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The paper is aimed to the methodology for estimation of service life of mechanical engineering components in the case of elastic-plastic contact of surfaces. Well-known calculation methods depending on physics, theory of probability, the analysis of friction pair’ shape and fit include a number of parameters that are difficult or even impossible to be technologically controlled in the manufacturing of mechanical engineering components. The new approach for wear rate estimation using surface texture parameters as well as physical-mechanical properties and geometric parameters of components is proposed. The theoretical part of the calculations is based on the 3D surface texture principles, the basics of material fatigue theory, the theory of elasticity and the contact mechanics of surfaces. It is possible to calculate the service time of the machine, but the process of running-in of the components is relatively short (less than 5%), therefore, the service time is mainly determined by a normal operating period, which also was used to evaluate this period. The calculated input parameters are technologically and metrologically available and new method for calculating the service time can be used in the design process of the equipment. The results of approbation of the method for estimation service time of mechanical engineering, which prove the applicability of mentioned method, are offered as well.

In this work, ray tracing is used to investigate the effects of pyramid texture angle towards light absorption and photocurrent in 250 μm-thick crystalline silicon (c-Si) absorber. Upright pyramids with texture angles of 10-50o are investigated. Planar c-Si absorber is used as a reference. When the pyramid angle increases, the broadband reflection reduces due to enhanced light scattering which leads to improved light absorption. At angle of 50o, the weighted average reflection (WAR) reduces to 14.7% and broadband light absorption increases. The optical path length enhancement increases to 12 at wavelength of 1100 nm. The reflection and photogenerated current density (Jg) exhibit an inverse relationship with increasing zenith angle. With increasing zenith angle, the reflection from the c-Si absorber increases and this results in lower light absorption and Jg. In the passivated emitter rear cell (PERC) solar cell, the planar solar cell exhibits short-circuit current density (Jsc) of 26 mA/cm2 with conversion efficiency of 13.6%. When both the pyramids and the silicon nitride (SiNx) anti-reflective coating (ARC) are incorporated on the solar cell, the Jsc increases to 39 mA/cm2 and conversion efficiency increases to 20.5%. This is attributed to the enhanced light-trapping and light-coupling effects in the device.

4H silicon carbide (SiC) based pin photodiodes with a sensitivity in the vacuum ultraviolet spectrum (VUV) demand newly developed emitter doping profiles. This work features the first ever reported 4H-SiC pin photodiodes with an implanted p-emitter and a noticeable sensitivity at a wavelength of 200 nm. As a first step, Aluminum doping profiles produced by low energy ion implantation in 4H-SiC were characterized by secondary-ion mass spectrometry (SIMS). Photodiodes using these shallow emitters are compared to one with a deep p-emitter doping profile employing IV characteristics and the spectral response. SIMS results demonstrate the possibility of shallow Alimplantation profiles using low implantation energies with all emitter profiles featuring characteristic I-V results. For some shallow doping profiles, a meassurable signal at the upper limit of the VUV spectrum could be demonstrated, paving the way towards 4H-SiC pin photodiodes with sensitivities for wavelengths below 200 nm.

Compressively strained SiGe is an interesting channel material for sub 45 nm p-MOSFETs because of its superior hole mobility (up to 10x over bulk Si channels) and compatibility with current Si manufacturing technologies. In this work, the impact of heterostructure composition and SiGe channel thickness on the electrical characteristics of p-MOSFET are studied. Using strained Si0.8Ge0.2 p-MOSFET, the thickness was altered to a few thicknesses of 3 nm, 5 nm, 7 nm, and 9 nm respectively. The optimal thickness was then used for Ge compositions (x = 0.2). The project was realized utilizing computer-aided Silvaco TCAD tools, with ATHENA tools creating the p-MOSFET structure and ATLAS tools doing the device simulation. The strained-Si1-xGex p-MOSFET and the Si p-MOSFET were compared in terms of their performances. The ID-VG and ID-VD characteristics, as well as the threshold voltage, VTH extraction, were the focus of the device simulation. The 7 nm thickness strained-Si0.8Ge0.2 p-MOSFET exhibited lower VTH than other SiGe thicknesses and the Si p-MOSFET which is VTH = 0.074 V. The lower threshold voltage of the strained-Si0.8Ge0.2 with 7 nm thickness indicating that the strained-Si1-xGex contributed to the decreased power consumption. In addition, the extracted IDsat for the strained-Si0.8Ge0.2 p-MOSFET with 7nm thickness provided higher IDsat compared to conventional Si p-MOSFET and other SiGe thicknesses devices. As compared to Si p-MOSFETs, the output characteristics of the strained-Si1-xGex demonstrated a drain current improvement by a factor of 1.01.

Gold nanoparticles (AuNPs) is known for its high surface area to volume ratio which acts as an excellent receptor when placed in between electrodes in sensors application. Microelectrodes which are bar and needle shape pointed ends with two arrangements; comb and castle wall configurations were designed to be used for fabrication of electrodes to observe the relation between geometry of electrodes and dielectrophoretic of AuNPs on p-gallium nitride (GaN) substrates. The dielectrophoretic behaviour and electrical properties were analysed before and after the drop cast of AuNPs using current-voltage (I-V) curve method with manual probing. Resistance values of each sample were calculated under reverse bias condition. The effect of design on the nanomanipulation of AuNPs will be discussed.

