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Purpose The purpose of this study is to address the issue of technology equipment formerly dedicated to the process of 4- and even 5-inch photovoltaic cells and whose use has become critical with the evolution of silicon wafer size standards (M2–M10). Fortunately, the recent concept of 6'' half-cut cell with its many advantages appears promising insofar as it offers the possibility of further extend the use of costly, still operational process equipment, but doomed to obsolescence. Design/methodology/approach In the background of a detailed Al-BSF process, the authors show how to experimentally adapt specific accessories and arrange 6” half-wafers to enable the upgrade of a complete industrial process of silicon solar cells at a lower cost. Step by step, the implementation of the processes for the two wafer sizes (4” wafers and 6” half wafers) is compared and analyzed in terms of performance and throughput. Findings Globally, the same process effectiveness is observed for both types of wafers with slightly better sheet resistance uniformity for the thermal diffusion carried out on the half wafers; however, the horizontal arrangement of the wafer carriers in the diffusion and the plasma-enhanced chemical vapor deposition tubes limits the thermal balance regarding the total number of cells processed per batch. Originality/value In terms of the development of prototypes on a preindustrial scale, this paves the way to further continue operating outdated equipment for high-performance processes (passivated emitter and rear contact, Tunnel oxide passivated contact (TOPCon)), while complying with current standards for silicon wafers up to M10 format.

To get enhanced long-wavelength absorption, an impurity photovoltaic (IPV) mechanism was implemented within a transparent conducting oxide (TCO) at the rear of a solar cell. The numerical simulation of the N+/P (silicon)/IPV-TCO device was carried out by using SCAPS-1D program which allows the inclusion of optically active defects. In the proposed heterostructure configuration, ZnTe is a suitable material as back surface reflector. In analyzing the Si/ZnTe interface, lattice mismatch, energy band alignment and defects density were considered with appropriate treatment. In particular, to cure the detrimental 12% lattice mismatch at the interface, a thin silicon amorphous layer was inserted in-between, allowing 22.98% conversion efficiency. With adapted ZnTe Lucovsky's model for the optical capture cross sections and introduction of an oxygen radiative IPV defect (O2 level at 0.4 eV below the conduction band), a conversion efficiency of 27.15% was ultimately achieved. The experimental feasibility of the high-efficiency heterostructure device is evaluated.

TiOxNy films were grown onto 316L stainless steel substrate using radiofrequency (rf) magnetron sputtering from a pure titanium nitride target in Ar–O2 gas mixture with various substrate bias voltages. The aim of this work is to investigate the effect of applied substrate bias Vs, varied from 0 to –100 V, on the deposition rate, structure, hardness and optical properties of the TiNxOy films. The characterization of the coatings by grazing incidence X-ray diffraction exhibited a crystalline structure of a mixture of TiN, rutile and anatase. The indirect and direct bad gap were found to decrease for unbiased substrate voltage to Vs = −100 V from 3.84 to 3.20 eV. In addition, the coatings exhibit high transparency (transmittance over 80%). The hardness of the coatings were found in the range of 6.2 to 12.5GPa.

