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The purpose of this study is to identify parameters that affect the rate of sound transmission loss. Mathematical model of sound transmission loss (STL) is developed for laminated glass and maximize the STL of laminated glass by using response surface methodology (RSM). The main objective of this study is to determine the type of material and number of interlayers for laminated glass on the STL performance. The two-load transfer function method (TFM) coupled with LMS Test Lab Acoustic software to determine the STL. The analysis was made by observing the performance of STL with respect to different materials used, such as glass and Perspex. Besides that, number of interlayers for laminated glass also had been studied for the performance of STL. Next, the RSM will be applied to develop mathematical modelling of STL for laminated glass. Optimization on the variable of laminated glass also has been conducted to obtain optimum variable of laminated glass in order to deliver optimum STL performance.

The main objective of this study is to maximize the rate of sound absorption by applying the parameters of micro-perforated plate (MPP) such as the holes diameter, holes spacing, thickness of MPP, and air cavity depth of MPP. In this study, an optimization algorithm – Firefly algorithm is adopted to determine an optimum set of four parameters for MPP. There are four pieces of MPP with different holes of diameter and spacing was used as specimens. The two-microphone impedance tube method was used to measure sound absorption coefficient (SAC) of MPP sound absorber according to ASTM E1050-12 standard. From the experiments, MPP C (hole diameter = 0.5 mm, hole spacing = 7 mm) for both air cavity depth (30 & 60 mm) score the highest SAC which is 1.00 while MPP B (hole diameter = 0.9 mm, hole spacing = 5 mm) obtain the lowest SAC for air cavity of 30 and 60 mm, which are 0.62 and 0.54 respectively. Then, the firefly algorithm is applied to obtain the optimal solution the set of parameters for MPP sound absorber to reduce the noise level. Hence, it is concluded that by increasing the air cavity depth, holes spacing, and decreasing holes diameter size can increase the rate of sound absorption for MPP. The optimal set of parameters obtained from this study for MPP sound absorber for air cavity, hole diameter and holes spacing are 30, 0.71 mm and 0.5 respectively.

In this work, we investigate an fabricating route of solution-processed thin-film transistors (TFTs). The high-k dielectric layers of aluminum oxide (AlO) were optimized through hydrogen peroxide (H 2 O 2 ). With Zn incorporation in tin oxide (SnO) semiconductor layer, the ZnSnO TFT with a field effect mobility of 4.3 cm2·V−1·s−1, a threshold voltage of 2 V, a subthreshold swing of 0.16 V/dec and an on/off ratio of 106.

In this work, the Ni/AlO x /Pt RRAM device was fabricated with solution-processed AlO x thin film at different annealing temperatures (150/200/250/300/350°C). The supreme electrical performance and stable operation of device has been achieved demonstrating resistive switching characteristics at 250°C, including SET operation voltage lower than 1.5 V, narrowest resistance distribution, retention time longer than 104 s and endurance over 102 cycles. The results reveal the effect of dielectric fabrication temperatures for RRAM device and demonstrate the prospect of solution-processed methodology.

In this study, we describe how to obtain high-quality Al 2 O 3 dielectric thin films and their implementation in In 2 O 3 thin film transistors by combining plasma treatment and combustion process at low temperatures (250 °C). The single layer Al 2 O 3 dielectric formed by this technique exhibited a higher areal capacitance and a lower leakage level compared with those of conventional solution-processed Al 2 O 3 . The resulting TFTs presented a superior electrical performance at a low operating voltage of 2 V, with a positive threshold voltage of 0.39 V, a subthreshold swing of 0.V/decade, an On/Off ratio of 1.8×104, and a superior mobility of 136 cm2 V−1 s−1.

In this work, we investigate an eco-friendly route of fabricating solution-processed thin-film transistors (TFTs). With Li incorporation in the indium oxide (InO) semiconductor layer, the annealing temperature can be lowered to 200°C. The combination with a solution processed high-k aluminum oxide (A1O) dielectric layer, produces a TFT field effect mobility with average value of 20.5 cm2·V−1·s−1 from 30 samples, which is a promising result for future applications.

