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1
Karlsson, Linda. "Biomolecular interactions with porous silicon /." Linköping : Univ, 2003. http://www.bibl.liu.se/liupubl/disp/disp2003/tek804s.pdf.
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Wielgosz, R. I. "Electrochemical studies of porous silicon." Thesis, University of Bath, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296302.
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Boswell, Emily. "Field emission from porous silicon." Thesis, University of Oxford, 1997. http://ora.ox.ac.uk/objects/uuid:a4344196-7fc2-4713-b47b-85920b137759.
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Vacuum microelectronic (VME) devices are of interest for the development of flat-screen displays and microwave devices. In many cases, their operation depends on the field emission of electrons from micron-sized cathodes (semiconductor or metal), into a vacuum. Major challenges to be met before these devices can be fully exploited include obtaining - low operating voltages, high maximum emission currents, uniform emission characteristics, and long-term emission stability. The research in this thesis concerns the production of silicon field emitters and the improvement of their emission properties by the process of anodisation. Anodisation was carried out for short times, in order to form a very thin layer of porous silicon (PS) at the surface of both p and p+-type silicon emitters. The aim in doing this was to form a high density of asperities over the surface of the emitters. It was the intention that these asperities, rather than the "macroscopic" apex of the emitter, would control emission. This was the first work of its kind to be carried out. Transmission electron microscopy was used to characterise the morphology of p and p+-type silicon emitters before and after anodisation. Both the structure and arrangement of the surface fibrils, the thickness of the PS layers at the apex and nature of PS cross-sections were studied. The morphology was correlated to subsequent field emission measurements. Field emission characteristics, before and after anodisation, were obtained using a scanning electron microscope adapted for field emission measurements, and a field emission microscope. Extensive measurements showed that, following anodisation, there was substantial improvement in emission behaviour. After anodisation, the following was found to be true: i) The starting voltage was reduced by up to 50% (with p+
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Koker, Lynne. "Photoelectrochemical formation of porous silicon." Thesis, University of Birmingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368290.
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Zheng, Wan Hua. "Photoluminescence study of porous silicon." HKBU Institutional Repository, 1998. http://repository.hkbu.edu.hk/etd_ra/138.
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Ngan, Mei Lun. "Photoluminescence excitation of porous silicon." HKBU Institutional Repository, 1998. http://repository.hkbu.edu.hk/etd_ra/139.
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DEMONTIS, VALERIA. "Porous Silicon applications in biotechnology." Doctoral thesis, Università degli Studi di Cagliari, 2007. http://hdl.handle.net/11584/266040.
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Biotechnology is a field in great expansion and the continuous boost for obtaining smaller and more efficient devices stimulates the increase of interest from the research community. Nanostructured materials, and among them porous silicon (PS), appear to be good candidates for coupling with biological molecules because of their peculiar characteristics. In the case of porous silicon, the most noticeable are the very large specific area, which allows the loading of large amounts of biological material in a very small volume, and the possibility to easily tailor the pore size and morphology as function of the kind of molecules to be introduced.
Besides, the proven biocompatibility and non toxicity of PS allow the development of electronic devices to be directly implanted into living organisms without risk of rejection.
In this thesis we mainly focus our attention on the fabrication and characterization of a porous silicon-based potentiometric biosensor for triglycerides analysis, made of a lipase immobilized on a mesoporous Si matrix. Prototypes, realized on 1 x 1 cm n+-type silicon wafers, show a very high enzymatic activity. Moreover the properties of these biosensors have been shown to be stable in a several months time interval, clearly showing their advantages with respect to traditional triglycerides detection systems. The Michaelis Menten curve is obtained to demonstrate the absence of diffusion problems. Potentiometric measurements are also shown.
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Mabrook, Mohammed Fadhil. "Fabrication and characterisation of porous silicon." Thesis, Sheffield Hallam University, 2000. http://shura.shu.ac.uk/19990/.
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A systematic study has been made of the electrical conduction processes through electrically etched porous silicon (PS) films sandwiched between two metal electrodes. The PS layers were formed by anodisation of p-type silicon wafers in a hydrofluoric (HF) acid solution. The effect of fabrication conditions on the structural and electrical properties of PS have been investigated. The thickness of PS layers was found to depend on the anodisation time, whereas porosity was regarded to be controlled by the current density and HF acid concentration. The dark current-voltage I(V) characteristics at fixed temperature and the variation of current as a function of temperature have been established. The characteristics for all devices, regardless the metal contact, show a rectifying behaviour with ideality factor close to unity. It was found that PS films fabricated from p-type silicon substrates behave like n-type silicon due to the depletion of electronic holes. The results suggest that a pn heterojunction between PS and p-Si is responsible for the rectifying behaviour. A value of 0.7 eV was obtained for the barrier height at the interface between PS and p-Si at room temperature. The barrier height was found to increase with rising temperature. Recombination conduction process was found to be dominant at low temperatures as the activation energy did not exceed 0.22 eV. At high temperatures, thermionic emission diffusion process was found to be responsible for the current transport in the PS structures. A band model was proposed for metal/PS/p-Si/metal structures in order to explain the observed characteristics. A.c. dark current measurements revealed that the a.c. conductivity varies as ws where w is the angular frequency and s' is an index which depends on temperature and having a value less than unity. A.c. activation energy was interpreted in terms of hopping conduction at low temperatures (less than 200 K) and diffusion transport of charge carriers through PS layers at higher temperatures. Measurements of capacitance as a function of frequency and temperature showed a decrease with increasing frequency and increase with increasing temperature. The photoconduction behaviour of PS was characterised by high dark resistivity, a clear photosensitivity for visible light, and a bias voltage dependence of the spectral response.
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Squire, E. K. "Light emitting microstructures in porous silicon." Thesis, University of Bath, 1999. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285287.
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Gao, Wei. "Oxidation of nitride-bonded silicon carbide (NBSC) and hot rod silicon carbide with coatings." Thesis, University of Strathclyde, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366751.
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DeBoer, John Raymond. "Evaluation Methods for Porous Silicon Gas Sensors." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4971.
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This study investigated the behavior of porous silicon gas sensors under exposure to CO, NO, and NH3 gas at the part per million level. Parameters of interest in this study included the electrical, environmental, and chemi-resistive performance associated with various porous silicon morphologies. Based upon the variability of preliminary results, a gas pulsing method was combined with signal processing in order to analyze small impedance changes in an environment of substantial noise. With this technique, sensors could be effectively screened and characterized. Finally this method was combined with various post-treatments in order to improve the sensitivity and selectivity of individual sensors.
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Pap, A. E. (Andrea Edit). "Investigation of pristine and oxidized porous silicon." Doctoral thesis, University of Oulu, 2005. http://urn.fi/urn:isbn:9514277759.
