Optimization Of Fabrication Process Research Articles

Probing single electrons across 300-mm spin qubit wafers

Building a fault-tolerant quantum computer will require vast numbers of physical qubits. For qubit technologies based on solid-state electronic devices1–3, integrating millions of qubits in a single processor will require device fabrication to reach a scale comparable to that of the modern complementary metal–oxide–semiconductor (CMOS) industry. Equally important, the scale of cryogenic device testing must keep pace to enable efficient device screening and to improve statistical metrics such as qubit yield and voltage variation. Spin qubits1,4,5 based on electrons in Si have shown impressive control fidelities6–9 but have historically been challenged by yield and process variation10–12. Here we present a testing process using a cryogenic 300-mm wafer prober13 to collect high-volume data on the performance of hundreds of industry-manufactured spin qubit devices at 1.6 K. This testing method provides fast feedback to enable optimization of the CMOS-compatible fabrication process, leading to high yield and low process variation. Using this system, we automate measurements of the operating point of spin qubits and investigate the transitions of single electrons across full wafers. We analyse the random variation in single-electron operating voltages and find that the optimized fabrication process leads to low levels of disorder at the 300-mm scale. Together, these results demonstrate the advances that can be achieved through the application of CMOS-industry techniques to the fabrication and measurement of spin qubit devices.

PREPARATION AND JUSTIFICATION OF NANOFIBRES-LOADED MAFENIDE USING ELECTROSPINNING TECHNIQUE TO CONTROL RELEASE

Objective: The primary objective was to fabricate a novel drug delivery system capable of providing a controlled and prolonged release of antibiotics. Methods: The experimental design was formulated using Design-Expert® software (version 13), enabling systematic and efficient fabrication process optimization. The study involved the preparation of various nanofiber formulations with different ratios of the three polymers to assess their impact on drug release behavior. Mafenide, a widely used antibiotic, was chosen as the model drug for this investigation. The electrospinning process allowed for producing uniform and fine nanofibers with a high surface area, ensuring a large drug-loading capacity. The synthesized nanofibers were characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) to evaluate their morphology, chemical interactions, and thermal properties. The drug release kinetics of the antibiotic-loaded nanofibers were studied under different physiological conditions to assess their sustained release behavior. Results: The final nanofiber formula was successfully prepared using the electrospinning technique. The Fourier Transform Infrared Spectroscopy (FTIR) analysis was achieved to confirm the possibility of chemical interaction and bond formation between mafenide and the polymers. Present. The SEM picture of the optimized nanofiber formula showed the homogeneity and excellent entanglement of the electrospun nanofibers at a resolution of 5 µm. PVA/chitosan/HPMC and mafenide pure drug have been successfully fabricated with sufficient strength to resist swelling after absorbing wound exudate. The polymer network becomes more compact when chitosan and Hydroxypropyl Methyl Cellulose (HPMC) are combined with polyvinyl alcohol (PVA), enabling regulated swelling during solvent ingress. The polymer composite's three-dimensional network influenced how quickly the medication was released from the matrix. Sample 2's polymer network traps the medication, gradually releasing after controlled swelling, resulting in a sustained release profile compared to blank sample according to the cumulative release (%) study of mafenide loaded nanofiber and mafenide drug blank sample. Conclusion: This research successfully demonstrated the fabrication of sustained-release antibiotic nanofibers using electrospinning and three biocompatible polymers. The systematic optimization approach using Design-Expert® software proved effective in tailoring the drug release behavior of nanofibers. The developed drug delivery system holds great promise for pharmaceutical applications, particularly in improving antibiotic therapies and patient care.