Up to date, the absorber low grain growth and the secondary compound formation remain the main factors causing the poor performance of kesterite solar cells based on spray pyrolysis derived Cu2ZnSnS4 (pure sulfide CZTS = PS-CZTS) compared with other deposition techniques. As the sodium (Na) inclusion is known to play a crucial role in affecting the grain growth, we evaluated in this report a thorough investigation in depth of the effect of Na doping content on crystallinity and phase segregation. The PS-CZTS was deposited by ultrasonic spray pyrolysis while the Na incorporation was carried out by soaking the pre-heated sprayed films in a solution of an environmentally-friendly NaCl salt. The change in the investigated parameters was followed throughout the absorber by scanning electron microscopy, Raman spectroscopy with different excitation wavelengths, grazing incidence X-ray diffraction (GIXRD) with various incidence angles, energy dispersive X-ray spectroscopy (EDS), secondary ion mass spectrometry (SIMS) and UV–Vis spectrometry. Increasing Na content significantly improves the crystallinity and the compactness simultaneously, resulting in smoothest surfaces with grains up to 2 µm in size. The Na was uniformly diffused leading to similar grain growth throughout the films. Whatever the Na content, the deposited materials are mostly consisting of ketserite-type PS-CZTS, whereas the use of different Raman excitations reveal the presence of Cu2S, ZnS and ZnO as secondary compounds in trace forms. The depth profile analysis with GIXRD showed that no further phase segregation has occurred while the EDS and SIMS results showed uniform distribution of PS-CZTS′ constituents along the surface and within the deposited films. By combining Raman, GIXRD and EDS analysis, the secondary compounds were found to be mostly gathered in the upper absorber layer. The absorption coefficient and the band gap range around 104 cm−1 and 1.55 eV respectively, the optimal values required for photovoltaic energy conversion. The Na doping developed in this study has a promising potential to yield high quality sprayed absorbers and opens up access to opportunities in enhancing of sprayed PS-CZTS thin film solar cell performances.

Aluminum oxide (Al2O3) films of different thicknesses were deposited on quartz and silicon (100) substrates by an ultrasonic spray method from a solution of aluminum acetylacetonate dissolved in N,N-dimethylformamide with different molar concentrations. The optical, morphological and electrical properties were investigated. Increasing the molar concentration leads to a refractive index decrease, an increase in the optical band gap from 5.26 eV to 5.52 eV and a change in the surface roughness of the films. The electrical parameters at the Al2O3/Si interface such as the flat band voltage (VFB), effective charge density (Qeff) and interface trap density (Dit) were explored as a function of the molar concentration, film thickness and heat treatment. The latter, done by two annealing processes, namely, the post deposition annealing (PDA) and post metallization annealing (PMA) on the structure, lead to remarkable interface properties. It was found that the positive flat band voltage VFB shift is correlated with the generation of negative effective charge during PMA. A decrease of the Dit distribution in the PMA samples with no significant effect in the case of PDA samples was clearly observed for different molar concentrations. Furthermore, as the Al2O3 film thickness decreases, Dit decreases in both PDA and PMA samples while the relatively high density Qeff and its negative charge polarity were obtained for thinner films. A noticeable passivation effect on the Al2O3/Si interface has been confirmed on samples that underwent the annealing process. These findings related specifically to the interface properties are promising for silicon surface passivation, in particular for solar cells applications.

To reduce the risk of intra-stent restenosis and improve hemocompatibility of biomaterials, the therapeutic re-endothelialization is required. Indeed, the behavior of endothelial cells is affected by several factors such as wettability and surface energy of biomaterial in contact with cells and blood. The aim of this study was to evaluate the physicochemical and biological properties of new polymers derived from poly((R,S)-3,3-dimethylmalic acid) (PDMMLA) that will be used as cardiovascular stents coating. In fact, a comprehensive study of the roughness and topography and the thermal and rheological properties of these materials were investigated. Furthermore, this was correlated with the biological response of human vascular endothelial cells (HUVECs) and monocytes (MM6) to these biomaterials. Our results revealed very interesting surface properties of PDMMLAs, excellent thermal and thermo-mechanical properties and a suitable biological response. All these properties can be adjusted by simple chemical modification of the side chain of the studied polymers.

The physical and photo-electrochemical properties of the hetero-junction Al/TiO2 layers grown on quartz substrate by Spray Ultrasonic Method (SUM) were studied. The Grazing Incidence X-Ray Diffraction (GIXRD) exhibits narrow lines belonging to the anatase structure with a quadratic symmetry and a good crystallinity, a result confirmed by the Raman spectroscopy. The direct optical transition (3.34 eV) permits to exploit photo-electrochemically the solar UVA radiation; another transition indirectly allowed is observed at 2.92 eV. The capacitance-potential graph, plotted in Na2SO4 electrolyte, shows that TiO2 acts as n-type semiconductor with a flat band potential (Efb) of −0.27 V and a donor concentration (ND) of 1.2 × 1021 cm−3 due to oxygen vacancies. The conduction band (−0.66 VSCE) deriving from Ti4+: 3d orbital, is more negative than the level O2/O2•- (−0.4 VSCE). Therefore, the excited electrons are channelled to Al auxiliary electrode, leading to reduce oxygen into O2•- radicals, for the mineralization of the Rhodamine B (Rh B) at free pH (~ 7). The electrons transfer is facilitated through the bi-functional hetero-junction, due to the low over-voltage onto Al. An abatement of 30% (Rh B, 10 ppm) within 4 h of solar irradiation is obtained.