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While numerous publications deal with the properties and applications of porous silicon (PS), some of the related topics are not complete or could be investigated from different aspects. Therefore, the main objective of this thesis is to provide novel information associated with the optical and chemical properties of PS.
For the investigations, various PS samples are manufactured by electrochemical dark etching of boron-doped p+-type Si wafers. Amongst others, (i) the wavelength-dependent refractive indices of freestanding PS monolayers having different porosities were obtained from optical transmission and reflection spectra in the 700–1700 nm wavelength range, and compared to those calculated from Bruggeman's effective medium approximation (EMA). The refractive indices of the PS samples are shown to be described well with the EMA. In addition, optical scattering at the air-PS interface was demonstrated. (ii) Multilayer stacks are created by alternating the porosities of PS layers within the same sample to form Bragg filters. The Bragg conditions of the filters are calculated and compared to optical transmission measurements. (iii) The oxidation of PS membranes in dry air is investigated with emphases on the reaction kinetics and on the structural changes of the porous matter. As revealed, oxidation proceeds faster in PS than in Si bulk. The formed SiO2 is amorphous and causes stress in the lattice of the residual Si skeleton. (iv) The effect of oxidation extent of PS layers on the growth mechanism of multi-walled carbon nanotubes (CNTs) is investigated. The density of the CNT network is found proportional to the oxidation extent of the substrates. (v) Finally, the chemically-reductive nature of PS is studied and exploited via the immersion plating method to deposit palladium and silver nanoparticles in the nanopores and on the surface of PS samples.
The presented novel results have potential in silicon-based technologies, including integrated active and passive optical components (waveguides, filters, antireflection coatings, optical gas/liquid sensors), electronic devices (electrochemical gas/liquid sensors, diodes, field effect devices) and selective chemical catalysis (substrates, growth templates).
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余家訓 and Ka-fan Yu. "Scanning probe microscopy of porous silicon formation." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31222110.
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Chang, Wai-Kit. "Porous silicon surface passivation and optical properties." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/41426.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1996."June 1996."
Includes bibliographical references (leaves 84-85).
by Wai-Kit Chang.
S.M.
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To, Wai Keung. "Tunable wavelength from porous silicon-based devices." HKBU Institutional Repository, 2009. http://repository.hkbu.edu.hk/etd_ra/1094.
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Tsuboi, Takashi. "Structure and Properties of Porous Silicon Surface." Kyoto University, 1999. http://hdl.handle.net/2433/181681.
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Tobail, Osama. "Porous silicon for thin solar cell fabrication." Aachen Shaker, 2008. http://d-nb.info/992052904/04.
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Al-Ajili, Adwan Nayef Hameed. "Photoluminescence of nanostructured silicon." Thesis, Loughborough University, 1996. https://dspace.lboro.ac.uk/2134/26999.
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The photoluminescence (PL) emitted by porous silicon has been investigated under different conditions of excitation using a pulsed nitrogen laser source, and the continuous tunable DV synchrotron source at Daresbury Laboratory. The project involved sample preparation, and PL measurements using a custom-built optical laser-based system for lifetime measurements. This in itself necessitated software and hardware development to enable interfacing and data-logging using an IBM-compatible PC. The equipment development formed a major part of the project.
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Khung, Yit Lung, and y. khung@unsw edu au. "Porous Silicon Structures for Biomaterial and Photonic Applications." Flinders University. School of Chemistry, Physics and Earth Sciences, 2009. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20090421.145533.
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The primary research aim in this thesis is to demonstrate the versatility of porous silicon based
nanomaterials for biomaterial and photonic applications. In chapter 2 of this thesis, the
suitability of porous silicon as a biomaterial was investigated by performing different surface
modifications on the porous silicon films and evaluating biocompatibility of these surfaces in
vitro. The porous silicon surfaces were characteriszed by means of atomic force microscopy
(AFM), scanning electron microscopy (SEM), diffuse reflectance infrared spectroscopy (DRIFT)
and interferometric reflectance spectroscopy (IRS). Cell attachment and growth was studied
using fluorescence microscopy and cell viability assays. Both fabrication of the porous silicon
films and subsequent surface modifications were demonstrated. Polyethylene glycol
functionalised porous silicon prevented cell attachment, whilst collagen or fetal bovine serum
coating encouraged cell attachment. Surface modifications were also performed on porous
silicon films with different pore sizes and the influence of pore size and surface modification on
primary hepatocyte growth was recorded over a course of 2 weeks by means of laser scanning
confocal microscopy (LSCM), toxicity and metabolic assays. On collagen-coated surfaces with
average pore sizes of 30 nm, multilayer cells stacks were formed. This stacking behaviour was
not observed on samples with smaller pore sizes (10 nm), or in the absence of collagen.
Hepatocytes remained viable and functional (judging by a metabolic assay) for 6 days, after
which they generally underwent apoptosis. Collagen-coated porous silicon films showed later
onset of apoptosis than porous silicon films not coated with collagen or collagen-coated flat
silicon..
In chapter 3 of this thesis, the nitrogen laser of a laser desorption/ionization (LDI) mass
spectrometer was used to selectively ablate regions on porous silicon films that had been
functionalised with a non-fouling polyethylene oxide layer, affording a microscale patterning of
the surface. Surface characterization was performed by means of AFM, SEM, LDI mass
spectrometry, DRIFT and IRS. This approach allowed the confinement of mammalian cell
attachment exclusively on the laser-ablated regions. By using the more intense and focussed
laser of a microdissection microscope, trenches in a porous silicon film were produced of up to
50 micron depth, which allowed the construction of cell multilayers within these trenches,
mimicking the organization of liver cords in vivo. Fluorescent staining and LSCM was used to
study cell multilayer organization.
To gain a better understanding of how surface topography influences cell attachment and
behaviour, porous silicon films were fabricated containing a gradient of pore sizes by means of
asymmetric anodisation (chapter 4). These gradients allowed the investigation of the effect of
subtle changes of pore size on cell behaviour on a single sample. Analysis by means of LSCM
and SEM showed that pore size can dictate cell size and area as well as cell density. In addition,
a region of pore size where cell attachment and proliferation was strongly discouraged was also
identified. This information can prove to be useful for designing non-biofouling surface
topographies.
Using the same asymmetric anodisation setup, photonic mirrors gradients were produced and
overlaid over one another to produce multidirectional lateral photonic mirror gradients that
display a series of roving spectral features (photonic stop-bands) from each gradient layer
(chapter 4). These multidirectional photonic gradients have the potential to serve as optical
barcodes or contributing to the development of graded refractive index devices such as lenses for
high quality image relay and graded-index optical fibers.
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Thảo. "Photoluminescence spectroscopy on erbium-doped and porous silicon." Amsterdam : Amsterdam : [s.n.] ; Universiteit van Amsterdam [Host], 2000. http://dare.uva.nl/document/83659.