Spin-dependent recombination affected by post-annealing of organic photovoltaic devices

Organic photovoltaic devices (OPVs) are attracting attention because of recent rapid enhancement of their power conversion efficiency. For further improvement, optimization of fabrication processes is one useful path to a solution. During OPV fabrication, particularly of the bulk heterojunction active layer, annealing treatments contribute to the device performance. Many studies have examined annealing-related properties. However, further research must clarify how paramagnetic species in the devices play their roles by annealing. Using well-known OPVs, we investigated the relation between spin-dependent recombination (SDR) current and the paramagnetic species, which vary the numbers by post-annealing with active layers consisting of poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM). A simultaneous detection method of electron spin resonance (ESR) and electrically detected magnetic resonance (EDMR), which we originally developed, was applied to OPVs for the first time ever reported. Results show that PC61BM anion radicals generated by post-annealing of P3HT:PC61BM OPVs with a lithium fluoride (LiF)/aluminum (Al) electrode do not contribute to the SDR current at the interface and that P3HT cation radicals enhance the SDR current. By contrast, devices with an Al electrode without LiF decrease the total SDR current, although the quantities of cation radical molecules do not vary. This finding suggests that changes of the hole blocking layer in the devices caused by the annealing treatment affect the size of capture cross sections of P3HT cation radicals. Our new method of quantitative observation of the EDMR changes through the ESR signals is expected to be useful for investigating the capture cross sections in OPVs.

Multiscale Fabrication Process Optimization of DFB Cavities for Organic Laser Diodes.

In the context of the quest for the Organic Laser Diode, we present the multiscale fabrication process optimization of mixed-order distributed-feedback micro-cavities integrated in nanosecond-short electrical pulse-ready organic light-emitting diodes (OLEDs). We combine ultra-short pulsed electrical excitation and laser micro-cavities. This requires the integration of a highly resolved DFB micro-cavity with an OLED stack and with microwave electrodes. In a second challenge, we tune the cavity resonance precisely to the electroluminescence peak of the organic laser gain medium. This requires precise micro-cavity fabrication performed using e-beam lithography to pattern gratings with a precision in the nanometer scale. Optimal DFB micro-cavities are obtained with 300 nm thick hydrogen silsesquioxane negative-tone e-beam resist on 50 nm thin indium tin oxide anode exposed with a charge quantity per area (i.e., dose) of 620 µC/cm2, developed over 40 min in tetramethylammonium hydroxide diluted in water. We show that the integration of the DFB micro-cavity does not hinder the pulsed electrical operability of the device, which exhibits a peak current density as high as 14 kA/cm2.

Unraveling the pivotal role of heterointerfaces on oxide ion transport in solid oxide fuel cells

Overcoming fundamental key issues affecting performance and stability has been recognized as the most important challenge for the commercialization of solid oxide fuel cells (SOFCs). Here, we employed a multipronged approach based on advanced nanoscale analyses coupled with electrochemical evaluation to elucidate the interrelation among ohmic resistance, oxide ion transport, and cation interdiffusion mainly occurring at the interlayer-electrolyte heterointerfaces. The presence of an interdiffusion layer (IDL), formed from the interdiffusion of Ce, Gd, and Zr during high-temperature sintering of conventional screen-printed gadolinia-doped ceria (GDC) interlayer on yttria-stabilized zirconia (YSZ) electrolyte, inadvertently acts as a major barrier to oxide ion transport and results in a significant increase of the ohmic resistance. An effective way to suppress the IDL formation and its oxide ion blocking effect is by alternatively fabricating the GDC interlayer using pulsed laser deposition (PLD), whereby dense layers prepared at a relatively lower deposition temperature without post-growth sintering can be obtained. Consequently, the cell's ohmic resistance is drastically lowered and a significant improvement in cell performance is achieved. These results have major implications for the selection and optimization of cell fabrication processes to mitigate degradation issues associated to heterointerfaces.