In this study, we develop a simple and eco-friendly aqueous route for the fabrication of sodium (Na) doped ZnO/AlO x thin-film transistors (TFTs). To prepare Na doped ZnO and AlO x thin films, ammonia water and deionized water were used as the precursor solvents. The A1O x thin film annealed at 300°C showed an areal-capacitance of 129 nf/cm2 at 1 kHz. On the basis of its implementation as the gate oxide, fully solution-processed Na doped ZnO TFTs were fabricated and the electrical characteristics were systematically studied. The fully solution processed Na doped ZnO/ A1O x TFTs exhibited a high field effect mobility of 21 cm2 V−1 s−1, a subthreshold swing of 0.58 V/decade, a threshold voltage of 0.8 V, and an on/off current ratio of 2×104.

In this work, the Al/GO/Si/Al RRAM device was fabricated with solution-processed graphene oxide (GO) thin film at low temperature (50 □). A superior electrical performance and stable operation of the device has been achieved showing typical bipolar resistive switching characteristics with operation voltage lower than 3 V, retention property sustained over 104 s and endurance over 102 cycles. The results suggest that the solution-processed GO thin films exhibit great potential for use in the flexible device.

This study investigates the acoustic properties of micro-perforated panel (MPP) as an alternative to passive noise control. In order to obtain high sound absorption over broad frequency band, the analysis of sound absorption performance of MPP sound absorber should be conducted based on 3 major design parameters, such as perforation diameter, d, air cavity depth, D, and distance between perforations, b, of MPP. Next, the optimization of sound absorption coefficient for MPP sound absorber need to be done by using the Particle Swarm Optimization (PSO) algorithm and the optimum parameters of a single layer MPP sound absorber should be obtained for achieving higher sound absorption which the sound absorption coefficient, α + 0.5 with a wider frequency band. The PSO is used in order to optimize the panel construction to provide maximum sound absorption coefficient in a determined wide band frequency range. Experiments are carried out at normal sound incidence and plane waves. A good agreement is achieved between the theory and the experiments.

We demonstrated a waveguide crossing for submicron silicon waveguides with average insertion loss of 0.18±0.03 dB and crosstalk of -41±2 dB, uniform across an 8-inch wafer. The device was fabricated in a CMOS-compatible process using 248 nm lithography, with only one patterning step.

The effect of nanosized FeF2 (∼120 nm) addition on the critical current density, J c, of YBa2Cu3O7−δ was studied. YBa2Cu3O7−δ superconductor was prepared by the solid-state reaction method with addition of 0 to 0.10 wt% FeF2 additions. The magnetization critical current density, J cm (at 77 K), was estimated from the extended Bean model by using vibrating sample magnetometer (VSM) measurements. The transport critical current density, J ct, was measured using the four-point probe method with the 1 µV/cm criterion. The onset transition temperature, $T_{\mathrm{c}\mbox{-}\mathrm{onset}}$ showed a maximal value at 92 K for 0 to 0.03 wt% additions. J c increased with FeF2 addition up to 0.03 wt%. Addition of FeF2 of more than 0.03 wt% suppressed $T_{\mathrm{c}\mbox{-}\mathrm{onset}}$ and J c. The inter-grain current density was enhanced by two orders of magnitude on 0.03 wt% FeF2 addition. In addition to the condensation energy associated with their core, the full vortex magnetic energy by addition of nanosized FeF2 enhanced J c in the system.

Laser scattering method as a non-contact method provides an opportunity to real-time monitor the evolution of periodic nanostructures during fabrication, e.g. when the surface is irradiated with a focused ion beam. Using the method, the diffraction angle needs calibrating according to the grating equation. In this paper, we used scalar analysis to demonstrate the use of a dual-period structure for formation of dual spectral peaks at the 1st diffraction order. We then made use of numerical study based on rigorous coupled-wave analysis to optimize these Al-grating structures in terms of depth. It is found that dual-peak wavelengths can be selected by using different angles of incidence and low-loss reflection is obtained using an optimized structure. It is further proposed that these wavelengths can be used to determine the diffraction angle during fabrication without the need for pre-calibration of an optical scattering system.

The aim of this study is to analysis the sound transmission loss (STL) for the laminated glass and Perspex. In this study, the STL of laminated glass and Perspex are determined using the two-load transfer function method (TFM) impedance tube measurement setup. There are 5 mm and 8 mm thickness of glass and Perspex were used. Glass and Perspex will be laminated into double and triple layer in order to investigate its STL due to interlayer effect. All the specimens are prepared into round shape with the diameter of 33 mm that fit with the inner diameter of impedance tube. From the measurement, it is concluded that the STL almost similar for the Perspex and glass without the layer lamination at the frequency range below 3500Hz. Number of interlayer for the glass or Perspex lamination plays the major role as main parameters that affect the overall STL.