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Henstock, James Rolleston. "Porous silicon-polycaprolactone composites for orthopaedic tissue engineering." Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/11022/.
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Silicon is an essential element in human nutrition, with the symptoms of a silicon-deficient diet being abnormal bone development (Carlisle, 1972). Similarly, animals and bone forming osteoblast-like cells in vitro show an increase in bone growth when supplemented with the soluble, bioavailable form of silicon, orthosilicic acid [Si(OH4)] (Carlisle, 1988). Certain bioactive glass compositions can form a strong chemical bond with bone, doing so by dissolving to form a solution that includes orthosilicic acid which re-polymerises to form a hydrated silica gel layer that adsorbs growth factors, supports cell growth and acts a nucleation bed for bone mineral (Hench, 1980). Bioactive glass degradation products alone have also been shown to significantly enhance the activity of osteoblasts in vitro (Xynos et al, 2001). Pure, crystalline silicon is not soluble in water or body fluids, but when electrochemically etched with hydrofluoric acid, nanoscale silicon hydride-lined pores are formed through the material which render it soluble in aqueous solutions, yielding orthosilicic acid (Canham, 1996). Porous silicon has therefore been proposed as a novel orthopaedic biomaterial, acting in a similar way to bioactive glasses. In addition, the long, narrow pores can be filled with pharmaceuticals, creating a dissolvable drug delivery material with release kinetics that are easily controllable by adjusting the pore morphology and drug loading density (Anglin et al, 2008). This research aims to evaluate porous silicon (pSi) as a therapeutic biomaterial for bone tissue engineering applications in the form of a composite with the biodegradable polymer, polycaprolactone (PCL). pSi microparticles were incorporated into a polycaprolactone matrix and the composites characterised in terms of the ability to generate orthosilicic acids under various conditions. It was found that the composites released silicic acids at a rate proportional to the loading proportion of pSi, with 8% composites (20mg pSi in 230mg PCL) eluting ~400 ng.ml-1 Si per day. At this composition, pSi increased the amount of calcium phosphate formed on the composite in a simulated body fluid and this had the morphology and molar ratio of biological apatite (Ca:P ≈ 1.5). The addition of 8% pSi to polymers enhanced the electroconductivity of hydrogels by two orders of magnitude and did not significantly affect mechanical strength. The release profiles of small molecules such as gentamicin and large hydrophobic proteins such as alkaline phosphatase were enhanced by pre-loading sample drugs into pSi rather than directly loading drugs into PCL. Crucially, the molecules retained their activity following release. Other proteins such as bovine serum albumin were adsorbed onto the surface silica gel layer, suggesting a method for localising growth factors onto biomaterial surfaces. Osteoblasts responded well to 8% pSi-PCL composites, producing significantly more collagen and glycosaminoglycans in vitro. Collagen in the extracellular matrix (ECM) was also significantly more highly crosslinked as determined by the pyridinium content of ECM lysates and was more mineralised than the ECM on PCL alone. The breakdown products of pSi also significantly enhanced the osteoblastic phenotype of cells in vitro. This research demonstrates that porous silicon can be added to polymer-based materials to enhance their effectiveness as biomaterials for orthopaedic tissue engineering.
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Arrand, Helena Frances. "Optical waveguides and components based on porous silicon." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243510.
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Polisski, Sergej. "Porous silicon/noble metal nanocomposites for catalytic applications." Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.545317.
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Today, bulk silicon is one of the best studied semiconductors. However, in its different nano-modifications, e.g. as porous silicon, totally new properties are exhibited. Despite the fact, that porous silicon is widely known and has been extensively studied since the 1990s, many unique features of this material are still unexplored. In this work, specific functionalities of porous silicon prepared, utilising both solid (via electrochemical or stain etching processes) and gas phase (from silane) syntheses, were investigated. Since this study was in-part industry oriented, the emphasis has been placed upon the investigation of porous silicon nanostructures, made from low cost metallurgical grade polycrystalline silicon powder. It has been previously demonstrated that porous silicon exhibits a very large, hydrogenated internal surface area (up to 500 m2 g−1). It is verified in this work, that morphological properties of this material result in a high reductive potential of its internal surface due to hydrogen passivation. Therefore, in this thesis, we would like to show that porous silicon-based reactive templates are promising for their applications in nanometal-supported catalysis. We used salts of platinum, gold, palladium, silver and their mixtures, which were reduced on the silicon nanocrystalline internal surface, resulting in formation of metal nanoparticles embedded into porous silicon matrix. Various experimental techniques were used to evaluate the morphology, size and composition of metal nanoparticles, as well as their growth rates. Hydrogen effusion experiments proved the crucial difference between porous silicon and other chemically inert supporting templates for the process of metal nanoparticles formation. The catalytic activity of the synthesised materials was evaluated in gas phase conversion of CO to CO2. Furthermore, the new porous silicon-based catalysts were tested in gas/liquid phase reactions as well, using hydrogenation, oxidation, dehalogenation and C-C coupling class reactions. Following the trends of “state of the art” current Si technology, we present the design of the developed flow microreactor, based on patterned Si wafer, which can be implemented in future work to catalyse selected reactions. Results obtained in this work suggest that porous silicon matrices are promising supports for metal nanoparticle based catalysis.
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Gunasingam, Pathma V. "Adsorption and desorption of gases in porous silicon." Thesis, Middlesex University, 2001. http://eprints.mdx.ac.uk/13588/.