Titanium oxide (TiO2) films have been synthesized on quartz, silicon and textured silicon substrates by chemical ultrasonic spray deposition. The textured silicon substrate was carried out using Na2CO3 solution. The sample surface exhibits uniform pyramids with an average height of 5 µm. In this paper, particular attention is given to the TiO2 films prepared by spray ultrasonic system using Tetra iso-Propoxide Orthotitanate Titanium (TPOT) as a precursor. The solutions were sprayed onto substrates heated at various temperatures 350 - 550 °C. The properties of films as a function of temperature parameter were investigated using structural and optical analysis. According to XRD, FTIR and Micro-Raman spectroscopies, the anatase phase was found and exhibits nanograins of 9 to 15 nm in size. The indirect and direct bad gap were found to increase by increasing substrate temperature due to the decreasing of nanograins size and were estimated to be around 3.28 and 3.38 eV. A transmittance higher than 80% was found. This paper reports on anti-reflection coating application of TiO2 layers due to its good transparency and appropriate refractive index varies between 2.19 - 2.40 at λ = 632.8 nm as a function of temperature determined by UVVisNIR spectrophotometer and Ellipsometry. To achieve optimum anti-reflection characteristics different anti-reflection designs were experimentally examined with polished and textured substrates. The average reflectance of the polished silicon used in this study is 39%, with TiO2 it decreases to 9%. The textured surface reduces the average reflectance of silicon to be around 14% and it decreases dramatically to 5% after deposition of a single layer of TiO2 as an anti-reflection coating. The gain in density of the short-circuit photocurrent assigned to the reduction of reflection losses up to 44% and 58% were predicted with TiO2 single-coating in polished and textured silicon substrates respectively.

TiO2 thin films are of paramount importance due to their pervasive applications. In contrast to previous published works where the substrate was heated at high temperatures to obtain TiO2 crystalline phase, we show in this study that it is possible to deposit crystalline TiO2 thin films on biased and unbiased substrate at room temperature using reactive rf magnetron sputtering. The bias voltage was varied from 0 V to −100 V. The deposited films were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy, Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS) and atomic force microscopy (AFM). The average crystallite size was estimated using x-ray diffraction. The results showed that the application of negative bias affects the surface roughness of the films and favors the formation of the rutile phase. The root mean square roughness (Rrms), the average grain size and the optical band gap of the films decreased as the substrate bias voltage was varied from 0 to −100 V. The UV–visible transmittance spectra showed that the films were transparent in the visible range and absorb strongly in the UV range. This study shows that biasing the substrate could be a promising and effective alternative to deposit TiO2 crystallized thin films of engineered properties at room temperature.

Summary The Nyalau Formation constitutes major Cycles I to III reservoirs in the offshore Balingian Province, Sarawak Basin, NW Borneo. Current understanding of its’ reservoir quality in the onshore Central Sarawak is relatively vague as previous works were focused mainly on outcrops studies. In this study, Cycle I sequences penetrated by a drilled well was studied to understand reservoir quality and predict fluid-flow controls. The reservoir units were sourced dominantly from recycled orogenic sandstones provenance (ROSP) and petrophysically tight (ɸ< 10%; K< 1mD) at shallow depth (1037 Feet), and the poro-perm datasets correlate to identified facies. Adopted realistic petrophysical model suggests that porosity loss resulted mainly from compaction with less contribution from cementation, as indicated by clustering of estimated 64.3% of the reservoir samples. This cluster has lost ca. 30 to 63% of their initial porosity due to mechanical compaction. Elemental and mineralogical datasets yielded useful downhole correlation with poro-perm variation. Early to intermediate diagenetic events characterise. Overall, our data imply that ROSP- sourced siliciclastic reservoir experience significant poro-perm loss at a relatively shallower depth. Hence, understanding reservoir provenance is essential to minimise exploration risks.