Semiconductor manufacturers and researchers have recently revealed that under specific bipolar gate switching conditions SiC MOSFETs exhibit parameter drift dynamics different from those typically observed in static qualification stress tests. In response to this finding, we present an approach for assessing the worst-case drift of data-sheet-relevant electrical parameters in a simple and transparent manner for a large variety of application profiles. We also introduce an empirical model that may explain the drift dynamics observed under gate switching stress; and discuss a recently developed interface characterization technique that has the potential to reveal the nature of point defects at the SiC/SiO2 interface presumably related to the gate switching instability in SiC MOSFETs.

In this study, ZnO nanowire field-effect transistor (FET) with an aluminium-doped ZnO (AZO) and an aluminium (Al) dual layer source and drain contact are fabricated and temperature dependent characteristics in the range of 200 – 300 K are analyzed through experimental measurements. The effect of temperature on threshold voltage, subthreshold slope, transconductance, and field effect mobility are analysed. The transfer curve exhibits a parallel shift toward a negative gate voltage direction with a negative shift of the threshold voltage, an increase in the subthreshold slope, and a field-effect mobility as the temperature rises. The electrical properties of the transistors demonstrate typical behaviour at various temperatures.

The SiC trench gate MOSFET with narrow cell pitch is demonstrated using a process in which the n+ source is self-aligned to the trench gate. A minimum cell pitch of 1.6 μm, which is difficult to achieve using the conventional device structure, is easily fabricated by applying a deep n+ source and a buried interlayer dielectric structure. The cell pitch reduction indicates a beneficial trend that contributes to a decrease in the specific on-resistance and an increase in the breakdown voltage. The process and structure are promising for further improving SiC power device characteristics.

To scale digital circuits, symmetric threshold voltages (Vth) for n-type transistors (NMOS) and p-type transistors (PMOS) are important. One step towards this in silicon carbide (SiC) is selecting a p-doped polysilicon (pPolySi). This implementation has been shown in this work with Vth being evaluated by five different methods. Furthermore, operating temperatures up to 500 °C and their impact on Vth were investigated. It has been successfully demonstrated that elevated temperature shifts Vth of both transistor types towards 0 V, whereas changing the gate electrode from n-doped PolySi (nPolySi) to pPolySi shifts Vth of both transistor types to more positive values. Both effects are complementary for the PMOS, reaching Vth below 4 V.

Lateral GaN devices, with a substantial critical breakdown field and increased mobility of two-dimensional electron gas (2DEG), are particularly promising for future power applications. Despite low power consumption by design, further improvements are required in numerous areas, including reliability concerns and switching loss, usually contributing to significant power loss. The research objective concerns the impact of different notch structures on the transfer characteristics of GaN-based high-electron-mobility transistor (HEMT) devices. Thirteen simulated models were produced using COMSOL Multiphysics, incorporating the electrical, structural, and piezoelectric effects of the device. From the results, notch-structure devices demonstrated better electrical characteristics than devices using conventional architecture, particularly a model with a double-notch design. Higher transconductance and maximum drain current were among the improvements, benefiting from the notch structure at the barrier layer.

In line with the recent environmental concerns due to waste, researchers focus has been shifted to finding ways of recycling the waste in a most sustainable way. Accumulation of plastic waste, and rubber tyres in the environment is a concern and a threat to the environment. The current waste management has raised public awareness to look for new technologies for handling waste and an alternative to the current disposal technique. Some of the challenges encountered with the current waste management such as recycling, includes contamination of recycling streams, inability to meet recycling demand and the quality of the recycled plastics. One of the disadvantages of recycling is that it produces wastewater and air pollutants. Since recycling degrades the plastic integrity, most recyclable plastic waste is only suitable after one round of recycling, which ultimately leaves most recyclable plastic in the landfills, environment, and oceans. In addition to landfilling (waste management) and waste disposal, waste tires are also a worldwide problem. The current waste management method for waste tires is through incineration, whereby waste tires disposed and piled up in landfills, are treated through incineration. However, this process was found to be releasing enormous emissions, such as hydrocarbons and halogen-chlorinated compounds (chlorinated methanes, dioxins, and polychlorinated biphenyl (PCBs)). This also produces the pyrolytic oils that contains heavy metals and toxic chemicals, which have a potential of causing severe health effects. Moreover, exhausts from incineration of waste tires are far more mutagenic compared to coal-fires plants emissions . The study investigated the potential of modifying the bitumen binder with plastic (Polyethylene Terephthalate) and tyre wastes. In bitumen-rubber tyre modified binder, increasing the rubber tyre percentage above 5% in the binder, resulted in low ductility, due to the elasticity property of rubber, for both 5.5% and 6% bitumen. For the Bitumen-plastic modified binder, the softening point and ductility had a direct proportionality relationship. As the plastic percentage in the total weight of the binder increased, so did the ductility and the softening point, due to the plasticity property of the plastic that enabled the mixture to be homogenous.

The effect of the termination structure on the unclamped inductive switching (UIS) failure is analyzed for two kinds of SiC MOSFET, where S-MOS and G-MOS termination structure are adopted. The MOSFETs are named as S-MOS and G-MOS according to the buses connecting with different electrodes in the termination region. The experimental results indicate that the avalanche energy G-MOS can withstand is 1.15 times larger than that of S-MOS. To understand what are the factors that lead to different UIS capabilities, further static measurements and hotpot mapping after UIS test are done, and technology computer aided design (TCAD) simulation also is done to further confirm the principle.