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This research was undertaken to provide an understanding of the nature, origin and desorption mechanism of species found on the porous silicon (PS) surface and the changes that occur when PS is stored under varying conditions. The PS used in this work was produced from p-, high-resistivity FZ c-Si substrates. Three types of commonly used HF-based electrolytes were chosen for anodisation, under the same process conditions. With the resulting samples, temperature programmed desorption (TPD) coupled with mass spectrometry were used to identify species liberated at different temperatures. FTIR was also used to investigate the nature of surface species on PS and hence to infer how these give rise to the observed volatile products. After various modifications, the TPD system with the custom-made heating unit and the appropriate methodology were developed to suit the present work. Freshly anodised PS in the vacuum chamber at room temperatures gave somewhat enhanced peaks due to air components (0 ⁺, N₂⁺ and/or CO⁺, O₂⁺ and CO₂⁺) and, most significantly, an increase in F-containing species (e.g. F ⁺), derived from the electrolyte. On heating, the main desorbed species were found be hydrogen, silane, Si-Fx species, and Hx-Fx species. TPD spectra for hydrogen showed two peak maxima with a "hump". This implies two types of hydrogen environments; these were assigned as Si-H (lower temperature peak) and Si-H₂ (higher temperature peak) species on the PS surface. The temperature difference between the two peaks was similar (~100K) in all three cases. This shows that hydrogen desorption occurs similarly from PS prepared using the three different electrolytes. It also suggests that hydrogen adsorption during PS formation occurs analogously in the three electrolytes. Silane was observed to desorb at 575K. It is proposed that this comes from -SiH3 groups on the PS surface, possibly after reaction with sorbed water. A mechanism is suggested. In contrast, desorption of Si-Fx species was found to be sensitive to the nature of the electrolyte. The lower temperature peaks from the TPD experiments are assigned to H₂SiF₆ , SiF ₄ and perhaps H₂SiF₂ (by-products from anodisation) sorbed on PS. They are held relatively weakly by electrostatic and/or van der Waals forces. The higher temperature peak assigned to SiF₃ + may be explained in terms of migration of F atoms followed by Si-SiF₃ bond breakage. The various Hx-Fy products derive from species present in the HF electrolytes. To investigate changes in PS under typical storage conditions, samples were kept in (i) a blue wafer box, (ii) a screw-top white box and (iii) a similar box in a vacuum desiccator. The PS was then analysed by FTIR after various time intervals. After one month, only PS stored under condition (iii) was unchanged. The other samples showed evidence of oxidation, attributed to hydrolysis, fonnation of silanol (SiO-H) species, and back-bond oxidation of Si-Hx groups. Further ageing revealed inclusion of C-H species on PS. This work is a contribution to understanding of PS behaviour, and is relevant to its applications in electronic devices and sensors.
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Chau, Chien Fat. "A nanostructured porous silicon based drug delivery device." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/69237/.
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Targeted and controlled delivery of therapeutic agents on demand is pivotal in realising the efficacy of many pharmaceuticals. The design and fabrication of a novel, electrically-addressable, porous structure-based drug delivery device for the controlled release of therapeutic proteins and peptides, are described in this thesis. The initial prototype microdevice design incorporates a porous polysilicon (PPSi) structure as a drug reservoir. Two alternative methods were investigated to fabricate the PPSi structure: i) the chemical stain etching method; ii) a reactive ion etching (RIE) method through a masking template. Random pores, with irregular pore shape and size in the micro- to mesoporous regime (< 50 nm), were obtained using the stain etching method but this method suffered from poor reproducibility and non-uniformity. Two novel RIE approaches were investigated to fabricate ordered PPSi structures; two different masking templates were investigated – a porous anodic alumina (PAA) and a metal mask with hexagonally arranged holes produced by a novel nanosphere lithography (NSL) technique. A quasi-ordered PAA template with pore diameters in the region of 50 nm was fabricated but was not suitable for the subsequent proposed RIE process. By using the NSL technique, quasi-ordered PPSi structures with tapered pore profiles, were obtained. This is the first demonstration of the fabrication of PPSi with ordered pores of sizes in the macropore range of ~ 370 nm. A revised silicon-based prototype microdevice was designed and fabricated. The microdevice incorporates a nanostructured, quasi-ordered porous silicon (PSi) as a drug reservoir and an integrated heater and temperature sensor as an active control mechanism. The PSi structure was fabricated using a modified NSL technique and a Bosch-based RIE process. Hexagonally arranged cylindrical pores with diameters between ~75 nm and ~120 nm, and depths in the range of ~330 nm and 500 nm, were obtained. The novel fabrication techniques investigated here are simple and versatile; both p-type and n-type PSi structures have been successfully fabricated. Proof-of-concept studies, using the revised prototype drug delivery microdevices, suggested that the nanostructured PSi would be suitable for the passive release of an intermediate-sized (~23 000 Dalton) model protein. It is envisaged that the microdevice has the potential to deliver osteoinductive growthfactors, on demand, to the site of fracture, in a controlled and sustainable manner, as a first step to an intelligent therapeutic system for skeletal regeneration.
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Dancil, Keiki-Pua S. "Development of an optically based porous silicon biosensor /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1999. http://wwwlib.umi.com/cr/ucsd/fullcit?p9936839.
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Gao, Ting. "Vapor sensors using porous silicon-based optical interferometers /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2002. http://wwwlib.umi.com/cr/ucsd/fullcit?p3061646.
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He, Yingning. "Lateral porous silicon membranes for planar microfluidic applications." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30255/document.
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Les laboratoires sur puce visent à miniaturiser et à intégrer les fonctions couramment utilisées dans les laboratoires d'analyse afin de cibler des applications en santé avec un impact prometteur sur le diagnostic médical au lit du patient. Les membranes poreuses sont d'un grand intérêt pour la préparation et l'analyse d'échantillon sur puce car elles permettent la séparation par taille/charge de molécules, mais également leur pré-concentration. Parmi les matériaux disponibles pour constituer des membranes poreuses, le silicium poreux présente de nombreux avantages tels que le contrôle précis de la taille des pores et de la porosité, une chimie de surface pratique et des propriétés optiques uniques. Les membranes de silicium poreux sont généralement intégrées dans des puces fluidiques en les montant entre deux couches comportant des micro-canaux, formant ainsi des réseaux fluidiques à trois dimensions, peu pratiques et peu adaptés à l'observation directe par microscopie. Dans ces travaux de thèse, nous avons développé deux méthodes de fabrication de membranes de silicium à pores latéraux qui permettent leur intégration monolithique dans des systèmes microfluidiques planaires. Le premier procédé est fondé sur l'utilisation d'électrodes localement structurées afin de guider la formation de pores de manière horizontale, en combinaison avec des substrats type silicium sur isolant (SOI) pour localiser spatialement la formation de silicium poreux dans la profondeur du canal. La deuxième méthode repose sur le fait que la formation de silicium poreux par anodisation est fortement dépendante du type de dopant et de sa concentration. Bien que nous utilisons encore le même type d'électrodes structurées sur les parois latérales de la membrane pour injecter le courant lors de l'anodisation, le dopage par implantation permet de confiner la membrane, de façon analogue mais à la place de l'oxyde enterré du SOI. Des membranes à pores latéraux ont été fabriquées par ces deux méthodes et leur fonctionnalité a été démontrée en réalisant des expériences de filtrage. En plus de la filtration d'échantillon, les membranes ont été utilisées pour étudier la possibilité d'effectuer de la pré-concentration électrocinétique et de la détection interférométrique. La sélectivité ionique des membranes microporeuse permet la pré-concentration moléculaire avec des facteurs de concentration pouvant atteindre jusqu'à 103 en 10 min en appliquant moins de 9 V. Ces résultats sont comparables à ceux rapportés dans la littérature à l'aide par exemple de nanocanaux avec une consommation d'énergie beaucoup plus faible. Enfin, nous avons pu détecter une variation de l'indice de réfraction du silicium poreux par le décalage du spectre d'interférence lors du chargement de différents liquides injectés dans les membranes. Le travail présenté dans cette thèse constitue la première étape dans la démonstration de l'intérêt