Machine Learning Assisted Optimization of Perovskite Thin Film Fabrication Process and Assessment of Feature Importance

Machine Learning Assisted Optimization of Perovskite Thin Film Fabrication Process and Assessment of Feature Importance

Pore-scale modeling and investigation on the effect of calendering on lithium-ion battery cathodes

The cathode of lithium-ion batteries (LIBs) is a porous electrode that has a crucial influence on cell performance and durability. In making the electrode, a metal foil is first coated with a cathode slurry and dried. The electrode then undergoes a hard-pressing by rollers, i.e., calendering process. In the present study, the effects of calendering on the cathode's effective transport properties and its impact on the battery's charging performance are investigated using a multiscale approach. Microscopic images of LiNi0.8Co0.1Mn0.1O2 samples are obtained using X-ray computed tomography and SEM. This material's three-dimensional microstructure is generated using a numerical reconstruction algorithm based on the distribution characteristics of active material, additives, and pores observed from the microscopic images. Pore-scale simulations are performed on models of various calendering ratios (CRs) to evaluate the pore distribution, effective lithium-ion diffusivity, and electrical conductivity of the cathode material at different CRs. The computed effective transport properties of the cathode are applied to a macroscopic model to study the charging performance of LIBs at various CRs. It is found that the battery performance increases with CR and reaches optimal electrochemical performance at CR = 20 %. When the cathode is calendered to CR = 35 %, the battery's charging performance deteriorates, and this effect is more pronounced at high charging rates. The present study demonstrates a multiscale approach combining experiment characterization and pore-scale simulation for investigating the effects of calendering on LIB cathode. This approach can be employed for the future optimization of LIB fabrication processes.

Demonstration of avalanche capability in 800 V vertical GaN-on-silicon diodes

High-quality pseudo-vertical p–n diodes using a GaN-on-silicon heterostructure are reported. An optimized fabrication process including a beveled deep mesa as edge termination and reduced ohmic contact resistances enabled high on-state current density and low on-resistance. A uniform breakdown voltage was observed at 830 V. The positive temperature dependence of the breakdown voltage clearly indicates the avalanche capability, reflecting both the high material and processing quality of the vertical p–n diodes. The Baliga figure of merit, around 2 GW cm−2, which is favorably comparable to the state-of-the-art, combined with avalanche capability paves the way for fully vertical GaN-on-Silicon power devices.

High reliability of piezoresistive pressure sensors by wafer to wafer direct bonding at room temperature

As a micro-component for detecting and acquiring pressure data, piezoresistive pressure sensors are widely used in the microelectronic industry. Enhancing the sensitivity and reliability of piezoresistive pressure sensors can be achieved with optimized fabrication process and advanced techniques. However, in previous studies, there is limited information and knowledge of the relationship between the sensor performances and their fabrication process. In this study, we further optimized the fabrication process for piezoresistive pressure sensors, achieving a significantly higher stability of the pressure sensor compared with that of the commercial products obtained based on the standard test of “Pressure & High temperature Operating Life Test.” A detailed analysis revealed that both the designed structure of the piezoresistive pressure sensor and the preliminary thermal treatment conditions for tetraethylorthosilicate (TEOS) oxide substrate are critical factors that contribute to the improved performance of the pressure sensors. After low-temperature annealing, the atomic scale characterization of the interfaces between different material layers of the sensor showed well-proportioned interfaces. Furthermore, reducing water content in the sensors through high-temperature annealing is crucial for improving the stability of the piezoresistive pressure sensors.

Performances of Nano-Structured Cu2O Thin Films Electrochemically Deposited on ITO Substrates in Lactate Bath as Liquid Petroleum Gas Sensors

The investigations are focused on structural and surface morphological features and their influence on electrical and wetting characteristics against liquid petroleum gas (LPG) sensing of synthesized nanostructured cuprous oxide (Cu2O) thin films grown by electrochemical deposition (ECD) on indium tin oxide (ITO) glass substrates in lactate bath (pH 10). p-Cu2O films revealed a cubical-tetrahedron nano-scale polycrystalline grain distribution (average grain size: 64.2 nm, inter planer spacing: 0.24 nm) that exhibited dominance in the crystallographic plane (111). LPG sensing evaluations of p-Cu2O/ITO done at 70 °C constant temperature with 100% LPG at 5 cc min−1 flow rate, showed excellent gas sensor response, recovery, and stability over time due to its moderate wetting behavior (average contact angle: ∼86°). AC impedance measurements carried out at room temperature demonstrated an ionic to electronic conduction variation from 100 Hz to 1 MHz, due to adsorption/desorption of LPG molecules (CnH2n+2) and oxygen species on the nano-particles surface. Cu2O/ITO flat band potential was found to be higher than its’ ambient state after exposure to LPG with an increment in acceptor density. Overall, this efficient LPG sensing could be attributed to the interfacial properties of Cu2O thin films and ITO substrates, that provide an optimized fabrication process of nano-structured Cu2O thin films.