A simple tapered multimode fiber (MMF) optic sensor is proposed and demonstrated as a refractometer for liquid samples application. The working mechanism of such device is based on the intensity modulated transmission of the tapered fiber when it is immersed in solutions with increasing refractive index. The tapered fiber is fabricated using heat-pulling method to achieve a waist diameter of 40, 50 and 75μm over the length of 18 mm. The performance of the tapered fiber with different waist has been evaluated on samples of ethylene glycol solution and glycerol. The obtained results show good correlation with the data provided by a commercial refractometer. The main advantages of this sensor are its enablement of miniaturization and simplification, ease to fabricate and handle while providing high accuracy measurement.

In this paper, the impact of the anode contact in SBDs, PiN, JBS and MPS diodes is analyzed through TCAD simulations. The focus of the investigation is the correct simulation of the Schottky barrier height on the different areas of the device to correctly simulate a JBS or MPS structure. It is found that the splitting of the anode contact and an accurate selection of the Schottky barrier height on pzone is necessary to allow the onset of the bipolar conduction in MPS devices. In this way, it is possible to correctly analyze the behavior of an MPS diode, including the snapback phenomenon.

Different material thickness with medium and high dielectric constant can impact the performance and reliability of high electron mobility transistor device. With varying the thickness of the passivation layer, the effect of it towards the device performance is still unclear. Two different insulator layers with a medium dielectric and a high dielectric constant namely Aluminium Nitride and Hafnium Oxide are used as passivation layer in AlGaN/GaN HEMT. Both material performance was simulated via COMSOL software by varying the thickness and the drain current output were compared. The passivation layer thickness of 10nm at Vds=6 V and Vgs=5 V, HfO2 outperforms AlN with the output drain current of 39 mA compared to 35 mA respectively. It was observed that HfO2 can attain higher threshold voltage, Vth as compared to the AlN because of the influence of its material properties that shows a direct proportional relationship between Vth and dielectric constant. Using high dielectric constant material like HfO2, we observe the ON-voltage gradually decreases as the thickness of the passivation layer increased. Out of all the thickness simulated for HfO2 and AlN, 10nm produced the highest drain current output instead of layer thickness of 20nm.

This work aims to optimize Plasma-Enhanced Chemical Vapour Deposition (PECVD) amorphous hydrogenated silicon carbide (a-SiC:H) as a conformal passivation layer for invasive microelectrode array (MEA) neural interface applications. By carefully tuning the PECVD deposition parameters, the composition, structure, electrical, and mechanical properties of the films can be optimized for high resistivity, low stress, and great resistance to chemical attack. This optimization will eventually allow a-SiC:H to be used as an ideal insulation, passivation and protection layer for thin and biocompatible all-SiC neural interfaces.

In this study, ferrous foundry slag was used as a precursor for the synthesis of a geopolymer. The effect of NaOH concentration, liquid solid ratio (L/S), and curing temperature on the unconfined compressive strength (UCS) of the synthesized geopolymer was investigated. The optimum concentration was found to be 15 M as it yielded a geopolymer brick with the highest UCS of 8.2 MPa. It was observed that as the concentration of NaOH increases the dissolution of alumina, calcium and silica increases resulting in higher UCS. The SEM results showed zeolite formation in large quantities at 15 M which shows that the geopolymerization reaction was near completion and the calcium, alumina and silicates dissolved in large quantities leading to increased gelling of C-S-H and C-A-H over time filling more pores inside the geopolymer brick. The liquid to the solid ratio that gave the highest UCS of 8.2 MPa was 0.15. The optimum temperature was found to be 80 °C. This increased temperature favoured the dissolution of reactive species and contributed to higher UCS. The results reveal that ferrous foundry sand geopolymers have the potential to be used as a building and construction material.

The technology of the 4th industrial revolution is providing opportunities to improve productivity in various fields including the construction industry. The level of activation of domestic smart construction technology is on the rise, and especially the technology linking 3D scanning and BIM improves the efficiency of management in the construction and maintenance stages. In this study, we are to increase the timeliness of quality inspection by applying 3D scanning technology to frame work with high dependence on manpower during construction work. In this study used case of applying technology. The precision of rebar construction by converting the subject of the study into data that can be analyzed through a three-step 3D scanning process and comparing it with a 3D BIM model based on design drawings was identified by case study. The result of the study showed that it was possible to compare the rebar spacing in the design drawing and the rebar spacing of the actual rebar. When 3D scanning technology was applied based on the research results, it was found that it is a highly efficient method compared to the existing method in the operation of the work type. Therefore, it is thought that it will be possible to contribute to the improvement of the competitiveness of the construction industry by securing examples of applying the 4th industrial revolution technology to various types of work and using it for future research.

