Accelerating interest in silicon nitride thin film material system continues in both academic and industrial communities due to its highly desirable physical, chemical, and electrical properties and the potential to enable new device technologies. As considered here, the silicon nitride material system encompasses both non-hydrogenated (SiNx) and hydrogenated (SiNx:H) silicon nitride, as well as silicon nitride-rich films, defined as SiNx with C inclusion, in both non-hydrogenated (SiNx(C)) and hydrogenated (SiNx:H(C)) forms. Due to the extremely high level of interest in these materials, this article is intended as a follow-up to the authors' earlier publication [A. E. Kaloyeros, F. A. Jové, J. Goff, B. Arkles, Silicon nitride and silicon nitride-rich thin film technologies: trends in deposition techniques and related applications, ECS J. Solid State Sci. Technol., 6, 691 (2017)] that summarized silicon nitride research and development (R&D) trends through the end of 2016. In this survey, emphasis is placed on cutting-edge achievements and innovations from 2017 through 2019 in Si and N source chemistries, vapor phase growth processes, film properties, and emerging applications, particularly in heterodevice areas including sensors, biointerfaces and photonics.
The Electrochemical Society (ECS) was founded in 1902 to advance the theory and practice at the forefront of electrochemical and solid state science and technology, and allied subjects.
ISSN: 2162-8777
JSS is a peer-reviewed journal covering fundamental and applied areas of solid-state science and technology, including experimental and theoretical aspects of the chemistry, and physics of materials and devices.
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Alain E. Kaloyeros et al 2020 ECS J. Solid State Sci. Technol. 9 063006
Roy Knechtel et al 2021 ECS J. Solid State Sci. Technol. 10 074008
Wafer bonding is an important process step in microsystem technologies for processing engineered substrates and for capping. Usually, the work and literature are focused on the bonding of the main wafer area. However, in recent years MEMS technologies have become more complex, with more process steps after wafer bonding. Accordingly, the wafer edge is becoming more and more important, and must be engineered. Methods for realizing this are discussed in this paper.
Sandeep Arya et al 2021 ECS J. Solid State Sci. Technol. 10 023002
ZnO has several potential applications into its credit. This review article focuses on the influence of processing parameters involved during the synthesis of ZnO nanoparticles by sol-gel method. During the sol-gel synthesis technique, the processing parameters/experimental conditions can affect the properties of the synthesized material. Processing parameters are the operating conditions that are to be kept under consideration during the synthesis process of nanoparticles so that various properties exhibited by the resulting nanoparticles can be tailored according to the desired applications. Effect of parameters like pH of the sol, additives used (like capping agent, surfactant), the effect of annealing temperature and calcination on the morphology and the optical properties of ZnO nanoparticles prepared via sol-gel technique is analyzed in this study. In this study, we tried to brief the experimental investigations done by various researchers to analyze the influence of processing parameters on ZnO nanoparticles. This study will provide a platform to understand and establish a correlation between the experimental conditions and properties of ZnO nanoparticles prepared through sol-gel route which will be helpful in meeting the desired needs in various application areas.
Kartika A. Madurani et al 2020 ECS J. Solid State Sci. Technol. 9 093013
Graphene is a thin layer carbon material that has become a hot topic of research during this decade due to its excellent thermal conductivity, mechanical strength, current density, electron mobility and surface area. These extraordinary properties make graphene to be developed and applied in various fields. On this basis, researchers are interested to find out the methods to produce high quality graphene for industrial use. Various methods have been developed and reported to produce graphene. This paper was designed to summarize the development of graphene synthesis methods and the properties of graphene products that were obtained. The application of graphene in the various fields of environment, energy, biomedical, sensors, bio-sensors, and heat-sink was also summarized in this paper. In addition, the history, challenges, and prospects of graphene production for research and industrial purposes were also discussed.
Chunlin Zhou et al 2021 ECS J. Solid State Sci. Technol. 10 027005
In recent years, betavoltaic batteries have become an ideal power source for micro electromechanical systems. Betavoltaic battery is a device that converts the decay energy of beta emitting radioisotope sources into electrical energy using transducers. They have the advantages of high energy density, long service life, strong anti-interference ability, small size, light weight, easy miniaturization and integration, thus it has become a research hotspot in the field of micro energy. However, to date, the low energy conversion efficiencies as well as technological limitations of betavoltaic batteries impede their further application. In this review, the theory of betavoltaic energy conversion and recent understanding of the ideal material and structure design of the betavoltaic batteries for efficient exciton production, dissociation and charge transport is described, as well as recent attempts to realize optimum results. This review article concludes by identifying the remaining challenges for the improvement of battery performance and by providing perspectives toward real application of betavoltaic batteries.