Effect of low sliding speeds (0.01–1.0 m s−1) on wear behaviour of an AZ91D magnesium alloy was studied under dry sliding condition using a pin-on-disc configuration. The wear rates were measured under a constant load of 10 N but two different sliding distances (1 and 10 km). Analyses of the wear tracks, worn surfaces and wear debris were carried out using scanning electron microscope and X-ray diffractometer. Thermogravimetric analyses were conducted to study oxidation behaviour of the wear debris. The friction coefficient values were found to fluctuate with increase in sliding speed leading to the three different wear transitions. Abrasive wear occurred during sliding at 0.01 m s−1. Oxidational wear was predominant at 0.1 m s−1 sliding speed. High sliding speed, 1.0 m s−1, resulted in delamination wear. The wear rate was highest in abrasive wear and lowest in oxidational wear. Oxide particles of Mg–Al–O and MgO2 were mainly observed in the abrasive wear. The majority of oxidational wear debris were oxides of Mg and Al in the form of MgO and MgAl2O4. The largest amount of uncombined Mg was found in delamination wear debris.

A V-shaped nano-aperture flanked with surface corrugations at exit side for beam focusing is introduced in this paper. Our finite-difference time domain (FDTD) numerical algorithm results demonstrate that the V-shaped aperture with width at incident side d(2) as small as 10 nm and surrounded with 14 grooves with a constant depth of 80 nm can intensely excite a transmission and focusing the beam in far-field region. The beam propagating with 78.91 mu m focal length and similar to 4 mu m spot size can be obtained for the practical V-shaped nano-aperture which can be naturally formed during the FIB fine milling. Changing the groove number and aperture width at exit side d(1) has limited contribution on the transmission due to their nonlinear relations with the electric field intensity vertical bar E vertical bar.(2) The V-shaped nanostructures may be useful in nanophotonics devices.

Accurate end point detection of interface for multilayers using focused ion beam (FIB) is important in nanofabrication and IC modification. Real-time end point graph shows sample absorbed current as a function of sputtering time during FIB milling process. It is found that sample absorbed current increases linearly with ion beam current for the same material and changes when ion beam is milling through a different material. Investigation by atomic force microscope (AFM) and FIB cross-sectioning shows that accurate SiO 2 /Si interface occurs to where the maximum sample absorbed current occurs. Since sample absorbed current can be real-time monitored in focused ion beam machine, the paper provides a viable and simple method for accurately determining the interface during FIB milling process for widely used SiO 2 /Si system.

In this paper, we report the effects of polarization state of individual beams in ablation of surface relief gratings using a two-beam interferometric technique. We have carried out ablation experiments on (111) silicon to form surface relief gratings by interfering two femtosecond laser beams under different polarization combinations. Four combinations of polarization were studied, i.e., s-: s-polarization, s-: p-polarization, p-: p-polarization and circular-: circular-polarization (c-: c-polarization). A novel interferometer was used for the investigation. The grating depths, surface roughness and ablation thresholds have been shown to depend on the polarization state of the interfering beams.

Femtosecond-pulse laser pulses have been shown to hold great potential for high-precision micromachining. Much research has been done to characterize the laser parameters for predicting the feature size, and the most important of these is the number of pulses incident at each point of ablation. Theoretical modeling, so far, has been restricted to a single point where the number of pulses incident at each point of ablation depends on the pulse-repetition rate and the dwell time of the laser beam at that machining point. However, to make the theoretical model useful, a laser scanning system with the ability to fabricate complex microfeatures is considered in this work. In this case, the scanning resolution determines the number of pulses incident at each scanning point. This has been taken into account while presenting a theoretical and experimental analysis of the effect of the scanning resolution on the threshold fluence of the material. Results of ablation on a gold thin film were subjected to theoretical analysis to predict the feature size. In addition, the effect of the energy fluctuation of the laser on the feature size has been evaluated to predict the minimum achievable feature size for a gold thin film.

In this paper, integration of interference phenomenon into femtosecond laser micromachining was reported as the femtosecond laser pulses were reshaped spatially to perform ablation. The generation of circular interference pattern was demonstrated by overlapping infrared femtosecond laser pulses. The interference pattern was subsequently focused on a copper substrate to ablate microstructures of concentric circular rings. The present technique is expected to open up new applications in the areas of rapid fabrication of micro-Fresnel lenses, hybrid microlenses and lens arrays.

