Porous silicon for electrical isolation in radio frequency devices: A review
TL;DR: In this article, the authors present all the possible porous silicon substrates, which can be used for RF devices, and the intrinsic electrical properties of porous silicon such as AC electrical conductivity or dielectric constant are also detailed.
Abstract: The increasing expansion of telecommunication applications leads to the integration of complete system-on-chip associating analog and digital processing units. Besides, the passive elements occupy an increasing silicon footprint, compromising circuit scalability and cost. Moreover, passive components’ performances are limited by the proximity of lossy Si substrate and surrounding metallization. Then, obviously, the characteristics of the substrate become crucial for monolithic radio frequency (RF) systems to reach high performances. So, looking for integrated circuit compatible processes, porous silicon (PS) seems to be a promising candidate as it can provide localized isolating regions from various silicon substrates. In this review, we first present all the possible porous silicon substrates, which can be used for RF devices. In particular, we put the emphasis on the etching conditions, leading to high thickness localized PS layers. The intrinsic electrical properties of porous silicon such as AC electrical conductivity or dielectric constant are also detailed, and the results extracted from the literature are commented. Then, we describe the performances of widespread RF devices, that is, inductors or coplanar waveguides. Finally, we describe methodologies used for predicting RF electrical responses of PS isolated devices, based on electromagnetic simulations.
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TL;DR: It was shown that the dielectric parameters of porous Si (dielectric permittivity and loss tangent) in the above frequency range have values similar to those obtained at lower frequencies (1 to 40 GHz).
Abstract: In this work, the dielectric properties of porous Si for its use as a local substrate material for the integration on the Si wafer of millimeter-wave devices were investigated in the frequency range 140 to 210 GHz. Broadband electrical characterization of coplanar waveguide transmission lines (CPW TLines), formed on the porous Si layer, was used in this respect. It was shown that the dielectric parameters of porous Si (dielectric permittivity and loss tangent) in the above frequency range have values similar to those obtained at lower frequencies (1 to 40 GHz). More specifically, for the samples used, the obtained values were approximately 3.12 ± 0.05 and 0.023 ± 0.005, respectively. Finally, a comparison was made between the performance of the CPW TLines on a 150-μm-thick porous Si layer and on three other radiofrequency (RF) substrates, namely, on trap-rich high-resistivity Si (trap-rich HR Si), on a standard complementary metal-oxide-semiconductor (CMOS) Si wafer (p-type, resistivity 1 to 10 Ω.cm) and on quartz. 84.40.-x; 77.22.Ch; 81.05.Rm
44 citations
Cites background from "Porous silicon for electrical isola..."
...These last values are tunable by changing the material structure and morphology [1-6]....
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TL;DR: This review summarizes the leading advancements in porous silicon (PSi) optical-biosensors, achieved over the past five years, and the approaches that are commonly employed to chemically stabilize and functionalize the PSi surface are described.
Abstract: This review summarizes the leading advancements in porous silicon (PSi) optical-biosensors, achieved over the past five years. The cost-effective fabrication process, the high internal surface area, the tunable pore size, and the photonic properties made the PSi an appealing transducing substrate for biosensing purposes, with applications in different research fields. Different optical PSi biosensors are reviewed and classified into four classes, based on the different biorecognition elements immobilized on the surface of the transducing material. The PL signal modulation and the effective refractive index changes of the porous matrix are the main optical transduction mechanisms discussed herein. The approaches that are commonly employed to chemically stabilize and functionalize the PSi surface are described.
38 citations
TL;DR: The promising characteristics of PSiNPs encourage further exploration for biomedical research and translational medical platforms, particularly in biomedical imaging.