Yu-Cheng Syu et al 2018 ECS J. Solid State Sci. Technol. 7 Q3196
Biosensor research has been addressed as an interested field recently. Within different kinds of developed biosensing technologies, field-effect transistor (FET) based biosensors stand out due to their attractive features, such as ultra-sensitivity detection, mass-production capability, and low-cost manufacturing. To promote understandings of the FET based biosensing technology, in this review, its sensing mechanism is introduced, as well as major FET-based biosensing devices: ion sensitive field-effect transistor (ISFET), silicon nanowire, organic FET, graphene FET, and compound-semiconductor FET. In addition to FET-based biosensing devices, clinical applications, such as cardiovascular diseases (CVDs), cancers, diabetes, HIV, and DNA sequence, are also reviewed. In the end, several critical challenges of FET-based biosensing technology are discussed to envision next steps in healthcare technologies.
J. Müller et al 2015 ECS J. Solid State Sci. Technol. 4 N30
Bound to complex perovskite systems, ferroelectric random access memory (FRAM) suffers from limited CMOS-compatibility and faces severe scaling issues in today's and future technology nodes. Nevertheless, compared to its current-driven non-volatile memory contenders, the field-driven FRAM excels in terms of low voltage operation and power consumption and therewith has managed to claim embedded as well as stand-alone niche markets. However, in order to overcome this restricted field of application, a material innovation is needed. With the ability to engineer ferroelectricity in HfO2, a high-k dielectric well established in memory and logic devices, a new material choice for improved manufacturability and scalability of future 1T and 1T-1C ferroelectric memories has emerged. This paper reviews the recent progress in this emerging field and critically assesses its current and future potential. Suitable memory concepts as well as new applications will be proposed accordingly. Moreover, an empirical description of the ferroelectric stabilization in HfO2 will be given, from which additional dopants as well as alternative stabilization mechanism for this phenomenon can be derived.
Alain E. Kaloyeros and Barry Arkles 2023 ECS J. Solid State Sci. Technol. 12 103001
In Part I of a two-part report, we provide a detailed and systematic review of the latest progress in cutting-edge innovations for the silicon carbide (SiC) material system, focusing on chemical vapor deposition (CVD) thin film technologies. To this end, up-to-date results from both incremental developments in traditional SiC applications as well major advances in novel SiC usages are summarized. Emphasis is placed on new chemical sources for Si and C, particularly in the form of single source SiC precursors as well as emerging molecular and atomic scale deposition techniques, with special attention to their effects on resulting film properties and performance. The review also covers relevant research and development efforts as well as their potential impact on and role in the introduction of new technological applications. Part II will focus on findings for physical vapor deposition (PVD) as well as other deposition techniques.
Madhulika Bhagat et al 2021 ECS J. Solid State Sci. Technol. 10 063011
Copper nanomaterials due to their unique properties are rapidly finding place as an important component of next-generation material in various sectors such as electronics, machinery, construction, engineering, pharmaceutical, agriculture, energy, environment etc In fact in past decades, researchers have devoted several studies to Cu nanomaterials, and have achieved many innovative results from synthesis to applications, highlighting its immeasurable potential for extensive practical and theoretical applications holding great promises. This review emphasises on the recent progress made in synthesis of copper nanoparticles by various techniques such as physical, chemical and biological methods. The application section describes their utility in several sectors including agriculture, environment, construction, electronics etc Moreover, the emphasis was also laid to understand the uptake mechanism of the copper nanoparticles by plants, the toxicity caused at higher concentrations and the associated implications of exposure to both human and environmental health, including the challenges and difficulties to be addressed in the future.