Voltammetric studies on C60 fullerene particles adhered to an electrode surface by solvent casting or mechanical transfer exhibit evidence of nucleation and growth controlled processes for the C600/– and C60–/2– solid state when the modified electrode is in contact with acetonitrile solutions containing NBu4+ electrolyte. Although peak potentials and peak separations are dependent on scan rate as well as the amount of deposit and temperature, potentials obtained using a zero-current extrapolation method are almost independent of all these parameters. These data enable reversible potentials of –816 and –1168 mV vs. Ag/Ag+ to be obtained in acetonitrile (0.1 M NBu4PF6) respectively for the processes: \({\rm C}_{{\rm 60}} \left( {{\rm solid}} \right) + {\rm NBu}_{\rm 4}^ + \left( {{\rm solution}} \right) + {\rm e}^ - {\rm }\buildrel {} \over \rightleftharpoons {\rm NBu}_{\rm 4} {\rm C}_{{\rm 60}} {\rm (solid)} \) and \( {\rm NBu}_{\rm 4} {\rm C}_{{\rm 60}} \left( {{\rm solid}} \right) + {\rm NBu}_{\rm 4}^{\rm + } \left( {{\rm solution}} \right){\rm + e}^{\rm - } \buildrel {} \over \rightleftharpoons \left( {{\rm NBu}_{\rm 4} } \right)_{\rm 2} {\rm C}_{{\rm 60}} \left( {{\rm solid}} \right) \) . Images obtained by scanning electron microscopy reveal that both the crystalline and particle size is enhanced by 60 s of reductive electrolysis, with the detected (NBu4)2C60 crystals being slightly larger than those of (NBu4)C60. After a short period of potential cycling or controlled potential electrolysis, it is concluded that the data obtained by either method of surface adherence are almost indistinguishable, as are their morphologies.

This article presents experimental results of precision machining of steel alloys with polycrystalline diamond tools. Ultrasonic vibration-assisted cutting was tried out for expanding the application of diamond tools for high-precision and high-quality machining of ferrous materials. The experimental results show that compared with conventional turning, the cutting performance, in terms of cutting force, surface finish, and tool life, was improved by applying ultrasonic vibration to the cutting tool. The cutting forces and tool wear measured in vibration cutting are much lower than those in conventional cutting. The tool wear mechanism was discussed on the basis of the observation of wear zone.

Femtosecond lasers have considerable advantages over conventional laser sources for microfabrication. Even features with sizes very much less than the focused beam spot size of the laser can be fabricated using these lasers. Considering the potential of the laser for microfabrication, a valuable technique has been developed for the fabrication of binary photomasks by using femtosecond laser ablation of thin films. This is a single-step process and is faster compared to the complex multi-step lithography process currently used for photomask fabrication. A dispersion compensated acousto-optic scanning system has been developed for scanning the beam to transfer the required pattern to the mask blank. The applicability of this technique for microfabrication has been proven conclusively by fabricating microfeatures with the photomask fabricated by this technique. This can be made industrially viable by incorporating femtosecond laser sources with high pulse repetition rates.

Photomasks are the backbone of microfabrication industries. Currently they are fabricated by a lithographic process, which is very expensive and time consuming since it is a multi-step process. These issues can be addressed by fabricating photomasks by direct femtosecond laser writing, which is a single-step process and comparatively cheaper and faster than lithography. In this paper we discuss our investigations on the effect of two types of laser writing techniques, namely front- and rear-side laser writing, with regard to the feature size and the edge quality of a feature. It is proved conclusively that for the patterning of masks, front-side laser writing is a better technique than rear-side laser writing with regard to smaller feature size and better edge quality. Moreover the energy required for front-side laser writing is considerably lower than that for rear-side laser writing.