The zirconia (ZrO2) films were deposited using radio-frequency magnetron sputtering (RFMS) from a pure zirconium target in Ar-O2 gas mixture with different percentage of the oxygen. The effect of Oxygen percentage on the film’s characteristics was investigated by Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and tribology test. Also, the contact angle of the films was measured in order to evaluate their hydrophobicity. Additionally, in vitro test in artificial blood plasma and further SEM observations were performed to study bioactivity of the films. The experimental results showed that the roughness, the porosity and the thickness of the films depend on the oxygen percentage. According to XRD and Raman spectroscopy results, the films present a polymorph phase of monoclinic and tetragonal. Zirconia films at low oxygen percentage showed better hydrophobic behavior with 114.5° at 15% of oxygen. These films also exhibit a lower friction coefficient and wear rate (0.22 and 6 × 10−07 mm3/m respectively). However the best bioactive behavior was exhibited by the films deposited at 25% of oxygen due to their higher roughness and porosity. In fact, it was found that the bioactivity of the films is highly dependent on the porosity and roughness of the films.

ZnS/Si/CuO heterostructure is investigated by a theoretical approach as a possible low-cost design for photovoltaic conversion in the track of the heterojunction with intrinsic thin layer solar cells. Our results indicate that, owing to perfect electron affinity and lattice matching properties, zinc sulfide with adequate Al doping can efficiently replace zinc oxide window layer as an emitter region for silicon-based solar cells. Lattice mismatch, energy band alignment at the interfaces and material resistivity are the framework parameters of the study. By focusing on the open circuit voltage parameter, the back metal/Si and silicon base doping were optimized so that the conversion efficiency was increased from 3.37% to 15.19%. The introduction of a cupric oxide (CuO) layer acting as a p + back surface field with a bandgap of 1.35 eV and appropriate doping as high as 7 × 1018 cm−3 can enhance the conversion efficiency to 17.30%, provided that the silicon material remains free from contamination by copper atoms and also by performing a suitable treatment of CuO to lower its resistivity.

Ultrasonic spray pyrolysed CuxZnSnS4 (CZTS) thin films with different copper ratios (x = 1.6, 2, 2.4 and 2.8) were successfully deposited on microscopic glass substrates from an aqueous solution of CuCl2 2H2O, ZnCl2, SnCl2 and thiourea. The deposited films at substrate temperature of 310 °C were heat treated up to 500 °C under N2 gas flows with and without sulfurization process (under sulfur vapor flow ). The effect of the both copper ratio and sintering atmosphere on structure, morphology, optical and electrical properties was studied by Raman scattering, AFM observations, ultraviolet-visible absorbance spectroscopy and Four Point Probe. Results showed that after sulfurization, the crystallization of samples with x=2 and 2.8 in CZTS kesterite structure is improved while the Cu- enriched film featuring larger grains in the range of 100 nm in size. The optical band gap ranges from 1.4 to 2 eV while the film with the stoichiometric composition (x=2) showed the lowest value. The sheet resistance drops significantly in all sulfurized samples and the lowest value of 131 Ohms was reached with the stoichiometric composition (x=2).