G. S. Oehrlein et al 2015 ECS J. Solid State Sci. Technol. 4 N5041
The ability to achieve near-atomic precision in etching different materials when transferring lithographically defined templates is a requirement of increasing importance for nanoscale structure fabrication in the semiconductor and related industries. The use of ultra-thin gate dielectrics, ultra thin channels, and sub-20 nm film thicknesses in field effect transistors and other devices requires near-atomic scale etching control and selectivity. There is an emerging consensus that as critical dimensions approach the sub-10 nm scale, the need for an etching method corresponding to Atomic Layer Deposition (ALD), i.e. Atomic Layer Etching (ALE), has become essential, and that the more than 30-year quest to complement/replace continuous directional plasma etching (PE) methods for critical applications by a sequence of individual, self-limited surface reaction steps has reached a crucial stage. A key advantage of this approach relative to continuous PE is that it enables optimization of the individual steps with regard to reactant adsorption, self-limited etching, selectivity relative to other materials, and damage of critical surface layers. In this overview we present basic approaches to ALE of materials, discuss similarities/crucial differences relative to thermal and plasma-enhanced ALD, and then review selected results on ALE of materials aimed at pattern transfer. The overview concludes with a discussion of opportunities and challenges ahead.
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Jintao Sun et al 2024 ECS J. Solid State Sci. Technol. 13 051003
Developing high-performance anion-exchange membrane fuel cells requires stable and highly active oxygen reduction (ORR) catalysts. To fabricate cheap and efficient porous carbon materials for ORR, heteroatom-doped carbon nanorods were synthesized by pyrolyzing Bacillus subtilis. The obtained carbon material maintained the uniformly distributed nanorods as original Bacillus subtilis and had inherent doped heteroatom. The obtained BS-2.0 had the highest specific surface area (209.04 m2 g−1) and the maximum ID/IG (1.0372). Its starting potential (0.93 V vs RHE) and semi-wave potential (0.81 V vs RHE) were close to 20% commercial Pt/C, and its ultimate current density was 3.98 mA cm−2@1600 rpm. Meanwhile, the stability of cycling potentiates polarization, and methanol tolerance of BS-2.0 were all greater than 20% commercial Pt/C. It was the inherent heteroatom, well-distributed nanorods, abundant pore distribution, and large surface area that contributed to its excellent electrochemical performance.
Abdul Rauf Jamali et al 2024 ECS J. Solid State Sci. Technol. 13 053009
Over the past few decades, Polyvinyl-alcohol (PVOH)/cornstarch (CS)-based composite thin films have garnered significant interest due to their enhanced properties. Synthesis of such films relies heavily on depolymerization reactions within the solution of the PVOH/CS blends. Understanding how depolymerization affects the crystal structure and properties of these films is crucial for further improvement. This study aims to evaluate the depolymerization effects of crosslinked PVOH incorporated with CS as filler materials (with an 80:20 mass ratio) using ultrasonication at various time intervals while maintaining a constant frequency of 25 KHz. The prepared solution is then cast into thin films using blade coating. Comparative analyses were then conducted between samples subjected to ultrasonication (treated) and without ultrasonication (untreated) to assess their properties based on structural physical, mechanical, optical, and aspects of biodegradability . The investigation revealed significant changes in crystal structure and lattice strains following ultrasonication of the PVOH/CS solution when compared to untreated PVOH/CS samples. Importantly, longer ultrasonication times correlated with increased tensile strength. Additionally, the treated samples led to improvements in thin film transparency and a notable decrease in absorbance. These changes were attributed to the mechanical depolymerization induced by ultrasonication, aligning the thin films with the necessary properties for food packaging applications.
Jinhyung Lee et al 2024 ECS J. Solid State Sci. Technol. 13 054005
Single-crystal sapphire is known to be among the hardest insulators. Its mechanical properties and chemical inertness make it a challenging material to polish for the atomic-level surface smoothness required for its applications. Mechanical polish with diamond abrasives renders high removal rates but creates unacceptable levels of polish-induced gouges. Chemical mechanical polish on the other hand results in atomic smoothness but is a slow process. Hence, a combination of the two is used in the industry. In this work, we have attempted to characterize gouging and subsurface damage using atomic force microscopy, X-ray diffraction, and cross-section transmission electron microscopy on C-plane and A-plane sapphire induced by diamond abrasive mechanical polish and chemical mechanical polish with colloidal silica.
Highlights
Chemical mechanical polishing/planarization of two orientations/planes of sapphire (α-Al2O3).
Characterization of polish induced gouges - measurement of depth of gouges.
Growth of epi-layers, displays, windows for wearable electronics, etc.
Characterization of sapphire surface using TEM, XRD and AFM - quantification of results.
Use of X-ray rocking curves to determine crystal surface quality.