du silicium poreux pour la préparation d'échantillon et la biodétection dans des laboratoires sur puce planairesLab on a chip devices aim at integrating functions routinely used in medical laboratories into miniaturized chips to target health care applications with a promising impact foreseen in point-of-care testing. Porous membranes are of great interest for on-chip sample preparation and analysis since they enable size- and charge-based molecule separation, but also molecule pre-concentration by ion concentration polarization. Out of the various materials available to constitute porous membranes, porous silicon offers many advantages, such as tunable pore properties, large porosity, convenient surface chemistry and unique optical properties. Porous silicon membranes are usually integrated into fluidic chips by sandwiching fabricated membranes between two layers bearing inlet and outlet microchannels, resulting in three-dimensional fluidic networks that lack the simplicity of operation and direct observation accessibility of planar microfluidic devices. To tackle this constraint, we have developed two methods for the fabrication of lateral porous silicon membranes and their monolithic integration into planar microfluidics. The first method is based on the use of locally patterned electrodes to guide pore formation horizontally within the membrane in combination with silicon-on-insulator (SOI) substrates to spatially localize the porous silicon within the channel depth. The second method relies on the fact that the formation of porous silicon by anodization is highly dependent on the dopant type and concentration. While we still use electrodes patterned on the membrane sidewalls to inject current for anodization, the doping via implantation enables to confine the membrane analogously to but instead of the SOI buried oxide box. Membranes with lateral pores were successfully fabricated by these two methods and their functionality was demonstrated by conducting filtering experiments. In addition to sample filtration, we have achieved electrokinetic pre-concentration and interferometric sensing using the fabricated membranes. The ion selectivity of the microporous membrane enables to carry out sample pre-concentration by ion concentration polarization with concentration factors that can reach more than 103 in 10 min by applying less than 9 V across the membrane[TL1]. These results are comparable to what has already been reported in the literature using e.g. nanochannels with much lower power consumption. Finally, we were able to detect a change of the porous silicon refractive index through the shift of interference spectrum upon loading different liquids into the membrane. The work presented in this dissertation constitutes the first step in demonstrating the interest of porous silicon for all-in-one sample preparation and biosensing into planar lab on a chip
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PINNA, ELISA. "Impregnation of porous silicon matrices for technological applications." Doctoral thesis, Università degli Studi di Cagliari, 2020. http://hdl.handle.net/11584/284139.
Full textAbstract:
Porous silicon (PSi) is a very versatile material, whose main feature is the large developed surface. This inner surface, generated by the presence of pores, makes PSi particularly suitable for applications needing pores impreg- nation. In this way, many new different systems can be formed, and their characteristics can be exploited for several technological applications. PSi, beneath its complex nature, is very attractive in many different technological fields, from energy storage and production, sensors and optoelectronic devices and biomedical applications. Many research efforts have been done for the optimization of these kind of devices, including the optimization of pores impregnation mechanisms, aiming at the improvement of the performances of the final structures.
In this PhD thesis I will report a study on the impregnation of PSi with different materials for a variety of technological applications. In particular, the impregnation process has been studied for organic and inorganic materials, with the aim of optimizing the process and, as a consequence, the samples properties.
In the first part of this study, the chemical impregnation of the PSi matrix with melanin will be presented. After a brief introduction on the past discoveries on the hybrid junction, I will present the results in the understanding of the mechanisms governing the penetration of melanin starting monomers and their polymerization into melanin, together with the improvement we achieved in increasing the lifetime of the hybrid structure in terms of production of photogenerated current. I will also present the results obtained using a different PSi matrix, that is a porous structure obtained by using metal- assisted chemical etching (MACE). The MACE approach has been used to limit the high Si reflectivity by a suitable surface structurations. The impregnation of MACE-formed structures with melanin is then aimed at an increase of the photovoltaic properties lead by the increased light power entering the MACE-based structures.
v
The second part of the project regards the PSi impregnation with inorganic materials using an electrochemical approach for the impregnation of the porous matrix with erbium and nickel. Erbium has been chosen because of its demonstrated photoluminescence (PL) properties when hosted in a silicon matrix; the interest on this topic has started to decrease when it has been found that erbium clustering limits the PL emission. In this thesis I will show by a wide multidisciplinar study that pores filling, instead of the standard pores doping approach, can be a promising route to overcome the erbium clusters formation and to enhance the PL intensity. The impregnation of PSi with nickel has a different goal and is aimed at the fabrication of a multiphase material that can be used to define a valid protocol for the analysis and accurate reconstruction of nanoporous materials with atom probe tomography (APT), a technique lacking of a reliable approach for the definition of accurate reconstruction parameters. The main characteristic of this particular pair of materials is that silicon and nickel have similar evaporation fields, which is essential to perform the analysis of porous composite materials with APT. Despite the different materials and the various technological applications of the analyzed samples, the common feature of the work is the study of the impregnation processes. A good understanding of the impregnation process is the base for the optimization of the final device. The understanding and control of the parameters governing the filling of meso- and nano-pores is in fact a very complex matter that is unavoidably influenced by many environmental parameters (temperature, humidity...) that can be difficult to control properly. For these reasons, my PhD work has been aimed at the understanding of what parameters are fundamental for a successful pores impregnation and why.
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Hee, Song Jae. "Quenching of porous silicon photoluminescence by aromatic molecules, and surface derivatization of porous silicon with dimethyl sulfoxide, aryllithium, or alkyllithium reagents /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1998. http://wwwlib.umi.com/cr/ucsd/fullcit?p9835389.
Full text
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Alvarez, Sara D. "Stability and biocompatability of porous silicon and porous alumina for cell and biomolecular sensing." Diss., [La Jolla, Calif.] : University of California, San Diego, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3338847.
Full textAbstract:
Thesis (Ph. D.)--University of California, San Diego, 2008.Title from first page of PDF file (viewed Jan. 13, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 126-141).
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Riley, David Washington. "Porous silicon thin films : a study of their optical properties and growth mechanism." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/19627.
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Andrews, Gordon Todd. "Elastic and structural properties of supported porous silicon layers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0004/NQ42470.pdf.
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Lewis, Stephen Edward. "The Creation of a Viable Porous Silicon Gas Sensor." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14614.
Full textAbstract:
This dissertation describes the fabrication and operation of porous silicon gas sensors. The first chapter describes the motivation behind gas sensor research and provides the reader with background knowledge of gas sensors including the terminology and a review of various gas sensors. The following two chapters describe both how the porous silicon gas sensors are created and how they have been tested in the laboratory. Chapter 4 describes the steps required to create arrays of gas sensors to provide for a selective device through the application of patented selective coatings. Chapter 5 proposes a physical model that leads to a numerical solution for predicting the operation of the gas sensor. The next chapter builds from this model to analyze and optimize the experimental methods that are used to test both this and other gas sensors. The final chapter of this dissertation describes the prototype gas sensor system that has most recently been created, the company that was formed to further the development of that system, and the future applications of the porous silicon gas sensor.