Remodelling of the membranes and protein clustering patterns during the pathogenesis of cardiomyopathies has renewed the interest in spatial visualisation of these structures in cardiomyocytes. Coincidental emergence of single molecule (super-resolution) imaging and tomographic electron microscopy tools in the last decade have led to a number of new observations on the structural features of the couplons, the primary sites of excitation-contraction coupling in the heart. In particular, super-resolution and tomographic electron micrographs have revised and refined the classical views of the nanoscale geometries of couplons, t-tubules and the organisation of the principal calcium handling proteins in both healthy and failing hearts. These methods have also allowed the visualisation of some features which were too small to be detected with conventional microscopy tools. With new analytical capabilities such as single-protein mapping, in situ protein quantification, correlative and live cell imaging we are now observing an unprecedented interest in adapting these research tools across the cardiac biophysical research discipline. In this article, we review the depth of the new insights that have been enabled by these tools toward understanding the structure and function of the cardiac couplon. We outline the major challenges that remain in these experiments and emerging avenues of research which will be enabled by these technologies.

Sol-gel x TiO 2 (100 − x )SiO 2 nanocomposite thin films with x = 0, 25, 50, 75 and 100 mol % were dip-coated on glass and silicon substrates. The influence of the composition on structure, morphology and optical properties was studied by X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electronic microscopy, monochromatic ellipsometry at λ = 632.8 nm and ultraviolet–visible absorbance spectroscopy. The optical properties were discussed on the basis of the microstructure. After annealing at 500 °C, results showed high pure materials, homogenous crack-free surfaces with good adherence and high optical qualities. The 100% TiO 2 crystallizes in the anatase phase and exhibits nanograins of 6 to 10 nm in size. However, all the other compositions are amorphous with comparable grains around 4 nm in size. The averaged transmittance decreases with increasing the TiO 2 content but remains higher than 90%. Whatever the composition, the coating thickness increases linearly as the withdrawal speed increases from 10 to 54 mm/minute. The relationship between refractive index and composition was analyzed by fitting the experimental data to different theoretical models for the refractive index of mixed films. Results showed that depending on the withdrawal speed, the data can properly fit either the Drude or the linear models. Thus, the film thickness can be adjusted by the control of the withdrawal speed. However, the control of the composition allows easily the tuning of the refractive index from 1.48 to 2.18 at λ = 632.8 nm to achieve optimum anti-reflection characteristics. Different anti-reflection designs of both single and double layers were experimentally examined. Gains (assigned to the reduction of reflection losses) up to 54 and 63% were predicted with 75% TiO 2 single-coating and SiO 2 /TiO 2 double-coatings respectively.

We investigated the structural; optical and electrical properties of ZnO thin films as the n-type semiconductor for silicon a-Si:H/Si heterojunction photodiodes. The ZnO film forms the front contact of the super-strata solar cell and has to exhibit good electrical (high conductivity) and optical (high transmittance) properties. In this paper we focused our attention on the influence of doping on device performance. The results show that the X-ray diffraction (XRD) spectra revealed a preferred orientation of the crystallites along c -axis. SEM images show that all films display a granular, polycrystalline morphology and the ZnO:Al exhibits a better grain uniformity. The transmittance of the doped films was found to be higher when compared to undoped ZnO. A low resistivity of the order of 2.8 × 10 −4 Ω cm is obtained for ZnO:Al using 0.4 M concentration of zinc acetate. The photoluminescence (PL) spectra exhibit a blue band with two peaks centered at 442 nm (2.80 eV) and 490 nm (2.53 eV). It is noted that after doping the ZnO films a shift of the band by 22 nm (0.15 eV) is recorded and a high luminescence occurs when using Al as a dopant. Dark I – V curves of ZnO/a-Si:H/Si structure showed large difference, which means there is a kind of barrier to current flow between ZnO and a-Si:H layer. Doping films was applied and the turn-on voltages are around 0.6 V. Under reverse bias, the current of the ZnO/a-Si:H/Si heterojunction is larger than that of ZnO:Al/a-Si:H/Si. The improvement with ZnO:Al is attributed to a higher number of generated carriers in the nanostructure (due to the higher transmittance and a higher luminescence) that increases the probability of collisions.