Hui-Hsuan Li et al 2024 ECS J. Solid State Sci. Technol. 13 053008
We have developed a method that uses a half-cycle Hf precursor adsorption to subtly dope GeO2 IL of the Hf-based gate stack through in situ plasma-enhanced atomic layer deposition. This technique can effectively reduce GeO vaporization and improve the thermal stability of the GeO2 layer. Our results indicated that the accumulation capacitance (Cacc) undergoing higher temperatures showed no noticeable increase in the capacitance-voltage (CV) curves once Hf was delicately introduced into the GeO2 layer. According to the Ge 3d spectra of X-ray photoelectron spectroscopy, we found that the IL had a signal from extra Hf-O bonds; thus, we conclude GeO evaporation can be suppressed substantially by Hf incorporation. As a result, adding metal into GeOx IL to form HfGeOx achieved a remarkably low leakage current of 9 × 10−5 A cm−2 and the lowest interface trap density (Dit) of approximately 2 × 1011 eV−1 cm−2 at 500 °C of PMA. In addition, applying this gate stack structure to device fabrication significantly reduced the leakage current of the off-state and improved the effective peak hole mobility.
Jose Lopez Ninantay et al 2024 ECS J. Solid State Sci. Technol. 13 054004
The catalytic decomposition of poly(phthalaldehyde) with a photoacid generator can be used as dry-develop photoresist, where the exposed film depolymerizes into small molecules to allow the development of features via controlled vaporization. Higher temperatures enabled shorter dry-development times, but also promoted faster photoacid diffusion that compromised pattern fidelity. Trihexylamine was used as a base quencher to counteract acid diffusion in a phthalaldehyde-propanal co-polymer photoresist. The propanal co-monomer in the polymer improves the vaporization rate because it has a higher vapor pressure than phthalaldehyde. Addition of the base quencher was found to improve the contrast, pattern fidelity, and ease-of-handling of the dry-develop resist in a direct-write UV lithography tool. The dry-development of 4 μm features was achieved with no appreciable residue. For large area features, a spatially variable exposure method was used to direct the residue away from the exposed area. The gradient exposure method was used to produce 100 μm features. Plasma etching after dry-development was also used to achieve residue-free dry-developed patterns. These results show the benefits of incorporating base additives into a dry-develop depolymerizable resist system and highlight the need for addressing residue formation.
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Anita Gupta et al 2024 ECS J. Solid State Sci. Technol. 13 047006
The main characteristics of a good pH detecting system are higher sensitivity, ease of manufacturing process, and a micro-system. Ion sensitive field effect transistors (ISFETs), which are frequently employed as biosensors, offer significant advantages, and have gained prominence in various sectors. This review has highlighted the factors influencing sensitivity in pH sensing and explored various methods to enhance the sensor's sensitivity and overall performance. Miniature sensors play a crucial role, especially in industries, biomedical and environmental applications. For accurate pH measurements in both in-vivo and in-vitro systems, as well as for the device's miniaturization, the reference electrode (RE) must be positioned precisely in an ISFET device, considering both the device's physical dimensions and the distance between the sensing surface and the RE. Hence, this review provides valuable insights into the importance of sensitivity, miniaturization, and the role of the RE in ISFET devices, contributing to the advancement and application of pH sensing technology in diverse fields.
Himanshu Prasad Mamgain et al 2024 ECS J. Solid State Sci. Technol. 13 043010
Corrosion is an undesirable electrochemical reaction that leads to material degradation and affects material properties like ductility, malleability, conductivity, etc. The consequences of corrosion are machine failure, bridge failures, buildings collapse, and significant economic losses to GDP (4-5%). Furthermore, corrosion can pose serious safety risks that result in casualties which makes minimizing the effect of corrosion a great challenge. Traditional solutions like inhibitors, design modification, and paints are available to prevent corrosion but have many limitations, such as cost, durability, stability issues, and general inefficiency. In this context, a nanostructured superhydrophobic coating (SH) is gaining attention for its corrosion prevention efficiency and other broad industrial applications. The nano air pockets present in SH coating exhibit a high contact angle due to their unique combination of high surface roughness, distinctive nanostructure, and reduced surface energy. This reduces the surface area of between the corrosive substance,water droplet and the metal surface, leading to improved efficiency in resisting corrosion. In this paper, the recent advancement in electrodeposition to develop corrosion-resistant SH coatings on copper substrate and compression with other metals with their physical, chemical, and thermal stabilities are discussed. In many papers, scientists observed different types of surface morphology, texture, and surface energy, which give different tendencies to prevent surfaces from corrosion are also disscused . The constraints in fabrication and the prospects of the coating are also highlighted.
Highlights
An overview of the applications of copper and the problem of corrosion, factors affecting corrosion, and its impact in different industries.