Abstract: Porous silicon nanoparticles (PSiNPs) have attracted increasing interest as biomedical probes for drug delivery and imaging. In particular, a set of unique properties including biodegradability, intrinsic photoluminescence, and favorable mesoporous structure providing high drug loading allow PSiNPs to address current challenges of translational nanomedicine. In this review, the important features of PSiNPs considered as a biomedical imaging probe will be concisely discussed along with recent advances in fabrication and theranostic applications. Firstly, an overview of PSiNP fabrication with controllable geometry through top-down or bottom-up strategies is provided. Next, intrinsic photoluminescence, the key element allowing application of PSiNPs as an imaging agent, is highlighted with near-infrared emission and micro-second scale lifetime. Emerging technologies for biodegradable nanomedicine based on PSiNPs are then presented. Advances of PSiNPs for disease treaments including photodynamic and photothermal therapeutics are also discussed to open up potential translational medical strategies. In addition, the versatile surface chemistry and modification of PSiNPs in the context of biomedical applications are extensively discussed. Overall, the promising characteristics of PSiNPs encourage further exploration for biomedical research and translational medical platforms, particularly in biomedical imaging.
37 citations
TL;DR: Graphene oxide-ordered mesoporous silica materials showed a highly efficient adsorption of heavy metals from wastewater and the removal efficiencies for As, Cd, Cr, Hg, and Pb reached 97.7%, 96.9, 96.0, 98.5%, and 78.7% as discussed by the authors.
34 citations
TL;DR: In this article, the morphological parameters of porous silicon layers (PSL) using spectroscopic ellipsometry from UV to mid-infrared optical range were evaluated using an optical and an infrared ellipsometer with a wide spectral range.
18 citations
References
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TL;DR: Mise au point comportant des definitions generales et la terminologie, la methodologie utilisee, les procedes experimentaux, les interpretations des donnees d'adsorption, les determinations de l'aire superficielle, and les donnes sur la mesoporosite et la microporosite.
Abstract: Mise au point comportant des definitions generales et la terminologie, la methodologie utilisee, les procedes experimentaux, les interpretations des donnees d'adsorption, les determinations de l'aire superficielle, et les donnees sur la mesoporosite et la microporosite
20,347 citations
Abstract: Maxwell's equations are replaced by a set of finite difference equations. It is shown that if one chooses the field points appropriately, the set of finite difference equations is applicable for a boundary condition involving perfectly conducting surfaces. An example is given of the scattering of an electromagnetic pulse by a perfectly conducting cylinder.
14,070 citations
TL;DR: Numerical experiments and numerical comparisons show that the PML technique works better than the others in all cases; using it allows to obtain a higher accuracy in some problems and a release of computational requirements in some others.
9,875 citations
Book•
01 Jan 1968
TL;DR: This first book to explore the computation of electromagnetic fields by the most popular method for the numerical solution to electromagnetic field problems presents a unified approach to moment methods by employing the concepts of linear spaces and functional analysis.
Abstract: From the Publisher:
"An IEEE reprinting of this classic 1968 edition, FIELD COMPUTATION BY MOMENT METHODS is the first book to explore the computation of electromagnetic fields by the most popular method for the numerical solution to electromagnetic field problems. It presents a unified approach to moment methods by employing the concepts of linear spaces and functional analysis. Written especially for those who have a minimal amount of experience in electromagnetic theory, this book illustrates theoretical and mathematical concepts to prepare all readers with the skills they need to apply the method of moments to new, engineering-related problems.Written especially for those who have a minimal amount of experience in electromagnetic theory, theoretical and mathematical concepts are illustrated by examples that prepare all readers with the skills they need to apply the method of moments to new, engineering-related problems."
6,593 citations
TL;DR: A large amount of work world wide has been directed towards obtaining an understanding of the fundamental characteristics of porous Si as mentioned in this paper, and the key importance of crystalline Si nanostructures in determining the behaviour of porous si is highlighted.
Abstract: A large amount of work world-wide has been directed towards obtaining an understanding of the fundamental characteristics of porous Si. Much progress has been made following the demonstration in 1990 that highly porous material could emit very efficient visible photoluminescence at room temperature. Since that time, all features of the structural, optical and electronic properties of the material have been subjected to in-depth scrutiny. It is the purpose of the present review to survey the work which has been carried out and to detail the level of understanding which has been attained. The key importance of crystalline Si nanostructures in determining the behaviour of porous Si is highlighted. The fabrication of solid-state electroluminescent devices is a prominent goal of many studies and the impressive progress in this area is described.
2,371 citations