2 GPa H13 steels fabricated by laser powder bed fusion and tempering: Microstructure, tensile property and strengthening mechanism

The successful manufacture of crack-free and highly dense H13 tool steel using laser powder bed fusion (LPBF) has been widely reported. Although the phases contain only martensite and some (<20 %) of residual austenite (RA), the differences in tensile properties are very large in previous studies. Here, the microstructure and tensile properties of the LPBF-fabricated H13 steels with different heat treatments were comparatively studied. Tensile strengths ranged ∼2.0–2.2 GPa for the optimal as-built and direct-tempered samples. By increasing the heat input, the RA content was reduced to 0.1 % and the microstructure contained only hierarchically fine martensite with improved tensile properties and anisotropy. Based on the full-martensitic microstructure in the optimal as-built samples, secondary hardening was achieved by direct tempering at 530–590 °C with tensile strengths of ∼2.1–2.2 GPa and improved elongations (4.93–6.43 %). The optimal direct-tempered samples yielded higher tensile strengths compared to the standard heat-treated counterparts. For the direct-tempered samples, the substantial retaining of the fine martensitic structure and high density of dislocations introduced by LPBF was the key to the excellent properties rather than the precipitates. This work elucidated the effect of the LPBF process, direct tempering, and standard heat treatment on the tensile property of H13 steel. It is concluded that process optimization for LPBF fabrication of H13 steel requires not only defect avoidance but also fine martensite and low-content RA. On this base, the LPBF-prepared H13 steel can be directly tempered to further obtain components with excellent tensile properties, which are superior to the standard heat-treated counterparts.

Machine‐Learning Accelerating the Development of Perovskite Photovoltaics

Perovskite solar cells (PSC) are a potential candidate for next‐generation photovoltaic technology. Despite the significant advancements in the field of PSCs, the ongoing development of stable and efficient metal halide perovskite materials, along with their successful integration into photovoltaic applications, remains challenges. These challenges originate from the diverse range of device structures and perovskite compositions, requiring meticulous consideration and optimization. Traditional trial‐and‐error methods are characterized by their sluggishness and labor‐intensive nature. Recently, the emergence of extensive datasets and advancements in computer hardware have facilitated the utilization of machine learning (ML) across multiple domains, including in various fields for material discovery and experimental optimization. Herein, the fundamental procedure of ML is briefly introduced, and latest progress of ML in the materials development and solar cell fabrication is comprehensively reviewed. The utilization of ML in PSCs at all stages of design can be categorized into four main areas: screening perovskite material, fabrication process optimization, device structure optimization, and understanding mechanism. The challenges and outlooks on the future development of ML are finally discussed. It is highly expected that this review can offer valuable guidance for the design and development of highly efficient and stable PSCs.

Effect of electrolyte composition and deposition voltage on the deposition rate of copper microcolumns jet electrodeposition

Jet electrodeposition (Jet ECD) is widely recognized for its potential to achieve high deposition rates and adequate field fixation. Currently, the rapid deposition of microscale copper structures remains a significant challenge. In this study, we address this challenge by employing a custom-made microcapillary glass nozzle and optimizing key plating parameters, including H2SO4, CuSO4, KCl concentration, and applied voltage. Through systematic experimentation, we successfully deposited well-formed copper microcolumns with a diameter of 70 μm at a deposition rate of 19.8 μm/s. We discovered that higher concentrations of H2SO4, greater voltage, and the addition of Cl- ions were effective in increasing the deposition speed. Furthermore, a higher concentration of CuSO4 led to improved surface morphology. Additionally, we conducted COMSOL simulations to investigate the influence of voltage and conductivity on the deposition speed. Our research results contribute to the understanding and optimization of rapid fabrication processes for copper microstructures through jet electrodeposition at the microscale.