The research investigated the chemical, mechanical and durability of composites developed from aluminum slag. Aluminum slag is a hazardous residue product of secondary Aluminum smelting. The objective of this research was to study the chemical and geotechnical properties of Al slag. To investigate the stabilization of Al slag with fly ash and GBFS binder to enhance the pozzolanic reaction. Lastly, to study the properties of developed composites and recommend the application. Aluminum slag can be categorized as black or white, with the black dross (slag) having low metal concentration and a granular-like appearance comparable to sand. White dross (slag) has a high metal concentration and contains small quantities of oxides and salts, forming huge blocks. Aluminum slag is a by-product of the foundry industry that is deposited in landfills, causing pollution such as soil, air, and groundwater contamination, as well as affecting human health. Aluminum slag recycling has become more popular in recent years, and it can now be used to make concrete and bricks instead of cement. When compared to properties obtained from composites produced from cement, Aluminum slag improves several properties of the material in this study. Properties such as compressive strength, workability, and durability of the material are found to be improved. At 40% binder and cured at 80°C, the mortar sample made from Al slag, GBFS binder, and fly ash had the highest unconfined compressive strength (UCS) of 24 MPa. The optimum number of days for curing was found to be 14 days. Based on the overall research, it can be concluded that Aluminum slag produced from the foundry industries can be stabilized with fly ash and GBFS binder to produce bricks and concrete

Metal organic chemical vapor deposition (MOCVD) was used to grow AlGaN/GaN HEMT on a sapphire substrate with a 3.0 nm GaN cap and a sample without a GaN cap. High resolution X-ray diffraction (HRXRD) was utilized to investigate the structural characteristics of the materials. The relationship between the electrical properties and two-dimensional electron gas (2DEG) I-V and Hall Effect measurement. The I-V measurement was used to investigate the resistance properties of AlGaN/GaN heterostructures. Hall Effect measurement was used to quantify electron mobility and sheet carrier concentration in both samples. The sample with a 3.0 nm GaN cap exhibited excellent electrical properties with 436.8 Ω/sq sheet resistivity and possessed a high value of sheet carrier concentration 3.46E+14 per cm2.

This article's purpose was to investigate the mechanical properties and morphological characteristics of gypsum boards. At dosages of 50:100, 75:75, and 100:50 by mass, gypsum plaster (GP) Type 1 was substituted with coconut fiber (CF) and water hyacinth fiber (WHF). While the mechanical qualities of the gypsum board were standard on the TIS 219-2552, scanning electron microscopy (SEM) was employed to notice their morphological characteristics. The ASTM C518 standard was used to measure the thermal conductivity (k). Referring to test results, the morphological characteristics of the GP incorporating CF and WHF showed rather roughness, clearly separated both fibers from the plaster surface. Gypsum board voids were reduced compared to WHF. As the void size increased, the thermal conductivity of gypsum boards combined with CF and WHF tended to decrease. Eventually, the bending forces (FL) and water absorption (AW) of the gypsum board with CF mixed WHF were found to be deficient for compliancy with the TIS 219-2552 standard.

A systematic experimental study is conducted on floating field rings (FFR) incorporated into 4H-SiC junction barrier Schottky (JBS) diodes across four voltage ratings 650, 1200, 1700 and 3300V, in pursuit of highly efficient FFR designs. 30 designs of FFR in 3 categories are studied for each voltage rating, and the measured breakdown voltage (Vbr) of JBS divided by ring system width (W) is taken as the figure of merit (FOM) of each design. The influence of ring spacing, ring width and number of rings on Vbr is studied in detail. It is found that the initial ring spacing (S1) is critical in determining the highest Vbr achievable by a certain design, and its optimum value increases as voltage rating increases. TCAD simulation verifies the importance of S1. For designs with a small ring system width, subsequent ring spacing can also become important. Ring width does not have a definitive effect, and Vbr saturates beyond a certain ring number. The design with the highest Vbr may not render the highest FOM. Even style designs with appropriate ring spacings can be advantageous likely due to less susceptibility to variation of field oxide charge, and more tolerance to fabrication error, as well as ease of design.

This study examines the influence of tool eccentricity pin positioning on AA6061 aluminium alloy friction stir welds. A laser scanning confocal microscope and optical microscope was used to analyze the surface roughness and the cross-sectional microstructure of the samples. Surface roughness analysis reveal the thread-to-flat (T2F) samples show rougher surface with increasing rotational speed up to 1400 rpm. On the other hand, the surface appearance of flat-to-thread (F2T) samples show minimal change. Cross-sectional microstructural observations show that the stir zone area of both groups increases with increasing rotational speed. However, the periodic bands in T2F and F2T samples increases in the upper region and lower region of the stir zone, respectively.

Three-dimensional finite element modeling (FEM) has been carried out using QForm software on the hot forging operation of the upper ball joint, involving the process of roughing and finishing. The material used is SNCM8 commercial alloy steel. This paper aims to optimize the initial billet size to achieve a final forged product without any defects. To accomplish this task, it was necessary to determine the initial optimum billet size by calculating the mass ratio. It is more practical to reduce the length of the initial billet and keep the diameter constant. The initial billet size was obtained by FE simulation by varying the five cases of mass ratio. The minimum dimension of the initial billet, which filled the die cavity without defects, was selected for the tryout experiments. The experimental results supported the FEM results and indicated that the optimum size was ∅48x152.88 mm, which may reduce material waste by 17.65%. Additionally, the forging load during the forging process was investigated. The actual forging load was slightly higher than the experimental one. The forging load showed a maximum error about 10.13%. Finite element simulation by QForm V10.1.6. software is recommended as an efficient tool for predicting the hot deformation behavior of the material during several stages of hot forging, which can save material costs and the cost of trials, leading to enhancements in the manufacturing process.

Nanotechnology research has lacked to provide new studies on nanofibers using the electrospinning method, the reasons are attributed that all parameters have been covered by previous studies. Believing that science is in a state of constant renewal leads to the possibility to study a parameter that has not been studied before, which affects the morphology of nanofibers. One of the disadvantages of nanofibers manufacturing is the formation of beads, and controlling the parameter helps reduce these beads. Field emission scanning electron microscope (FESEM) images reveal the formation of nanofibers and surface topography observations by atom force microscopy (AFM) indicates that the roughness is improved by changing the distance between rods of the collector. The rods function as a collector for nanofibers, changing this parameter improves the morphology and diameter of the nanofibers.

