Effects of Periodic Structures on the Coherence Properties of Blackbody Radiation

2004 ◽  
Vol 126 (5) ◽  
pp. 786-792 ◽  
Author(s):  
L. Hu ◽  
A. Schmidt ◽  
A. Narayanaswamy ◽  
G. Chen
Keyword(s):  
Ray Tracing ◽  
Layer Thickness ◽  
Periodic Structures ◽  
Blackbody Radiation ◽  
Radiative Properties ◽  
Multilayer Structures ◽  
Wave Optics ◽  
Wave Interference ◽  
Radiation Sources ◽  
Random Structures

Radiative properties have been studied for one-dimensional dielectric multilayer structures subjected to blackbody radiation sources. The total hemispherical transmittances are calculated for periodic structures and structures with random variation in layer thickness, using wave-optics and ray-tracing methods. Simulation results show that for periodic structures, the transmittance calculated using wave optics approaches a nonzero constant value with an increasing number of layers, while the transmittance obtained using the ray-tracing method asymptotically approaches zero. For random structures, the transmittance given by wave optics drops to zero at different rates depending on the order of random variations in layer thickness. It is found that the wave interference effect always plays a role when dealing with multilayer structures. The results are explained based on extended and localized waves.

scholarly journals Assessment of Potential of the High-Voltage Anodic Plasma Source to Deposit Multilayer Structures Relevant to X-ray Mirror Applications

Coatings ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 531
Author(s):  
Aurel-Mihai Vlaicu ◽  
Alexandru Anghel ◽  
Marius Badulescu ◽  
Cristina Surdu-Bob
Keyword(s):  
Film Thickness ◽  
Layer Thickness ◽  
Deposition Rate ◽  
High Voltage ◽  
Plasma Source ◽  
Multilayer Structures ◽  
Deposition Technique ◽  
X Ray ◽  
Coating Technique ◽  
Glass Substrates

(1) Background: The high-voltage anodic-plasma (HVAP) coating technique has a series of specificities that are not simultaneously met in other deposition methods. This paper aimed at assessing the potential of HVAP to synthesize quality multilayers for X-ray optics. (2) Methods: Nanolayers of W, Ta, B, and Si were deposited as mono-, bi-, and multilayers onto very smooth glass substrates by HVAP, and their thickness and density were analyzed by X-ray reflectometry. The minimal film thickness needed to obtain continuous nanolayers was also investigated. (3) Results: Nanolayer roughness did not increase with layer thickness, and could be lowered via deposition rate, with values as low as 0.6 for the W nanolayer. Minimal film thickness for continuous films for the studied metals was 4 nm (W), 6 nm (Ta), 2.5 nm (B), and 6 nm (Si). (4) Conclusions: The investigation revealed the range of parameters to be used for obtaining quality nanolayers and multilayers by HVAP. Advantages and possible improvements are discussed. This deposition technique can be tailored for demanding applications such as X-ray mirrors.

Total and spectral radiance measurements of blackbody radiation sources based on an absolute cryogenic radiometer

2019 ◽  
Author(s):  
Haiyong Gan ◽  
Nan Xu ◽  
Xiangliang Liu ◽  
Yingwei He ◽  
Houping Wu ◽  
...  
Keyword(s):  
Blackbody Radiation ◽  
Spectral Radiance ◽  
Cryogenic Radiometer ◽  
Radiation Sources

Growth and Fractal Structure of Ceramic Precursors

MRS Bulletin ◽  
1987 ◽  
Vol 12 (7) ◽  
pp. 29-33 ◽  
Author(s):  
Keith D. Keefer
Keyword(s):  
Periodic Structures ◽  
Dense Body ◽  
Chemical Constituents ◽  
Ceramic Materials ◽  
Growth Processes ◽  
Crystalline Materials ◽  
Special Cases ◽  
Random Structures ◽  
Ceramic Precursors ◽  
Random Growth

Ceramic precursors are the chemical constituents of ceramic materials in a form in which they can be manipulated and shaped prior to processing to form a dense body. Generally these precursors are finely ground crystalline materials such as oxides or clays. Recently, however, much effort has focused on preparing precursors by chemical rather than mechanical means. The goal is to prepare purer, more homogeneous, and more reactive precursors than mixed crystalline powders. A wide variety of chemical processes have been devised to grow ceramic precursors, including powders formed by precipitation reactions, gels formed by hydrolysis and condensation reactions, and gas phase pyrolysis, to name just a few. Due to the random nature of the growth processes, these precursors often have structures wholly unlike their mechanically derived counterparts on both an atomic and a “macromolecular” scale. Random growth and structure and the effect of these structures on the subsequent processing of ceramics is an area of growing interest.Random structures are inherently more difficult to describe and study than are the ordered, periodic structures of crystals. With the exception of a few special cases, such as random walk polymers, little of a quantitative nature could be said about them until the development of fractal geometry and the accompanying realization that the structures which result from many random growth processes are, in fact, fractal.