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Luongo, Kevin. "Palladium Doped Nano Porous Silicon to Enhance Hydrogen Sensing." Scholar Commons, 2006. http://scholarcommons.usf.edu/etd/3896.
Full textAbstract:
A mass manufacturable impedance based, palladium doped porous silicon sensor, was fabricated for hydrogen detection. The sensor was built using electrochemical etching to produce mesoporous silicon. Four nanometers of palladium was defused directly into the porous silicon and another four nanometers of Pd was deposited on the defused surface to enhance sensing. The sensor was tested in a sealed chamber in which the impedance was measured while hydrogen in nitrogen was ranged from 0-2 percent. Unlike conventional hydrogen sensors this sensor responded at room temperature to changes in hydrogen concentration. The electrical impedance response due to adsorption and desorption of hydrogen reacted relatively quickly due to the nanoparticle nature of palladium diffusion in and Pd evaporation on porous silicon.
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Tobail, Osama [Verfasser]. "Porous Silicon for Thin Solar Cell Fabrication / Osama Tobail." Aachen : Shaker, 2009. http://d-nb.info/1161311378/34.
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Thomas, Leigh-Anne. "Porous silicon multilayers for gigahertz bulk acoustic wave devices." Thesis, University of Bath, 2011. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.545312.
Full textAbstract:
Acoustic filters for signal filtering are used in wireless technologies operating at gigahertz frequencies for communication systems such as next generation cell phones. Multilayered porous silicon structures have been fabricated from silicon wafers to create the Bragg mirror section of a bulk acoustic wave filter. These porous silicon multilayers have been designed for use from 500 MHz – 20 GHz with primary focus on frequencies at 1 GHz. The porous silicon multilayers consist of alternating layers of high and low acoustic impedance layers on a bulk silicon substrate. They are fabricated using electrochemical etching where the current density during the etch determines the porosity and hence acoustic impedance of each layer. Bragg mirrors, FabryPerot filters, microcavities and rugate filters can be produced in this way due to the control of the tuneable porosity profile throughout the structure. The porosity of the layer modifies the elastic constants of the layer such as the Young’s modulus and hence the velocity of the bulk acoustic waves travelling through it. The behaviour of bulk acoustic waves through silicon is known but in order to fabricate porous silicon acoustic filters, the dependence of the longitudinal wave velocity as a function of porosity must also be known. This has been studied using acoustic transmission measurements on single porous silicon layers and then extended to multilayered structures. Rugate filters are single frequency filters that have not previously been studied for acoustic applications. In this study the first acoustic rugate filters have been fabricated using porous silicon material that exhibit only one stopband near 1 GHz. Bragg mirrors have been made with acoustic transmission measurements showing the locations of the stopbands. Porous silicon microcavities have also been fabricated along with filters that have apodisation functions. This work could form the basis of future efforts to produce and incorporate allSi multilayers into acoustic filters that are easily fabricated at a high level of quality and reliability that will serve to be efficient and cost effective.
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Orosco, Manuel. "Amplified detection of protease activity using porous silicon nanostructures." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3352688.
Full textAbstract:
Thesis (Ph. D.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed June 16, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 134-141).
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Wang, Yu Hsiung, and 王馭熊. "Porous Silicon Photodetector." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/75992435761016291202.
Full textAbstract:
碩士國立中山大學
電機工程研究所
84
A high sensitivity porous silicon (PS) photodetector is fabricated through rapid thermal oxidation (RTO) and ra- pid thermal annealing (RTA) processes. A RTO process is used to passivate the surface of PS and therefore to en- hance the photoresponsivity of the PS layer. A RTA proc- ess is employed to improve the quality of the oxide layer on the surface of PS layer and hence to reduce the dark current of the PS photodetector. Under our optimum prep- aration conditions, photocurrent can reach 21 mA(under 22.92mW tungsten lamp illumination) and dark current is about 5.4 uA(at the reverse bias of 10V). The quantum e- fficiencies of above 90% at the wavelength shorter than 750nm and of 80% to 70% in the range of wavelength from 750nm to 1050nm are obtained. It is demonstrated that a RTA-RTO-PS photodetector behaves as a blue- enhanced metal -i-p photodetector. Of utmost importance is the incidence of photoresponsivity at the wavelength longer than 1600nm. We attribute it to the absorption of photons with the help of band offset at the natural heterointerface between PS and Si.
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"Photoluminescent properties of porous silicon." Chinese University of Hong Kong, 1993. http://library.cuhk.edu.hk/record=b5887722.
Full textAbstract:
by Kan Chi Fai.Title also in Chinese characters.
Thesis (M.Phil.)--Chinese University of Hong Kong, 1993.
Includes bibliographical references (leaves 120-124).
Acknowledgements
Abstract
Chapter Chapter 1 --- Introduction --- p.1
Chapter Chapter 2 --- Proposed mechanisms of the visible photoluminescence of porous silicon --- p.5
Chapter Chapter 3 --- Sample Preparation --- p.15
Chapter 3.1 --- Anodization of porous silicon in an electrochemical cell --- p.15
Chapter 3.2 --- Appearances of samples --- p.18
Chapter 3.3 --- Uniformity of samples --- p.21
Chapter 3.4 --- Formation mechanism --- p.22
Chapter 3.5 --- Measurements of current-voltage characteristics --- p.23
Chapter 3.6 --- Current-Voltage (I-V) Characteristics --- p.24
Chapter 3.7 --- Voltage monitored at constant anodizing current --- p.37
Chapter 3.8 --- Mass lost due to anodization --- p.37
Chapter Chapter 4 --- Transmittance and reflectance studies --- p.42
Chapter 4.1 --- Transmittance and reflectance studies in the ultraviolet to near infrared range --- p.42
Chapter 4.1.1 --- Experimental setup of transmittance and reflectance spectroscopic studies --- p.42
Chapter 4.1.2 --- Transmittance spectra --- p.42
Chapter 4.1.3 --- Reflectance spectra --- p.48
Chapter 4.1.4 --- Optical thickness of the porous silicon layer --- p.60
Chapter 4.1.5 --- Effective medium approximation --- p.61
Chapter 4.1.6 --- "Determination of refractive index, porosity and thickness" --- p.66
Chapter 4.1.7 --- Thickness measured by optical microscopy --- p.67
Chapter 4.1.8 --- Validity of the effective medium approximation --- p.72
Chapter 4.2 --- Infrared transmission studies --- p.76
Chapter 4.2.1 --- Experimental setup --- p.76
Chapter 4.2.2 --- Infrared spectra --- p.75
Chapter Chapter 5 --- Photoluminescence and Photoexcitation --- p.82
Chapter 5.1 --- Photoluminescence studies --- p.82
Chapter 5.1.1 --- Experimental setup --- p.82
Chapter 5.1.2 --- Calibration of the spectral response of setup --- p.84
Chapter 5.1.3 --- The photoluminescence and the appearance of porous silicon --- p.88
Chapter 5.1.4 --- Effect of laser radiation on porous silicon --- p.95
Chapter 5.1.5 --- Photochemistry --- p.95
Chapter 5.1.6 --- Aging and photoluminescence --- p.97
Chapter 5.1.7 --- Annealing studies of porous silicon --- p.97
Chapter 5.1.8 --- Photoluminescence spectra --- p.100
Chapter 5.1.9 --- Interference --- p.106
Chapter 5.2 --- Photoexcitation studies --- p.107
Chapter 5.2.1 --- Experimental setup --- p.107
Chapter 5.2.2 --- Result --- p.108
Chapter Chapter 6 --- Discussions and conclusions --- p.112
Chapter 6.1 --- Information from peer groups --- p.112
Chapter 6.1.1 --- Raman scattering --- p.112
Chapter 6.1.2 --- X-ray diffraction --- p.112
Chapter 6.2 --- Photoluminescence and annealing --- p.113
Chapter 6.3 --- Photoluminescence and the etching conditions --- p.114
Chapter 6.4 --- Consideration of different models in the visible photoluminescence of porous silicon --- p.117
Chapter 6.5 --- Conclusions --- p.118
References --- p.120
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Lee, Cheng Hong, and 李政宏. "SOI Fabrication by Porous Silicon." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/95752136706226984790.