Hydrogen-free amorphous carbon films were deposited at different deposition bais voltage on a single silicon wafer by a process known as Filtered Cathodic Vacuum Arc (FCVA). The influences of different deposition bias voltages on the microstructure and the properties of thin tetrahedral amorphous carbon (ta-C) films, such as surface roughness, film mass density and thickness, have been studied by means of the x-ray reflectivity technique (XRR) for the first time. The microstructure of these films deposited on silicon wafers was stimulated by a four-layer model consisting of a ta-C layer, a mixed ta-C:Si layer, Si-O layer and the silicon subtrate. The mixed ta-C:Si layer consisting of the mixture of ta-C and silicon simulates the carbon ion impinging / diffusion into the surface of the silicon substrate. The mass density and the roughness of the film are found to be dependent on the impinging ion bombardment energy. The mass density increases with increase in ion bombardment energy up to 100 eV. Beyond 100 eV, the mass density decreases with further increase in ion bombardment energy up to 100 eV. Beyond 100 EV, the mass density decreases with further increase in ion bombardment energy. The surface roughness decreases with increasing ion bambardment energy to a minimum value at 100 eV, after which it increases with further increase in ion bombardment energy. The thickness of the films obtained by XRR technique correlates well with the thickness measurement obtained by spectral reflectometry. The existence of the Si-O layer was verified by Auger depth profiling.

Unhydrogenated amorphous carbon films were deposited at different temperatures on a single silicon wafer by a process known as Filtered Cathodic Vacuum Arc. A transition from diamond-like properties to graphitic properties was observed at the substrate temperature of 200°C. This change of properties upon transition includes a change in compressive stress, frictional coefficient and density. The variation of results is consistent with the subplantation model, which emphasizes the role of carbon atoms trapped in the subsurface layers in the evolution of a dense sp 3 -rich phase at room temperature. At higher temperature (>200°C) diffusion of carbon atoms to the surface of the evolving film releases internal stress and leads to the formation of a graphitic sp 2 phase. Based on x-ray reflectivity measurements, it was found that a thin interlayer formed between the tetrahedral amorphous carbon film and the silicon substrate contributes greatly to the good fitting of the spectra. The thickness of this interlayer is independent of the temperature. The optical properties were found to undergo a more gradual transition with the deposition temperature.

In this paper, the stiffness loss of general composite laminates with transverse cracks under mixed-mode loading is analyzed. The effective stiffnesses of the laminates are assumed to be functions of the nonlinear internal state variables (ISVs), which are dependent on crack densities, ply constraints, and crack opening profiles. The ISV corresponding to Mode I cracking is obtained from a series of finite element analysis. The ISV corresponding to Mode III cracking can be related to the Mode I ISV by considering geometrical constraints arising from the layup, for a laminate under tensile loading. Theoretical predictions of stiffness loss of glass/epoxy and graphite/epoxy composite laminates with transverse cracks are compared with experimental data available from published sources, for crossply, angleply, and quasi-isotropic laminates. In addition, the model enables the contributions from respective modes to the overall stiffness reduction to be determined. Results of analyses have shown good and excellent agreement with published experimental data from other researchers.

In general, the load-bearing capacity of laminated composites can remain significant despite the presence of damage in the constituent plies. The types of damage frequently encountered in laminated composites include delamination, matrix cracking, fibre breakage and fibre-matrix debonding. It is useful, for the purpose of damage tolerance analysis, to be able to predict and correlate the extent and severity of damage with changes in the mechanical properties of the composite laminate. This paper describes a series of finite element parametric studies performed for cross-ply laminates containing uniformly distributed transverse matrix cracks. Results of the analysis are used in a theory for damaged composite laminates to predict changes in laminate stiffness.

The marking of integrated circuit (IC) packages with neodymium-doped yttrium aluminium garnet (Nd: YAG) lasers has become a widely accepted technique in the microelectronics industry. This paper presents a literature survey and discussion of the various methods and mechanisms of Nd: YAG laser marking of plastic and ceramic IC packages. The effects of the material properties (e.g. the absorptivity and the melting point) and the marking parameters (e.g. power density, the focal position and the marking speed) on the mark legibility characteristics (e.g. the mark contrast and the mark width) are reviewed. Economic advantages and technological limitations of thr marking of IC packages with Nd: YAG lasers are discussed also.

Laser machining of submicron grooves on silicon wafer by 400 nm femtosecond laser is studied. A chirped pulse amplification based Ti:sapphire system that produces pulse with a pulse duration of 150 fs at a repetition rate of 1 kHz is used. Focusing lens with numerical aperture of 0.36 focuses the laser beam into a 3 μm laser spot (by calculation). The sample was translated at a linear speed of 400 μm/s during machining. 500 nm wide 100 nm deep groove was obtained on the wafer when the sample was irradiated by pulses with energy of ∼50 nJ/pulse and 800 nm wide 650 nm deep groove was obtained by pulse with energy of ∼100 nJ/pulse.