In this work, polystyrene/aluminium (PS/Al) nanocomposites were fabricated based on the various concentrations (0, 1, 5, 10, and 15 mg) of Al nanoparticles using the casting method. The resulting polymer/metal nanocomposites have good optical properties. The optical features such as transmittance and absorbance of the as-fabricated nanocomposites were investigated using the UV-Vis spectrophotometer. The effect of constriction of Al nanoparticles was noticed clearly on the transmittance and absorbance of PS/Al nanocomposites. The samples showed high absorption in the UVB range. Photoluminescence spectra (PL) revealed the UVB region of emission peak with the increasing concentration of Al NPs.

This research aims to identify the optimal condition of the zinc Zamak3 alloys' melting process using 2k full factorial design and its optimizer in Minitab 18 software. The evaluation results of the ANOVA test with a first-order model revealed that the change in both independent variables simultaneously resulted in a statistically significant alteration of the percentage of slag. The independent parameters also had an effect individually on the response. Additionally, the slag percentage reduction was increased significantly due to an elevation of the temperature. However, the change of flux type resulted in an overall alteration of the slag percentage more than the change of melting temperature. The response optimizer demonstrated that the optimal condition was the melting temperature of 500°C coupled with the ZinCrex EP7119 flux achieving the lowest slag percentage of 1.672%, with the 95% confidence interval ranging from 0.643% to 2.701%.

In this paper, Shockley-Read-Hall (SRH) lifetime depth profiles in the drift layer of 10 kV SiC PiN diodes are calculated after MeV proton implantation. It is assumed that the carbon vacancy will be the domination trap for charge carrier recombination and the SRH lifetime is calculated with defect parameters from the literature and proton-induced defect distributions deduced from SRIM calculations. The lifetime profiles are imported to Sentaurus TCAD and static and dynamic simulations using tailored lifetime profiles are carried out to study the electrical effect of proton implantation parameters. The results are compared to measurements, specializing on optimization of the trade off between on-state and turn-off losses, represented by the forward voltage drop, VT, and reverse recovery charge, Qrr, respectively. Both the simulated and measured IV characteristics show that increasing proton dose, or energy, has the effect on increasing forward voltage drop and on-state losses, while simultaneously, the localized SRH lifetime drop decreases the plasma level, increases the speed of recombination and decreases reverse recovery charge. Finally, TCAD simulations with different combinations of proton energies and fluences are used to optimize the trade-off between static and dynamic performances. Reverse recovery charge and forward voltage drops of these groups of diodes are plotted together, showing that a medium energy which induces the most defects in the depletion region relatively close to the anode gives the best dynamic performances, with a minimum cost of static performance.

In this paper, a suitable process technology is employed to fabricate a new open gate silicon carbide-based junction field-effect transistor (OG-4H-SiC-JFET) intended to be used for all types of biochemical sensing applications. The main focus is dedicated to the fabrication steps and specifically the plasma etching of the SiC as it is the key step to pattern the device components. All necessary I-V characteristics (IDS-VDS and IDS-VGS) have been derived and show acceptable electrical performance. Furthermore, the electrical characteristics of the OG-4H-SiC JFET were simulated using 3D Silvaco ATLAS and are in line with the experimental electrical characteristics. The efficacity and simplicity of the process described in this paper is the first step for future development of biochemical sensors based on SiC-FETs.

In this project, the surface structure of III-V semiconductor, GaAs, was altered to enhance the optical and electronic properties of the semiconductor. This project involved the designing and fabrication of non-porous and porous GaAs structures using SILVACO TCAD tools. The porous GaAs with different pore depth were designed and simulated to investigate the effect of pore depth on the optical and electrical properties of GaAs semiconductor. The pore depth of porous GaAs structure was varied with 2, 4, 6 and 8 μm. The porous GaAs structures were then tested for the metal-semiconductor-metal (MSM) photodetector device application. The non-porous and porous GaAs MSM photodetectors were compared systematically through current-voltage (I-V) characteristics, current gain, and spectral response. The result showed that the porous GaAs MSM photodetector has better performance in terms of electrical and optical properties than the non-porous photodetector. Amongst the MSM GaAs photodetectors, the porous GaAs photodetector with pore depth of 6 μm obtained the highest current gain value of 3.22. While for optical properties, the spectral response showed the current intensity of 11.370 µA which was recorded at the peak wavelength of 880 nm. Therefore, porous GaAs showed good potential and can be used for optoelectronic device applications such as MSM photodetector.

The low confinement losses, relatively high nonlinearity, and wideband ultra-flattened chromatic dispersion are the crucial properties of the PCFs. Thus, in this research, a comprehensive study has been conducted to design a novel Octagonal PCF (Photonic Crystal Fiber) microstructure with an ultra-flattened dispersion profile through a vast range of optical communication band wavelengths with a large negative dispersion of nearly 0.6635 ps/nm/km at 1550 nm. This PCF design and simulative study have been made by using COMSOL multi-physics. The guiding features of the fiber have been analyzed numerically to solve the Maxwell equation of electromagnetic field by using the full vector finite element method with cylindrically perfect to match layer for strongly absorb the outgoing waves from the computational region. Moreover, Octagonal rings in the cladding region provide better confinement and flattened dispersion in O-band (1260 nm-1360 nm) and C-band (1530 nm-1565 nm) in comparison to honeycomb or hexagonal lattice structures. Our proposed model has a nearly zero ultra-flattened dispersion of ± 0.3028 ps/nm/km in a 1290 nm to 1620 nm with wavelength range (320 nm flat band) and low confinement loss is less than 10-7 dB/km in the entire band of interest. Furthermore, this research has been presented a 7.2 μm2 effective area which is smaller than other reported fibers at 1550 nm wavelength.