A ZnO thin film was successfully synthesized on glass, flat surface and textured silicon substrates by chemical spray deposition. The textured silicon substrate was carried out using two solutions (NaOH/IPA and Na2CO3). Textured with Na2CO3 solution, the sample surface exhibits uniform pyramids with an average height of 5 μm. The properties and morphology of ZnO films were investigated. X-ray diffraction (XRD) spectra revealed a preferred orientation of the ZnO nanocrystalline film along the c-axis where the low value of the tensile strain 0.26% was obtained. SEM images show that all films display a granular, polycrystalline morphology. The morphology of the ZnO layers depends dramatically on the substrate used and follows the contours of the pyramids on the substrate surface. The average reflectance of the textured surface was found to be around 13% and it decreases dramatically to 2.57% after deposition of a ZnO antireflection coating. FT-IR peaks arising from the bonding between Zn–O are clearly represented using a silicon textured surface. A very intense photoluminescence (PL) emission peak is observed for ZnO/textured Si, revealing the good quality of the layer. The PL peak at 380.5 nm (UV emission) and the high-intensity PL peak at 427.5 nm are observed and a high luminescence occurs when using a textured Si substrate.

The structure and photoluminescence (PL) of ZnO films deposited on Si (111) substrates by chemical spray deposition using aqueous solution of zinc acetate [Zn (CH3 CO2)2 , 2H2O] was investigated. It was found that these properties depend strongly on growth temperature and grain size. The samples grown at the optimum deposition conditions can generate stronger luminescence. It was revealed by X-ray diffraction that the preferred orientation of poly-crystals is along C-axis, with hexagonal wurtzite structure. PL spectroscopy results shows an evident ultra-violet (UV) emission observed near 380 nm with a broad low intensity band centred at 430 nm. The band was reported as being caused by the defects in the grain boundaries of ZnO. Under optimum deposition conditions a low resistivity and a high optical transmittance of the order of 2.8×10−4 Ω cm and 90%, respectively, were obtained.

Application of thin films of SiO2 and TiO2 using the sol-gel process were utilized as antireflection coating on monocrystalline silicon wafers. The aim of this study is to validate this process as a procedure to prepare antireflective films for monocrystalline silicon by dip-coating. The coating was carried out by dip-coating process using tetraethoxysilane (TEOS) as precursor for SiO2 and titanium isopropoxide (TIPT) as precursor for TiO2. In order to study the influence of the thickness on the reflectance and the optical parameters, several coatings with different thickness were deposited onto silicon wafers. The refractive index and the thickness were adjusted by controlling the number of dipping. The refractive index increases from 2.10 up to 2.22 by increasing the film thickness from 36 to 137 nm. It was found that the sample coated with two layers exhibits a lower reflection (1.86 % at λ = 602 nm). This result was improved by a single sub-layer of SiO2 (36.75 nm) to reach 1.08 % at λ = 674 nm). Furthermore, the low values of the extinction coefficient (k) (approach to Zero at λ = 632.8 nm) indicate that TiO2 and SiO2 films deposited by sol-gel method can be used as ARC for Si solar cells.

The thermal annealing behavior of the SnO2 thin films elaborated by sol-gel method has been studied by the neutrons reflectivity technique. From the fit of the experimental data using Parratt32 software program developed at HMI, Berlin, scattering length density, thickness and roughness are extracted. The obtained results show that the film thickness increases with the increasing annealing temperature, and the roughness is higher at 500 °C. Whereas, approximately, the same scattering length density is obtained after each annealing temperature.

International audience; Nanocomposite TiO2-SiO2 thin films with different compositions (from 0 to 100 mol% TiO2) were deposited by sal-gel dip-coating method on silicon substrate. Crystal structure, chemical bonding configuration, composition and morphology evolutions with composition were followed by Raman scattering, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy and scanning electron microscopy respectively. The refractive index and the extinction coefficient were derived in a broad band wavelength (250-900 nm) from spectroscopic ellipsometry data with high accuracy and correlated with composition and microstructure. Results showed an anatase structure for 100% TiO2 with a grain size in 6-10 nm range. Whereas, the inclusion of SiO2 enlarges the optical band gap and suppresses the grain growth up to 4 nm in size. High TiO2 dispersion in SiO2 matrix was observed for all mixed materials. The refractive index (at lambda = 600 nm) increases linearly with composition from 1.48 (in 100% SiO2) to 2.22 (in 100% TiO2) leading to lower dense material, its dispersion being discussed in terms of the Wemple-DiDomenico single oscillator model. Hence, the optical parameters, such optical dispersion energies E-D and E-d, the average oscillators, strength S-0 and wavelength lambda(0) and the ratio of the carrier concentration to the effective mass N/m* have been derived. The analysis revealed a strong dependence on composition and structure. The optical response was also investigated in term of complex optical conductivity (sigma) and both volume and surface energy loss functions (VELF and SELF).