A p-polarized femtosecond laser beam was used to irradiate a UV grade fused silica to create microchannels, which are useful for producing optical gratings or micro fluidics devices. The laser irradiated surface was characterized using optical microscope, stylus profiler, SEM, XRD and TEM. A special technique was used to protect the laser irradiated surfaces in preparing cross-sectional TEM samples. The XRD spectra and TEM observation reveal that structure of the fused silica remain amorphous after the femtosecond laser irradiation.

Ultrashort pulsed laser material processing is a new micromachining method that is gaining interest. Its capability of submicrometer machining has been proved. To obtain high speed and highly flexible beam steering, a two-axis acousto-optic deflector is employed. However, dispersion associated with acoustic-optic interaction will cause serious spatial deformation on the writing spot. The compensation for dispersion is proposed and studied. Experiments show promising results. An additional advantage of the proposed compensation method is that it can also precisely control the pulse number, and, hence improve the quality of ablation.

An approximate expression is developed for the stress-intensity factor due to concentrated point loads applied to the surfaces of a complete circumferential interior surface crack in a hollow circular cylinder. This expression is derived from existing results for a point load on an embedded penny-shaped crack and a concentrated "ring" load on a complete circumferential interior surface crack in a hollow cylinder. Results for a particular loading case were obtained using the approximate solution and comparing with three-dimensional results obtained using boundary integral equation techniques. Since the agreement was good, it is concluded that the approximate expression provides a sufficiently accurate means of estimating K for an arbitrary loading on an interior complete circumferential surface crack. Results for bending of a cracked cylinder are then presented as an example of the use of the approximate K solution. Convenient curve fits of relevant results are included in the Appendix.

Composite materials and some exotic alloys have been used in the fabrication of both structural and non-structural members of the air-frames and engines of aircrafts. Different machining processes, such as the use of traditional solid tools with modified cutters, ultrasonic cutting and drilling, water-jet cutting, abrasive water-jet cutting, electron beam welding, and various laser processes have been applied successfully to the processing of these materials. In this paper, the physical mechanisms, the advantages as well as the limitations, and examples of application of the laser processes that are used to machine aircraft components are reviewed.

In our earlier work, a multipoint diffraction strain sensor using a microlens array was developed for measurement of whole-field strains. The method is extended to a system with variable sensitivity and measurement range. In the present system, two collimated laser beams, 3 mm in diameter, symmetrically strike the grating attached to the specimen surface at prescribed angles. The diffracted wavefronts, magnified by a microscope objective, are sampled by a lenslet array with each microlens acting as an individual strain sensor. In-plane strain components over the full field can be measured by what is to our knowledge a new sensor with variable sensitivity by changing the distance from the microscope objective to the microlens array. Both a theoretical explanation and experimental verification are provided.

We demonstrate a widely tunable cascaded all-fiber Raman laser in a combined linear and Sagnac-loop configuration which provides an output power of several hundred milliwatts and a tuning range of 120 nm without employing any bulk-optical devices

In this paper the impact of the ESL (Etch Stop layer) nitride on the device performance especially the threshold voltage (Vt) has been studied. From SIMS analysis, it is found that different nitride gives different H concentration, [H] in the Gate oxide area, the higher [H] in the nitride film, the higher H in the Gate Oxide area and the lower the threshold voltage. It is also found that using TiSi instead of CoSi can help to stop the H from diffusing into Gate Oxide/channel area, resulting in a smaller threshold voltage drift for the device employed TiSi. Study to control the [H] in the nitride film is also carried out. In this paper, RBS, HFS and FTIR are used to analyze the composition changes of the SiN films prepared using Plasma enhanced Chemical Vapor deposition (PECVD), Rapid Thermal Chemical Vapor Deposition (RTCVD) with different process parameters. Gas flow ratio, RF power and temperature are found to be the key factors that affect the composition and the H concentration in the film. It is found that the nearer the SiN composition to stoichiometric Si3N4, the lower the [H] in SiN film because there is no excess silicon or nitrogen to be bonded with H. However the lowest [H] in the SiN film is limited by temperature. The higher the process temperature the lower the [H] can be obtained in the SiN film and the nearer the composition to stoichiometric Si3N4.