Investigation of Ti Layer Thickness Dependent Structural, Magnetic, and Photoemission Study of Nanometer Range Ti/Ni Multilayer Structures

2007 ◽  
Vol 7 (6) ◽  
pp. 2081-2086 ◽  
Author(s):  
Pramod Bhatt ◽  
Ram Prakash ◽  
S. M. Chaudhari ◽  
V. R. Reddy ◽  
D. M. Phase
Keyword(s):  
Layer Thickness ◽  
Multilayer Structures ◽  
Nanometer Range ◽  
Photoemission Study

Uniform Low-Temperature Deposition of Optical Layers by Plasma-Activated CVD

1992 ◽  
Vol 269 ◽  
Author(s):  
Hans Lydtin ◽  
Arnd Ritz
Keyword(s):  
Low Temperature ◽  
Layer Thickness ◽  
Operation Mode ◽  
Plasma Source ◽  
Multilayer Structures ◽  
Dielectric Layers ◽  
Remote Operation ◽  
Temperature Deposition ◽  
Microwave Applicator ◽  
Materials Used

ABSTRACTPlasma activated CVD in a remote operation mode is applied to the deposition of dielectric layers on extended substrates. Layer thickness uniformity of ±1% over areas of 80mm diameter is demonstrated. The microwave applicator sustaining the plasma source of condensable species is compared in its deposition characteristic to conventional evaporation sources. Deposition efficiencies up to 70% are reached. The layer materials used are SiO2 and TiO2. Multilayer structures are prepared and optically characterized.

Freezing-point-blackbody radiation sources for the 2978–108462 °C temperature range

1996 ◽  
Vol 35 (13) ◽  
pp. 2211 ◽  
Author(s):  
Allan Ghaemi
Keyword(s):  
Freezing Point ◽  
Blackbody Radiation ◽  
Temperature Range ◽  
Radiation Sources

Radiative Properties of Pattered Wafers With Linewidth Below 100 nm

2005 ◽  
Author(s):  
Y.-B. Chen ◽  
Z. M. Zhang ◽  
P. J. Timans
Keyword(s):  
Periodic Structures ◽  
Numerical Study ◽  
Radiative Properties ◽  
Angle Of Incidence ◽  
Patterned Wafers ◽  
Rigorous Coupled Wave Analysis ◽  
Recent Developments ◽  
Effective Medium Approach ◽  
Rigorous Coupled Wave ◽  
Very High

Temperature nonuniformity is a critical problem in rapid thermal processing (RTP) of wafers because it leads to uneven diffusion of implanted dopants and introduces thermal stress that can produce defects. One cause of the problem is nonuniform absorption of thermal radiation, especially in patterned wafers, where the optical properties vary across the surface of the wafer. Recent developments in RTP have lead to the use of millisecond-duration heating cycles, where light with very high power density is used to heat the surface of the wafer. Pattern effects are especially important here, because there is very little time for thermal diffusion to even out temperature distributions during the heating cycle. There have been very few studies on the radiative properties of patterned wafers, especially for the structures expected to be used on advanced semiconductor devices. The feature size is already below 100 nm and is comparable or smaller than the wavelengths of radiation (200–1000 nm) emitted by the flash-lamps typically used for millisecond processing. Hence, this work is devoted to a parametric numerical study of the radiative properties of patterned wafers with the smallest dimension down to 30 nm. The effects of wavelength, wave polarization, and angle of incidence on selected periodically patterned wafers are presented. The methods include the rigorous coupled wave analysis (RCWA) and the effective medium approach (EMA). RCWA is used to obtain exact solutions of Maxwell’s equations, and EMA is used to approximate the periodic structures as a planar multilayer structure with an effective dielectric function. This study provides an assessment of the applicability of EMA for simulations of radiative properties of patterned wafers.

Retrieval of Uniaxial Permittivity and Permeability for the Study of Near-Field Radiative Transport Between Metallic Nanowire Arrays

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Jui-Yung Chang ◽  
Payam Sabbaghi ◽  
Yu-Shao Weng ◽  
Yu-Bin Chen ◽  
Liping Wang
Keyword(s):  
Magnetic Permeability ◽  
Effective Medium Theory ◽  
Near Field ◽  
Nanowire Arrays ◽  
Radiative Properties ◽  
Electric Permittivity ◽  
Medium Theory ◽  
Wave Interference ◽  
Guided Mode ◽  
Magnetic Resonances

Abstract Recently metamaterials made of periodic nanowire arrays, multilayers, and grating structures have been studied for near-field thermal radiation with enhanced coupling of evanescent waves due to surface plasmon/phonon polariton, hyperbolic mode, epsilon-near-zero and epsilon-near-pole (ENP) modes, guided mode, and wave interference. In this work, both effective uniaxial electric permittivity and magnetic permeability of a nanowire-based metamaterial are retrieved theoretically through the far-field radiative properties obtained by finite difference time-domain (FDTD) simulations. The artificial magnetic response of metamaterials, which cannot be obtained by traditional effective medium theory (EMT) based on electric permittivity of constitutes only, is successfully captured by the nonunity magnetic permeability, whose resonant frequency is verified by an inductor-capacitor model. By incorporating the retrieved electric permittivity and magnetic permeability into fluctuational electrodynamics with multilayer uniaxial wave optics, the near-field radiative heat transfer between the metallic nanowire arrays is theoretically studied and spectral near-field heat enhancements are found for both transverse electric and magnetic waves due to artificial magnetic resonances. The understanding and insights obtained here will facilitate the application of metamaterials in near-field radiative transfer.

Overview Of Blackbody Radiation Sources

1982 ◽  
Author(s):  
Arthur J. Cussen
Keyword(s):  
Blackbody Radiation ◽  
Radiation Sources
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