Boosting photoelectrochemical performance of CuFeO2/CuO photocathode by modulating heterojunction architecture and oxygen vacancies

This study aims to enhance the PEC properties of CuFeO2 nanosheets by constructing closely bonded CuFeO2/CuO heterostructures. CuO crystal-structured films were prepared using the sol-gel spin-coating method, wherein the annealing temperature was varied to modulate the content of oxygen vacancies. Compared to pristine CuFeO2 and two tandem architectures, the CuFeO2@VO-CuO core-shell architecture outperformed by yielding a photocurrent density of 68 μA/cm2, which marks an almost 8.5, 1.36 and 2.27 times enhancement. Experimental results verified solid atomic-level contact bonding at the CuFeO2@VO-CuO junction, thereby augmenting overall efficiency. Through the optimized fabrication process of the CuFeO2@VO-CuO core-shell heterostructure, carrier concentration and transport and electron-hole pair separation saw substantial improvement, further boosting its PEC performance. Critically, the presence of oxygen vacancies in the CuFeO2@VO-CuO heterostructure played a pivotal role. Oxygen vacancies eliminated potential traps for captured electrons at the interface and suppressed the formation of unoccupied interface states, reducing recombination of photogenerated electron-hole pairs. Moreover, oxygen vacancies facilitated conduction band alignment, promoting efficient separation and rapid transfer of photogenerated electron-hole pairs. In conclusion, the CuFeO2@VO-CuO core-shell heterostructure achieves efficient separation and transfer of photogenerated electron-hole pairs while effectively suppressing recombination, thanks to the synergy between the interfacial electric field and oxygen vacancies.

Fabrication process optimization of nHA–CNTs-reinforced PEEK hybrid nanocomposite

Compression molding is the leading fabrication process for polymer composites. The settings of process parameters highly influence the mechanical properties of composites. This study optimized the ball-mixing and compression-molding process parameters for the fabrication of hybrid nanocomposites based on polyetheretherketone (PEEK), multiwalled carbon nanotubes (MWCNTs) and nano-hydroxyapatite using the Taguchi method. The elastic modulus examined using the nanoindentation method of static mechanical analysis was taken as the output response variable. The optimum levels of mixing time, mold temperature, mold pressure and holding time process parameters for the maximum elastic modulus were found to be 90 min, 400°C, 150 bar and 15 min, respectively. The analysis of variance technique showed that the mold temperature had the highest contribution (46.82%) in enhancing the elastic modulus to the largest value. The elastic modulus and hardness of the PEEK-based hybrid nanocomposite with 30 wt.% nHA and 3 wt.% MWCNTs were observed to be 83 and 65% higher than those of pure PEEK, respectively. The hydrophilicity of PEEK was improved with the reinforcement of nHA, attributed to the presence of oxygen-containing functional groups in the chemical structure of nHA.

Support Vector Regression Model for Determining Optimal Parameters of HfAlO-Based Charge Trapping Memory Devices

The production and optimization of HfAlO-based charge trapping memory devices is central to our research. Current optimization methods, based largely on experimental experience, are tedious and time-consuming. We examine various fabrication parameters and use the resulting memory window data to train machine learning algorithms. An optimized Support Vector Regression model, processed using the Swarm algorithm, is applied for data prediction and process optimization. Our model achieves a MSE of 0.47, an R2 of 0.98856, and a recognition accuracy of 90.3% under cross-validation. The findings underscore the effectiveness of machine learning algorithms in non-volatile memory fabrication process optimization, enabling efficient parameter selection or outcome prediction.