In this work, the impacts of wafer doping type on structural and optical properties of black silicon (b-Si) fabricated by metal-assisted chemical etching (MACE) process are investigated. P-type and n-type mono-crystalline silicon (mono c-Si) wafers are etched in an aqueous solution of hydrofluoric acid (HF), silver nitrate (AgNO3) and deionised water (DI H2O) at room temperature and various durations from 5-20 minutes. Surface morphological results demonstrate the formation of b-Si nanowires (NWs) with average lengths of 0.4-0.8 μm for p-type wafers and 0.8-3.0 μm for n-type wafers. The higher length of the NWs for the n-type wafers is due to the minority charge carriers, which lead to a higher etching rate during the MACE process. Within the 300-1100 nm wavelength region, weighted average reflection (WAR) for the p-type and n-type wafers decreases to 6.6% and 6.4%, respectively, after 20 minutes of etching. The corresponding improvement in broadband light absorption results in maximum potential short-circuit current density (Jsc (max)) of 38.2 and 38.8 mA/cm2 for the p-type and n-type b-Si, respectively, which is an of enhancement of 39.9% and 42.1% when compared to the Jsc (max) of planar c-Si reference.

In this work, OPAL 2 is used to perform ray tracing simulation on perovskite thin films based on methylammonium lead triiodide (CH3NH3PbI3) and methylammonium lead tribromide (CH3NH3PbBr3) for solar windows. The thicknesses of both perovskite materials are varied between 100 nm and 500 nm. The ray tracing is carried out within 300-1000 nm wavelength region with AM1.5G solar spectrum as the illumination source. Perovskite solar cells based on CH3NH3PbI3 demonstrate absorption edge up to wavelength of 800 nm. The short-circuit current density (Jsc) improves from 11.71 mA/cm2 to 21.07 mA/cm2 due to the increased perovskite thickness from 100 nm to 500 nm. On the contrary, the average visible transmission (AVT) drops from 45% to 13%. For perovskite solar cells based on CH3NH3PbBr3, the absorption edge is shifted to wavelength of 550 nm due to the increased band gap. The Jsc increases from 3.49 mA/cm2 to 7.25 mA/cm2 when the thickness is increased from 100 nm to 500 nm. However, the AVT drops from 74% to 59%. The findings from this work show that a trade-off is required when maximizing the Jsc of the solar cells while maintaining reasonable transparencies through the solar windows.

Single point incremental forming process, which is also known as SPIF, that forms from one direction. SPIF process was used for milling an aluminum metallic sheet. In this paper, an aluminum (A5052) sheet was formed in a conical shape by the SPIF process. The A5052 sheet was deformed by the computer numerical control (CNC) technology in the T60 series milling machine. The conical shape was deformed by the spiral toolpath in the T60 series milling machine. At the surface of the A5052, lubricant grease was continuously applied manually for reducing the friction generated due to milling. Also, for decreasing the tool rotational force friction on the A5052 sheet there was the use of lubricant. Moreover, 0.1mm step-down is used for the tool path because it takes more time for forming a metallic sheet, however, it deformed the sheet smoothly. The 0.5mm step-down g-code was extracted from fusion 360. Then the metallic sheet A5052 surface was compared before and after deformation. For testing a metallic sheet A5052 the formability parameter was analyzed in the experiment part. The experiment was performed to find the optimal smooth surface from the CNC milling machine. The initial roughness value and the microscopic image were presented in the investigational part. Likewise, the comparison of points for the highest and lowest rough point was further discussed and compared throughout the experiment.

In this paper, two implementations of a SPICE-based compact model for SiC MOSFETs are presented. The two versions rely on widely adopted LEVEL-3 and BSIM 4.6.1 models, respectively. The paper discusses the feasibility of adopting these two models for the description of SiC power MOSFETs. Furthermore, after calibrating the DC characteristics on target experimental data coming from 1.7 kV-60 A MOSFETs, a comparison between the accuracy of the two is presented.

SiC power MOSFETs have made great progress since the first commercial devices were introduced in 2011, but they are still far from their theoretical limits of performance. At blocking voltages above 1200 V the specific on-resistance is limited by the drift region, but below 1200 V the resistance is dominated by the channel and the substrate, with smaller contributions from the source and JFET regions. Trench MOSFETs have smaller cell area than planar DMOSFETs, and are inherently more scalable. Both Rohm and Infineon devices have cell pitches of about 3 μm per active channel. In this paper we demonstrate a highly self-aligned fabrication process to realize deeply-scaled trench MOSFETs with a cell pitch of 0.5 μm per channel. Since the narrow gate trench is shaped like a letter “I”, we refer to these devices as “IMOSFETs”.