A matched triaxial device is developed and constructed to measure the transfer impedance of braided coaxial cables at microwave frequencies. Full-design principles of the device have been developed and given in detail in the paper. The device is particularly suited for shielding measurements at frequencies up to 3.5 GHz, for which no comparable technique exists. The performance of the device is fully evaluated both theoretically and by measurements. The accuracy of the device is studied by comparing the results against those obtained from the low-frequency International Electrotechnique Committee triple-coaxial apparatus, and using well-known theoretical models.

A matched triaxial device is designed and constructed to measure the transfer impedance of braided coaxial cables at UHF frequencies. Full design principles of the device have been theoretically developed and the details were given in the paper. The device is particularly suited for accurate measurements of transfer impedances at higher radio frequencies up to 3.8 GHz, for which no comparable technique exists. The performance of the device is evaluated by comparing the results against those obtained from low frequency IEC’s triple coaxial apparatus and those obtained by using well known theoretical models.

A new method for modeling the electromagnetically coupled substrate noise from digital gates in large mixed-signal integrated circuits was developed. The unique feature of the method is that it employs a modular approach to model noise coupling via current injection from the digital gates which alleviates the problems associated with the current methodology in so far as the circuit size, instability the effects of parasitics and the accuracy issues are concerned. The method was demonstrated on the characterization of the substrate noise issues in FLASH analog-to-digital (A/D) converters. The model was then used to study the addition of the p/sup +/ guards around the input devices of comparators in order to asses their effectiveness in reducing the substrate noise. The effect of variations in the package bond-wire inductances in the net injected current noise was also modeled.

A method for modelling electromagnetically coupled substrate noise in mixed signal integrated circuits was developed. This method was then used to characterise the substrate noise issues in FLASH analogue to digital (A/D) converters. The model was also used to study the addition of the P+ guards around the input devices of the comparators in order to assess their effectiveness in reducing the substrate noise. Finally, the effect of variations in the package's bond wire inductances in the net injected current noise was modelled.

The measured self-field AC power dissipation in superconducting BiSrCaCuO-2223/Ag tapes and a prototype cable is compared with theoretical models. A brief overview of the theoretical background for AC loss calculations in superconductor tapes with different geometrical shapes is given. New models for the harmonic components of the fundamental frequency and the current dependent nonlinear inductance are also derived. It is shown that the latter models can be used to estimate current distribution and the variation of flux penetration in superconducting tapes. Two separate experimental apparatus were designed and constructed for measurements on tapes and prototype cable systems. The observed losses in tapes are reasonably well described by models based on the critical state model. In contrast, the measured losses in the prototype cable are found to be a factor of approximately two higher than the predicted values. Further investigations showed that this may be due to inhomogeneous contact resistance between individual tapes and the current joints and the variation in critical current density distribution between tapes. The significance of current dependence of the loss component, inductive quadrature component, phase error in measurements and the definition of the critical current in the prototype cable are also discussed.

Noise caused by the electromagnetic coupling of digitally injected signals into substrate is a key problem in the design of large mixed-signal circuits. This paper describes methods which allow the circuit designers to efficiently model such substrate noise in large mixed-signal SPICE designs. With the help of these techniques a new methodology is developed for efficiently modelling the current injected electromagnetic noise in the substrate and its coupling to analogue signals. The new method is then extended to provide real time modelling capability. The practicality and the numerical efficiency of the methods are demonstrated on several example circuits.