Full textAbstract:
碩士國立清華大學
電機工程研究所
84
SOI 擁有著許多的優點, 具有相當的潛力為下一代 ULSI 元件之基板 , 特別是當其成本能進一步調降時, 本計畫的目的即是欲透過一個新的構想 來製造出價格便宜的SOI基板。 這個構想一開始先在矽晶片上長出多孔 矽 (Porous Silicon), 接著以電化學陽極氧化的方式, 藉著多孔矽本身 的特性在其底部形成氧化層而留下表面一層單晶的矽。 利用此表層單晶 多孔矽為基材來磊晶, 當透過適當的磊晶成長及退火處理, 得到品質較 好的整片單晶 (Full Wafer), 而其底部已有一層平整的氧化層, 即得 到 SOI 結構。 或者將已具有底部氧化層之多孔矽晶片置於高溫爐中加 熱, 使其結構重整而緻密, 亦可得到 SOI 基板。此實驗首先必須長出一 層品質好的多孔矽, 例如可任意的控制多孔矽的厚度, 平整度以及孔隙 度 (Porosity)。接著就是要控制好氧化層的成長 , 必須要能將氧化層 集中成長於多孔隙的底部, 留下表面一層平整單晶結構的多孔矽; 此時 底部氧化層的厚度, 均勻度, 品質, 以及表層的多孔矽厚度及品質是實驗 時考慮的重點。 本計畫已成功地控制上述各重點之條件與方法。另一方 面, 我們知道多孔矽在發光上有所應用, 因此我們希望能清楚地了解電激 發光 (Electro-Luminescent) 的原理, 以進一步增加電激光效率。 同樣 如, 應用上述在多孔矽的底部形成一層氧化層的技術於電性量測上, 可 有效地減低流過矽基版的漏電流, 使得電流只流經多孔矽本身, 如此可減 輕矽基材的干擾, 而得到多孔矽的電氣特性。 這是本計劃之衍生優點, 值得更深入探討。
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Huang, ching-shing, and 黃景興. "Positron lifetime in porous silicon." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/08282590860042380405.
Full textAbstract:
碩士國立臺灣大學
物理研究所
84
The lifetime of electron and positron annihilation is close- ly related to the structure of material including density of electron, size of voids and defects. through HF etching on the silicon wafers, it produces the micro channels and voids ,this is so called "porous silicon", Using the sensitive character of voids to positrons, we can study porous silicon . In our experiment,we use two kinds of porous silicon. One is etched with different acid, another is oxidized in the air with different time. Measuring the positron lifetime in the porous silicon, we hope to enhance the understanding of the porous silicon structure.
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So, Kam-Shing, and 蘇錦成. "The Formation of Porous Silicon." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/58096561786252415627.
Full textAbstract:
碩士國立交通大學
電子研究所
81
In this thesis, the growth and the characteristics of porous silicon are studied for the development of humidity sensors. The aim is to gain a better understanding on the physical characteristics and the formation process of porous silicon. An RH sensor has been fabricated with an interdigital aluminum contact on the selectively electrochemical anodization porous silicon area. The increase of current response measured in a multi-function & programmable temperature/humidity chamber is about 3 orders high in magnitude while the humidity changes from 15 to 90 %. The formation rate and the porosity of porous silicon have been investigated. It is found that the HF concentration plays a main role in determining the porosity of silicon, also the formation rate is affected by the current density and the HF concentration.
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PENG, GUO-RUI, and 彭國瑞. "Porous silicon and its applications." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/29738102805112494156.
Full textAbstract:
碩士國立中山大學
電機工程研究所
81
1990年，Canham以氫離子雷射檢試多孔矽，發現多孔矽具有效率高發光特性，且其光 淚發光譜在可見光的波長範圍，這項發現，無疑地將矽材料帶入另一個新的研究領域 ，也引起學界相當大的興趣；在這篇論文裡，我們針對多孔矽的基本特性做了進一步 的研究，並將這些特性，應用到元件的製作上。 基本特性的探討包括：多孔矽與多孔矽發光特性的關係、多孔性與多孔層厚度的關係 以及多孔層電性的研究，由這些特性的研究得知，藉由電解條件的控制，可以調整多 孔矽孔洞的大小，進而控制多孔矽的光激發波長，換言之，多孔矽是一種具有發出各 種可見光波長潛力的材料，另由電性的研究知，多孔矽內的摻雜濃度與本質半導體之 濃度非常接近。 多孔矽的應用，則包括：黃橙光及藍光多孔矽發光二極體，和寬頻、高怠度的光怠測 二極體，雖然藍光多孔矽發光二極體的發光效率仍低，然而卻是多孔矽應用的一項重 要突破，而其與黃橙光多孔矽發光二極體最大不同處便在於多孔矽的1100℃高溫處理 過程，不僅使易傾倒的silicon wire因氧化而穩固，並且因尺寸的縮小而發出藍光； 玉於多孔矽光怠測器二極體，則是利用多孔矽孔洞的大小的分佈、多孔層厚度的可調 變性、結構化的多孔矽表面及多孔層的位置，使得多孔矽光感測器具有寬頻、高感度 的潛力。
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Zheng, Qing-Feng, and 鄭清峰. "Patterned Porous Silicon Etching On PN-type Silicon Substrate." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/36832224786671598111.