Indium tin oxide (ITO) thin films with 100 nm thickness were successfully deposited on soda-lime glass substrates by metal oxide electron beam evaporation at room temperature. The deposited films were post annealed via rapid thermal processor (RTP) in vacuum environment at 400 to 550 °C. All deposited ITO thin films were studied on the structural, electrical, and optical properties. Results showed that the post annealing treatment by RTP improved the crystallinity, increased crystallite size, and increased surface roughness values. Higher RTP post annealing temperature also enhanced the electrical performance that led to higher transmittance of ITO thin films.

The purpose of this research is to identify the optimal condition of the wire arc spray technique equipped with the gas atomization system using central composite design (CCD) of response surface methodology (RSM) in Minitab 18 software. Two independent parameters of the wire arc spray technique were studied, including arc voltage and air pressure. The statistical evaluations showed that both arc voltage and air pressure parameters had effects on the quality of the powder in terms of particle morphology and particle size distribution. Additionally, the arc voltage had the highest effect on particle circularity, whereas air pressure had the highest effect on particle size distribution. Finally, the optimal condition was the arc voltage and air pressure of 36.7429V and 0.5436 MPa, respectively, achieving a maximum particle circularity of 0.8284 and a targeted particle size distribution of 45 μm with the desirability of 0.7566 and 0.9928, respectively.

Conventional finite element (FE) modelling, which employed structured mesh, is unable to simulate local damage evolution at microstructure level. This paper aims to investigate the creep rupture and damage behaviour of Grade 92 steel under a creep environment using microstructural-type FE mesh. The idealised microstructures of the material were generated based on the Voronoi tessellation technique. Three notched bar specimens with different notch acuities were modelled in Abaqus v6.13 software and a ductility exhaustion based damage model was employed to estimate the damage state. The influence of the notch constraint on the ductility is accounted for in the simulation. It is found that the results obtained from the proposed technique are in good agreement with the experimental data. All the prediction points fall within the scatter band of +/- factor of 2. The damage was predicted to initiate at a distance offset from the notch tip. As the acuity increases, the damage initiation site shifts further away from the notch.

10kV+ rated 4H- Silicon Carbide (SiC) Insulated Gate Bipolar Transistors (IGBTs) have the potential to become the devices of choice in future Medium Voltage (MV) and High Voltage (HV) power converters. However, one significant performance concern of SiC IGBTs is the extremely fast collector voltage rise (dV/dt) observed during inductive turn-off. Studies on the physical mechanisms of high dV/dt in 4H-SiC IGBTs revealed the importance of collector-side design in controlling the phenomenon. In this paper we propose a novel collector-side design approach, which consists of four n-type layers with optimized doping densities and allows the control of dV/dt independently from the device performance. Further, we demonstrate a reduction of dV/dt by 87% without degrading the high switching frequency capability of the device, or the on-state performance, through the addition of two n-type epitaxial layers in the collector side, between the buffer and the drift regions.

Shear behavior of reinforced concrete beams using steel lathe scrap waste and end hooked steel fibers as fully or partially web shear reinforcement replacement was studied. Steel lathe scrap waste is generated from industrial steel waste and can be used as recycled fibers offering additional advantages towards environmental pollution reduction. To investigate their effect of reinforced concrete beam under shear behavior, ten reinforced concrete beam specimens with 1200 mm long, 200 mm wide, and 300 mm high were tested under quasi-static loading (two-point loading). The studied parameters in this investigation were types of fibers such as steel lathe waste fiber and traditional hooked steel fiber ratio and the web shear reinforcement ratio are zero% and 50%. Results observed were initial and post-cracking stiffness, maximum capacity load, vertical displacements, modes of failures, and the ductility of the specimens. It was concluded that using of steel lathe scrap waste and hooked steel fibers in concrete are advantageous, they changed the mode of failure of the beam from a brittle to a ductile mode of failure due to the ductility of steel used, whether traditional steel fiber or steel lathe waste fiber. The optimum ratio of the steel lathe scrap waste was found equal 0.5% while the optimum ratio of traditional hooked steel fiber is 1% as fractional volume.

Alginate is natural biodegradable polymers often used for wound treatments and drug delivery purposes. Due to thestructural characteristics, alginate polymers are able to form hydrogel. Alginate nanoparticles are obtained by diverse methodologies and the physical and chemical properties can be affected by production techniques and the molecules incorporated. Alginate possesses unique bioactivities such as biocompatibility, biodegradability, hydrophilicity and non-toxicity, so it has great potential for biomedical applications. Alginate based hydrogels and nanoparticles carrying active compounds are able to supply the optimal environments for wound healing and controlled drug administration including targeted or localized drug-delivery systems. In this review, the recent researches about the alginate and alginate-complex nanoparticles as potential tools for wound dressing membrane and drug delivery carriers are studied.

Due to the challenging dispersion of graphene in aqueous media, organic solvents are commonly used in conductive graphene inks. This will result in safety issues and environmental pollution. In this study, we demonstrated a green approach of graphene ink preparation through one-pot synthesis reaction that produce a hybrid reduced graphene oxide (rGO)-silver nanoparticles (AgNPs), with deionized water as solvent. The synthesized rGO-AgNPs was monitored using ultraviolet–visible (UV-Vis) spectroscopy and fourier transform infrared (FTIR). A stable dispersion of rGO-AgNPs ink was confirmed through UV-Vis analysis. FTIR result showed the removal and the reduction in the intensities of absorption bands of oxygen-containing functional groups, which indicated that graphene oxide (GO) has been successfully reduced to rGO in the hybrid ink. The printed film of rGO-AgNPs exhibited a high conductivity of 1.50 × 104 S/cm, proven that the electrical performance of the hybrid ink has been improved as compared to previously reported GO-based ink. Printed into interdigitated electrode (IDE), the impressive characteristic of our hybrid ink performed well as a high-sensitivity flexible humidity sensor.