This paper has two parts. The first compares the measured burned gas temperature using Coherent Anti-Stokes Raman Scattering (CARS) with the predictions of a multiple zone computer simulation of combustion. The second part describes a system that is capable of determining the heat flux into the combustion chamber by means of measuring the chamber surface temperature. It is shown that the multi-zone computer simulation can accurately predict the burned gas temperature once the fuel burn rate has been analyzed and the model tuned correctly. The effect of different fuels (methane and iso-octane) on the burned gas temperature is reported. A high burn rate or more advanced ignition timing gave a lower burned gas temperature towards the end of the engine cycle. The surface heat flux was deduced from measurements of the surface temperature by using a finite difference method. From the experimental results, it was found that there are significant cycle-by-cycle variations in the surface heat flux in both the magnitude and phasing. Therefore, a cycle averaged heat flux has significantly different characteristics from a single cycle. These cycle-by-cycle variations in the heat flux were associated with corresponding variations of the propagation of the flame through the combustion chamber. This in turn is due to the variations in combustion. The effects of ignition timing and air-fuel mixture on the surface heat flux are reported. Comparisons between experimental surface heat flux measurements and established heat transfer models show large discrepancies. Copyright © 2000 Society of Automotive Engineers, Inc.

Inhomogeneities in waveguide dimensions are a serious problem for guided‐wave frequency conversion devices. We discuss waveguide designs that make the phase matching ‘‘noncritical’’ with respect to small changes in dimensions. Application of noncritical phase matching results in larger fabrication tolerances, facilitating the practical realization of nonlinear devices with long interaction lengths. We experimentally demonstrate the existence of a noncritical thickness in a lithium niobate waveguide, and analyze the dimensional tolerances for second‐harmonic generation in a polymer waveguide.

We report the first observation of voids in sub-quarter micron Ti-salicided BF2-dopedpolycrystalline silicon (polySi) lines. Some of the voids, with sizes ranging from 10 to 100nm, can be clearly seen on the surface of the TiSi2 film whereas others are situated below the TiSi2 surface. The void density and size increase with decreasing polySi line-width, especially for line-widths < 0.24 µm. The voiding phenomenon was also observed to be moresevere for TiSi2 fabricated with enhanced salicidation techniques such as pre-amorphization-implant(PAl) and implant-through-metal (ITM) as compared to the conventional salicidationmethod without amorphization. The origin of the voids is found to coincide with the fluorinepeak at the TiSi2/polySi interface in the SIMS depth-concentration profiles.

Important active technologies, modulators, photodetectors, and thermooptics for low-energy silicon optical interconnects are discussed. High-speed performance up to 40 Gb/s is reported for the silicon modulators and germanium photodetectors, and approaches for further improvement in speed and efficiency are presented. Low-voltage avalanche multiplication is demonstrated, giving a gain-bandwidth product of 75 GHz, while the combined effects of multiplication gain and the Franz-Keldysh effect enable a 5-μm-long germanium photodetector to achieve responsivity in the L-band that is comparable to that in the C-band. With trench-based thermal isolation, a low switching power of 0.4 mW is achieved for a thermooptic switch.

We report quasi‐phase‐matched difference‐frequency generation of 2.1 μm radiation at room temperature using the d33 nonlinear coefficient in a periodically poled lithium niobate channel waveguide. A tunable Ti:Al2O3 laser (λ≊0.8 μm) and a Nd:YAG laser (λ=1.32 μm) were the pump and signal sources, respectively. With 160 mW of 0.81 μm and 1 mW of 1.32 μm radiation coupled into the waveguide, 1.8 μW of 2.1 μm radiation was generated, tunable over a 6 nm bandwidth. We also show that the annealed proton exchange process can change the shape of ferroelectric domains in lithium niobate.

Localized Ga implantation by means of a focused ion beam and subsequent deep reactive ion etching is used to fabricate microstructures or nanostructures in Si. It is found that the area irradiated with the focused ion beam acts as an etch stop in reactive ion etching. The etch rate ratio between the unimplanted and Ga-implanted area increases to 2.56 with an increasing Ga ion dose up to 1.59 × 1016 ions cm−2. However, the etch rate ratio decreases with further increase in ion dose and the surface of the etched Si microstructures is concave due to the effect of ion sputtering during focused ion irradiation. This technique is promising for the fabrication of 3D nanostructures in Si.