Full textAbstract:
碩士聖約翰科技大學
電子工程系碩士班
101
In this study, the sample silicon substrate (N-Epi on P-sub type) was first engraved to different pattern of 90μm depth by using laser engraving machine, and then etched 15 minutes to form the porous silicon substrate with a constant current 0.01A. We observed and recorded the appearance of the porous silicon substrate with different pattern under fluorescent light projection, as well as the optical excitation light colors under 365nm wavelength UV light projection. In addition, emission spectra and relative intensity of the different patterns on the porous silicon substrate were recorded by using a photoluminescence (PL) spectrum analyzer. Tiny structures of porous silicon surface were observed by applying the 3D surface profiler, field emission scanning electron microscope and scanning electron microscopy. Experimental results show that while the laser engraved depth in sample silicon substrate deeper than PN junction and formation of closed pattern, limit etching phenomenon of pattern will happen, however, non-closed pattern does not have this phenomenon. The limit-etching occurrence situations of various pattern used in this study are all beginning with a small area, and then gradually form a large area etching. Meanwhile, we also have observed that the surface roughness and the porous structure in the closed area are more obvious than the outside area. The porous silicon of various patterns can be effectively and quickly formed with this method. We hope that the smaller graphical porous silicon can be formed in the future for facilitating the use of other components and the research of application.
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Gau, Yang-Jer, and 高揚哲. "Fabrication and characterization of porous silicon." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/58707992973341275407.
Full textAbstract:
碩士國立交通大學
光電(科學)研究所
83
To perform the fabriaction and characterization of porous silicon is the goal of this thesis. In experiment, we find that the thermal conductivity of porous silicon is 2.8 W/m‧℃ ,which is as smaller as a factor of 53 than crystalline silicon. Hence, the porous silicon can be used as a isolating plate in thermal microsensors. Using this technique, a thermal pad with lower stress and higher yield will be achieved.
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Syu, Bo-Jhih, and 許博智. "Graphical Porous Silicon Optical Sensing Element." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/20749721710142833979.
Full textAbstract:
碩士聖約翰科技大學
電子工程系碩士班
101
In this thesis, the main use of laser engraving machine, the porous silicon experiments graphical two thicknesses of 525 μm and 230μm P-type silicon, experimental preparation before the coupons will be clean, then the surface of the specimen with Blue Tape lamination on, laser engraving machine engraving graphics on Blue Tape, 5 each triangle, round, square, carved out of the basket empty graphics, The total area of each graphic shape are 3 mm2 of parallel electric current disparity under etching experiment and analysis. After the experiment, of record test piece under the UV lamp 254 nm and 365 nm bands of light irradiation, the color of the light of the excitation light, spectrum analyzer (Maple PL), observation of the luminescence of porous silicon in the graphic relative intensity and band distribution range, to observe the surface structure of graphics inside the porous silicon and then a scanning electron microscope (Scanning Electron Microscope, SEM), measurement using 3D surface profiler (3D Profile) structure and roughness and depth, then I-V measurement instrument, Four cases in fluorescent lamps, black box, halogen lamps, and UV light, etc. Electrical characteristic curve analysis progress. Specimen thickness of 230 μm, pattern is triangular, the concentration ratio of 1:2, the constant voltage, the time is 15 minutes resistance change, Due to the specimen thickness of 230 μm columnar, the thickness of the specimen will affect the structure of the porous silicon; different graphics under current the corner of the etching, lead to the corner of the porous silicon is less; etching concentration ratio of 1:2 porous silicon plate and columnar structure significantly, Etching a concentration of 1:3, only cracks The etching time was 15 minutes excited by the light intensity of light, in the future Laser engraving machine engraving more complex graphics can be used. Keyword : Laser engraving machine, I-V measurement instrument, Electrical characteristic curve.
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Weng, Jia-jiun, and 翁嘉均. "Reaearch of Porous Silicon Micro-Structure." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/80527950072019001837.
Full textAbstract:
碩士國立中山大學
光電工程研究所
94
Photo luminescence of C545T and NPB on porous Si was studied. The porous Si structures were obtained by anodic dissolution of p-type Si in a concentrated HF solution. Pore diameter of 100Å and pore layer of a thickness around 0.5μm were formed by varying the electrolytic condition, including HF concentration, anodiztation time, electrolytic current and voltage. The photo luminescence of C545T and NPB were investigated by depositing them onto the porous Si substrate using spin coating, dipping with ultrasonic agitation and thermal evaporation techniques. The photo luminescence of C545T and NPB were found to peak around 580nm and 440nm for samples prepared by spin coating. However, for NPB samples deposited by dipping with ultrasonic agitation and thermal evaporation, additional photo luminescence peak at 430nm were observed. SEM photos analysis confirm that the organic materials can diffuse into the Si pores by ultrasonic agitation and deposition in vacuum.
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Chang, Tsung-Hao, and 張淙豪. "A Study on Porous Silicon Etching." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/59474136927369164515.
Full textAbstract:
碩士國立清華大學
電子工程研究所
91
The anodic etching of silicon in HF solution is a useful technique for MEMS(Micro-electrical Mechanical Systems) . We can use some structures or characters of porous silicon for MEMS technology. This paper studies how different porous silicon generalized by different masks, and uses the Double-side technique to improve undesired lateral etching during processing. Consequently, it has been demonstrated that porous silicon layers can be formed completely through the thickness of a 500 um wafer, and even thicker one.
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LIEN, CHI-CHUN, and 連啟淳. "Study on Electroluminescence of Porous Silicon." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/4kz62e.
Full textAbstract:
碩士國立臺北大學
電機工程學系
107
In recent, light-emitting diode(LED) is one kind of fluorescent compositions which consists of chemical element III-V, and is generally used in lighting and display. Up to now, LEDs have many advantages, including high efficiency, lower energy consumption and longer lifetime. Besides, the range of LEDs’ development starts from visible light to ultraviolet light. But the cost of LED is still higher than other traditional illumination component. Compared to the light-emitting element based on porous silicon, which takes advantage of simple process, low cost and low power consumption. The part of thesis focus on not only the photoluminescence(PL) under ultraviolet (UV) light with the wavelength pitched at 365 nm, but also the electroluminescence(EL) with different types of porous silicon structure made from Si wafer of p-type, n-type and pn-type. The purpose of this thesis is to analysis the EL luminescent properties of each type of Si wafer, including turn-on voltage, luminescent efficiency, and electroluminescence duration. The thesis describes the influences of electroluminescent properties caused by different etching factors on three types of Si wafer. The LED components made from porous silicon ensure smooth operation at room temperature. With DC voltage, the wavelength of visible light within the range between 540 nm to 740 nm while the minimum power consumption is 1mW.