In this work, 1200 V SiC JMOS devices with different Wsch (2 μm, 2.5 μm and 3 μm) are fabricated. The single unclamped inductive switching (UIS) tests under different Vgs_off (-5 V and 0 V) are carried out to investigate the avalanche capability. The avalanche robustness among various Wsch under same Vgs_off is also compared and analyzed by simulation. The different failure mechanisms between different Vgs_off are studied by failure analysis and simulation. The method of improving avalanche ruggedness of JMOS is proposed.

Ti15Mo7Zr15Ta1.00Si titanium alloy contained higher concentration of silicon and better elastic properties, excellent biocompatibility and lower processing cost. To investigate the influence of texture shapes and parameters of joint surfaces on the friction and wear properties under bionic lubrication conditions, three types of texture morphologies (circular, elliptical, and equal-width grating) with the same pit depth and surface coating rate were processed on a Ti15Mo7Zr15Ta1.00Si titanium alloy using a picosecond laser processing system in this study. Then, the "ceramic–metal" friction and wear tests of textured and smooth samples under lubrication with bovine serum protein were performed using a UMT-3 multifunctional friction and wear testing machine. The results showed that the surface micro-texture morphology could improve the anti-friction properties of titanium alloy artificial joint materials. The wear resistance of the circular micro-dimples improved with an increase in the circular diameter. In the elliptical micro-dimple texture morphology, the vertical arrangement of the ellipses could provide the maximum bearing capacity and best friction reduction effect, followed by the elliptical morphology and the transverse ellipse arrangement. The denser the arrangement of the equal-width bars, the better the friction reduction effect was.

The present work reviews the results of the photoluminescence (PL) study of silver-doped ZnO nanostructures synthesized by both physical and chemical methods. ZnO is a semiconductor with a binding energy of 60 meV, which ensures efficient near-band-edge band emission at a temperature of 300K and ultraviolet emission of bulk ZnO, and ZnO has a bandgap energy of 3.37 eV at room temperature. By tuning the growth process parameters of silver-doped ZnO nanostructures, the optical properties of ZnO can be controlled for use in various optoelectronic components, biosensors, blue-emitting diodes, and even white light sensors.

This paper evaluates the properties of fly ash (FA) and ground granulated blast furnace slag (GGBFS) based geopolymer mortar mixtures with waste glass sand (WGS) obtained by crushing glass bottles. A total of seven mixtures, including the partial substitution of river sand (RS) with WGS (0%, 15%, 30%, and 45%) with two alkali activator solution to binder (AAS/b) ratio groups (0.4 and 0.3), were designed. Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) were used as the alkali activators. The experimental program evaluated compressive strength, hardened density, alkali-silica reaction (ASR), drying shrinkage, and thermal conductivity of geopolymer mortar mixtures. Test results indicated that the compressive strength of the geopolymer mortar increased with the addition of WGS for AAS/b = 0.4, but it had a negative effect for AAS/b = 0.3. The FA and GGBFS-based geopolymer mortar helps to reduce the ASR expansion of the mixture containing WGS. The drying shrinkage of the geopolymer mortar decreases with the increase of the WGS content. The increase of WGS decreases the thermal conductivity of geopolymer mortar in the case of mixtures with AAS/b = 0.4, but interestingly thermal conductivity value increases in the case of mixtures with AAS/b = 0.3. The findings of this study suggest that using WGS as partial RS substitution material in geopolymer mortar offers sufficient mechanical and thermal insulation properties without causing durability issues.

We report an AEC-Q101-qualified 750V, 15 mΩ planar SiC MOSFETs with a long short circuit withstand time (SCWT) of > 9μs at VDS=400V and VGS=15V and a low specific on-resistance (RON,SP) of 2.1 mΩ.cm2 at VGS=15V designed for xEV traction inverter applications. The RDS(on) at VGS=15V increases from 15mΩ at 25 °C to 21 mΩ at 175 °C. A low turn-on (EON) and turn-off (EOFF) switching energy loss of 95.5μJ and 67μJ at IDS=75A, VDS=400V was measured at 25 °C. The gate oxide lifetime at worst case operating fields of 5MV/cm is >> 20 years.

High-strength self-compacting concrete (HSSCC) is a special concrete that mixes self-compacting and high-strength properties. The production of HSSCC may require a high cement content, which increases the cost and limits production. This research focuses on producing HSSCC using glass powder (GP) to reduce the cement content and absorb glass waste. In this research, the experimental study was conducted on the degree of eleven experimental mixtures for SCC samples. Two types of glass waste powder (bottle glass powder and window glass powder) were added as a partial substitute for cement in proportions 10-50% by weight of cement. To evaluate the performance of GP, tests on workability, compressive strength, and transport characteristics (Chloride Permeability, Sorptivity Coefficient, and Water Permeability) were performed. The results showed that adding GP to concrete improved its fresh properties, which met the requirements of EFNARC specifications. The results also showed that adding GP decreased compressive strength with an increase in replacement rates. On the other hand, the transport properties improved, and the water and chloride permeability decreased with GP compared to the reference mixture. Keywords: High-strength self-compacting concrete, bottle glass powder, window glass powder, fresh properties, compressive strength, transport properties