One challenge in fabricating submicron ridge waveguide photonic devices is the formation of metal contacts and passivation. In this article, the authors report a self-aligned metal-contact and passivation technique suitable for submicron to nanoscale ridge waveguide device fabrication. The technique uses two different dielectric materials, e.g., SiO2 and Si3N4, with a different wet-etching selectivity. The first dielectric material (SiO2) acts as the etching mask and the second dielectric material (Si3N4) with a much lower etching rate acts as the passivation film. An undercut is formed in the semiconductor below the SiO2 mask by a wet-etching process. The semiconductor surface on top of the ridge waveguide will be fully exposed to metal contact by the lift-off process. A 0.7-μm-wide InGaAsP∕InP ridge waveguide laser was fabricated using the technique proposed. Mode simulation showed that the 0.7-μm-wide and 1.2-μm-deep ridge waveguide in the InGaAsP∕InP laser structure has good optical field confinement....

An optical probe with a single aperture flanked by depth-tuned grooves is presented. It is employed as an example to investigate propagation properties of the plasmonic nanostructures with a nonparaxial Gaussian beam illumination. The propagation through the subwavelength aperture is the process that a near-field diffraction of the Gaussian beam interferes with the surface plasmon polaritons (SPP) wave induced wavelets on surface of the grooves. An enhanced optical transmission at the exit side of a subwavelength aperture and a degraded reflection at top side of the compound dielectric/metal nanostructure (air/glass/C/Ag/air) of the probe can be generated with this illumination. Characteristics of the Gaussian beam illumination have been studied numerically via analysis of the transmission and reflection issues. In contrast, the results for plane wave illumination were given as well. Two-dimensional (2D) finite-difference time-domain (FDTD) algorithm is employed for the 2D simulation.

We discuss a novel whole-field optical strain sensor termed the moire interferometric strain sensor (MISS) for simultaneous measuring of multipoint strains and whole-field contours of in-plane displacement. A high-frequency grating, attached to the surface of a specimen, is used as the displacement and strain-sensing unit. When illuminated by two collimated beams at a prescribed angle, the interference of the diffracted beams gives the whole-field deformation contours. If, on the other hand, each of the individual beams is separately imaged using a multilens CCD sensor similar to a wavefront sensor, the separation between the spot centroids for each microlens is directly proportional to the normal or shear strain component at the corresponding position on the specimen. Applications are demonstrated for uniform rotation and simulated in-plane strains.

Design of an enhanced surface plasmon polaritons (SPPs) based nanostructure for the purpose of beam shaping is discussed. An indentation with depth-tuned grooves is presented to realize the beam shaping and extraordinary transmission. The nanostructure is directly fabricated using focused ion beam (FIB) milling on an Ag thin film coated on quartz with a thickness of 200 nm. A large measurement error is found during geometrical characterization of the nanostructures by use of an atomic force microscope (AFM) working in tapping mode. Apex wearing and 34 deg full cone angle of the probe generate the measurement errors during the characterization of nanostructures with a feature size of 200 nm and below. To solve this problem, an FIB trimmed AFM probe is employed in the geometrical characterization. The results show that the error is improved greatly using the trimmed probe. The desired excitation of the SPPs is derived using an optical fiber coupled CCD spectrometer after the modified geometrical characterization. The designed structure can be used as an optical probe for future inspection and detection use. (c) 2006 Society of Photo-Optical Instrumentation Engineers.

Photomasks are currently fabricated using the lithographic process, which is complex and time consuming because of several steps involved in the fabrication process. In order to address this a simple technique is proposed in this article which is a single-step process. The required pattern is transferred to mask blank by direct writing with ultrashort laser pulses without the aid of photoresist. A nonmechanical scanning system immune to effects of vibration has been developed in order to scan the laser beam with high positional accuracy and scan speed. It is a cost effective technique when compared with the lithographic process and is capable of fabricating photomasks with submicron features.

Laser writing using conventional lasers has found widespread application in the fabrication of electronic components and the repair of integrated circuits. However, due to large thermal damage associated with the laser ablation process, these lasers are not suitable for microelectronic components with submicron feature size. To address these issues, a novel system is introduced for laser direct writing using femtosecond lasers. Here, an acousto-optic deflector-based scanning system has been developed for steering the femtosecond laser beam with high positional accuracy, resolution, and scan speed. The capability of the system to machine complex features with submicron line widths has been proved. This system has profound potential application in the electronic and microfabrication industry.