preliminary Evaluation ◽  
Environmental Testing ◽  
Specular Reflectance ◽  
Outdoor Environments ◽  
Sputter Deposited

ABSTRACTFront-surface metal mirrors were coated with a variety of sol-gel derived glass films for preliminary evaluation as protective coatings for silver. Optical measurements (hemispherical, diffuse and specular reflectance) were used to characterize changes in the mirror resulting from the application of the sol, subsequent processing, or environmental testing. The abrasion resistance of the films was determined on sol-gel coated silicon wafers per ASTM procedures. The mirrors were exposed to outdoor environments in Albuquerque, N.M., as well as accelerated testing in H2SO4, with periodic monitoring of optical properties. A two layer coating scheme, consisting of a thin primary protective layer of sputter deposited SiO2 followed by a thicker sol-gel overcoat, was also evaluated.

Structural characterization of sputter-deposited LaNiO3 thin films on Si substrate by x-ray reflectivity and diffraction

1997 ◽  
Vol 12 (11) ◽  
pp. 3165-3173 ◽  
Author(s):  
Hsin-Yi Lee ◽  
Tai-Bor Wu
Keyword(s):  
Thin Films ◽  
Transition Layer ◽  
Mass Density ◽  
Composition Analysis ◽  
X Ray Diffraction ◽  
Diffraction Intensity ◽  
Si Substrate ◽  
X Ray ◽  
Sputter Deposited ◽  
Reflectivity Data

X-ray reflectivity and diffraction were applied to characterize the highly (100)-textured thin films of LaNiO3, which were deposited on Si substrate via radio frequency magnetron sputtering at temperatures ranging from 250 to 450 °C. Two interference fringes of different period were observed from the reflectivity curves, and the fitting result indicates that in addition to the normal lanthanum-nickel oxide layer, a transition layer, which has a larger mass density than the previous one, exists in the sputter-deposited films. A comparison of the measured x-ray diffraction intensity with that calculated from layer thickness and mass density obtained from reflectivity data indicates that the transition layer is noncrystalline. The x-ray diffraction result also shows that there is a significant decrease of (100) diffraction intensity relative to that of (200) as increasing the deposition temperature. Using the reflectivity and diffraction data along with results of electron diffraction and film composition analysis from our other studies, such a change of relative intensity between the two diffraction peaks is attributed to the increasing content of two also highly textured La-rich phases, i.e., (110)-textured La4Ni3O10 and (100)-textured La2NiO4, in addition to the LaNiO3.

Near‐band gap optical behavior of sputter deposited α‐ and α+β‐ZrO2films

1989 ◽  
Vol 66 (6) ◽  
pp. 2756-2758 ◽  
Author(s):  
Chee‐Kin Kwok ◽  
Carolyn Rubin Aita
Keyword(s):  
Band Gap ◽  
Sputter Deposited ◽  
Optical Behavior

Interfacial Reactions of Refractory Metals Niobium and Tantalum with Ceramics Silicon Carbide and Alumina

1989 ◽  
Vol 170 ◽  
Author(s):  
A. Joshl ◽  
H. S. Hu ◽  
J. Wadsworth
Keyword(s):  
Silicon Carbide ◽  
Ternary Phase ◽  
Depth Profiling ◽  
Interfacial Reactions ◽  
Matrix Composites ◽  
Sapphire Substrates ◽  
Polycrystalline Silicon Carbide ◽  
Sputter Deposited ◽  
Strength And Ductility ◽  
Made In

AbstractRecent interest in the development of advanced metal matrix composites has prompted research on interfacial reactions of Nb and Ta with candidate reinforcements such as silicon carbide and alumina. Formation of reaction layers as small as 0.1 μm can be detrimental to composite strength and ductility and in some instances to the corrosion behavior, which suggests the importance of understanding the early stages of interfacial reactions. Thin films of Nb and Ta were sputter deposited on single crystal and polycrystalline silicon carbide and on sapphire substrates, and the nature and extent of reaction evahiated using Auger depth profiling and electron microscopy. In the Nb/SiC system, NbCX is the first reaction product to form, but the overall extent of the reaction is dominated by the formation of the more stable NbCXSiY ternary phase. Little or no interfacial reaction was observed in the Nb/Al2O3 system for up to 4 hburs at 1100°C, which also suggests that Al2O3 may be a potential diffusion barrier to minimize reactions in the Nb/SiC system. Similar interesting observations were made in the Ta/SiC and Ta/Al2O3 systems.

Surface Protection during Plasma Hydrogenation for Acceptor Passivation in InP

1989 ◽  
Vol 163 ◽  
Author(s):  
J. Lopata ◽  
W. C. Dautremont-Smith ◽  
S. J. Pearton ◽  
J. W. Lee ◽  
N. T. Ha ◽  
...  
Keyword(s):  
Depth Profiling ◽  
Protective Layer ◽  
Coated Sample ◽  
Dielectric Films ◽  
Wafer Surface ◽  
Plasma Exposure ◽  
Surface Protection ◽  
P Loss ◽  
Inp Substrate ◽  
Sputter Deposited

AbstractVarious dielectric and metallic films were examined as H-permeable surface protection layers on InP during H2 or D2 plasma exposure for passivation of acceptors in the InP. Plasma deposited SiNx, SiO2, and a-Si(H) films ranging in thickness from 85 to 225 Å were used to protect p-InP during D2 plasma exposure at 250°C. Optimum protective layer thicknesses were determined by a trade-off between the effectiveness of the layer to prevent P loss from the wafer surface and the ability to diffuse atomic H or D at a rate greater than or equal to that in the underlying InP. SIMS and capacitance-voltage depth profiling were used to determine the extent of D in-diffusion and acceptor passivation respectively. Sputter deposited W and e-beam evaporated Ti films ~100 Å thick were also evaluated. The W coated sample yielded similar results to those with dielectric films in that acceptors in p-InP were passivated to a similar depth for the same plasma exposure. The 100 Å Ti film, however, did not allow the D to diffuse into the InP substrate. It is surmised that the Ti film trapped the D, thus preventing diffusion into the substrate.

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