Establishing a Framework for Fused Filament Fabrication Process Optimization: A Case Study with PLA Filaments.

Developments in polymer 3D printing (3DP) technologies have expanded their scope beyond the rapid prototyping space into other high-value markets, including the consumer sector. Processes such as fused filament fabrication (FFF) are capable of quickly producing complex, low-cost components using a wide variety of material types, such as polylactic acid (PLA). However, FFF has seen limited scalability in functional part production partly due to the difficulty of process optimization with its complex parameter space, including material type, filament characteristics, printer conditions, and "slicer" software settings. Therefore, the aim of this study is to establish a multi-step process optimization methodology-from printer calibration to "slicer" setting adjustments to post-processing-to make FFF more accessible across material types, using PLA as a case study. The results showed filament-specific deviations in optimal print conditions, where part dimensions and tensile properties varied depending on the combination of nozzle temperature, print bed conditions, infill settings, and annealing condition. By implementing the filament-specific optimization framework established in this study beyond the scope of PLA, more efficient processing of new materials will be possible for enhanced applicability of FFF in the 3DP field.

Fabrication of GeSn Nanowire MOSFETs by Utilizing Highly Selective Etching Techniques

Germanium–tin (GeSn) epitaxy layer was prepared on an 8-in SOI wafer with a Ge buffer layer. The etching rates of different solutions for the GeSn layer were investigated. The ammonia peroxide mixture can remove the Ge buffer layer with high efficiency and selectivity to the GeSn layer. Heated ammonia solution is able to etch the Si layer without damaging the GeSn layer significantly. The two-step etching process developed in this study is conducive to achieving GeSn nanowires (NWs) by selectively etching the Ge buffer and Si bottom layers. GeSn NWFETs were fabricated and measured. The strain of the GeSn NW channels is preserved with the optimized fabrication process proposed in this study.

PROCESSING REMOVABLE ORTHODONTIC APPLIANCE FOR SINGLE TOOTH ANTERIOR CROSSBITE USING EXPANSION SCREW

Background: Anterior crossbite is a case that when upper anterior are positioned palatally than lower anterior teeth in centric occlusion. Orthodontic appliances using expansion screw could be solution for tooth anterior crossbite treatment. Purpose: To figure out the optimal fabrication process of orthodontic appliances in single tooth anterior crossbite case using expansion screw. Case analysis: Dental laboratory provided the maxillary dental appliance with single tooth anterior crossbite on teeth 21. Dental technician also received orthodontic appliance using expansion screw. Result: Orthodontic appliance design was Adams claps on teeth 16, 26, labial bow on teeth 13, 12, 11, 21, 22, 23. Additional posterior bite plane, also expansion screw was located on maxillary left first incisor, palatal section. Conclusion: Design and making orthodontic appliances using expansion screw begins with drawing design, positioning Adams clasps and labial bow sectional screw mini mounting, then acrylic packing. Final step was finishing polishing acrylic plate.

FABRICATION OF SIMPLE SPACE REGAINER FOR SPACE LOSS CASE

Background: Anterior crossbite is a case that when upper anterior are positioned palatally than lower anterior teeth in centric occlusion. Orthodontic appliances using expansion screw could be solution for tooth anterior crossbite treatment. Purpose: To figure out the optimal fabrication process of orthodontic appliances in single tooth anterior crossbite case using expansion screw. Case analysis: Dental laboratory provided the maxillary dental appliance with single tooth anterior crossbite on teeth 21. Dental technician also received orthodontic appliance using expansion screw. Result: Orthodontic appliance design was Adams claps on teeth 16, 26, labial bow on teeth 13, 12, 11, 21, 22, 23. Additional posterior bite plane, also expansion screw was located on maxillary left first incisor, palatal section. Conclusion: Design and making orthodontic appliances using expansion screw begins with drawing design, positioning Adams clasps and labia bow sectional screw mini mounting, then acrylic packing. Final step was finishing polishing acrylic plate.