A broad overview of rudiments of the superhydrophobicity
Detailed analysis of fabrication of SHCs for metal protection from corrosion by electrodeposition on copper and comparisons with other metals.
Other industrial applications of corrosion-resistant superhydrophobic coating are included.
Stability, conclusion, and future perspectives in fabricating superhydrophobic coating to minimize corrosion.
Bakr Ahmed Taha et al 2024 ECS J. Solid State Sci. Technol. 13 047004
Early diagnosis through noninvasive tools is a cornerstone in the realm of personalized and medical healthcare, averting direct/indirect infection transmission and directly influencing treatment outcomes and patient survival rates. In this context, optical biochip breathomic sensors integrated with nanomaterials, microfluidics, and artificial intelligence exhibit the potential to design next-generation intelligent diagnostics. This cutting-edge tool offers a variety of advantages, including being economical, compact, smart, point of care, highly sensitive, and noninvasive. This makes it an ideal avenue for screening, diagnosing, and prognosing various high-risk diseases/disorders by detecting the associated breath biomarkers. The underlying detection mechanism relies on the interaction of breath biomarkers with sensors, which causes modulations in fundamental optical attributes, such as surface plasmon resonance, fluorescence, reflectance, absorption, emission, phosphorescence, and refractive index. Despite these remarkable attributes, the commercial development of optical biochip breathomic sensors faces challenges, such as insufficient support from clinical trials, concerns about cross-sensitivity, challenges related to production scalability, validation issues, regulatory compliance, and contrasts with conventional diagnostics. This perspective article sheds light on the cutting-edge state of optical breathomic biochip sensors for disease diagnosis, addresses associated challenges, proposes alternative solutions, and explores future avenues to revolutionize personalized and medical healthcare diagnostics.
Madhu Bala and Sushil Bansal 2024 ECS J. Solid State Sci. Technol. 13 047003
Plant leaf disease identification is a crucial aspect of modern agriculture to enable early disease detection and prevention. Deep learning approaches have demonstrated amazing results in automating this procedure. This paper presents a comparative analysis of various deep learning methods for plant leaf disease identification, with a focus on convolutional neural networks. The performance of these techniques in terms of accuracy, precision, recall, and F1-score, using diverse datasets containing images of diseased leaves from various plant species was examined. This study highlights the strengths and weaknesses of different deep learning approaches, shedding light on their suitability for different plant disease identification scenarios. Additionally, the impact of transfer learning, data augmentation, and sensor data integration in enhancing disease detection accuracy is discussed. The objective of this analysis is to provide valuable insights for researchers and practitioners seeking to harness the potential of deep learning in the agricultural sector, ultimately contributing to more effective and sustainable crop management practices.
Avinash Sharma et al 2024 ECS J. Solid State Sci. Technol. 13 047002
Multidrug resistance (MDR) is a significant global challenge requiring strategic solutions to address bacterial infections. Recent advancements in nanotechnology, particularly in the synthesis of zinc oxide nanoparticles (ZnO NPs) using natural agents as stabilizers and reducing agents, have shown promising results in combating MDR. These nanoparticles possess strong antimicrobial properties against different strains of Gram-positive and Gram-negative, making them suitable for various industries, including food, pharmaceuticals, coatings, and medical devices. ZnO-NPs work by generating reactive oxygen species, releasing zinc ions (Zn2+), disrupting the bacterial cell membrane, interfering with metabolic processes and genetic material, and inducing oxidative stress and apoptosis. However, more research is needed to refine synthesis techniques, control size and morphology, and increase antibacterial efficacy. To fully understand their potential, interactions with proteins, DNA, and bacterial cell walls must also be examined. Investigating the synergistic potential of biogenic ZnO NPs with conventional antibacterial treatments could enhance therapeutic effectiveness while minimizing the risk of resistance emergence. Here we provide insight into the advancements in biogenic synthesis of nanoparticles using bio extracts and their applications in antimicrobial resistance as well as various factors affecting the synthesis process and characterization techniques for ZnO NPs. Recent studies on the antimicrobial activity of biogenic ZnO NPs against different pathogens and their mechanisms of action are discussed. Furthermore, potential applications of biogenic ZnO NPs as antimicrobial agents are highlighted.
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Bakr Ahmed Taha et al 2024 ECS J. Solid State Sci. Technol. 13 047004
Early diagnosis through noninvasive tools is a cornerstone in the realm of personalized and medical healthcare, averting direct/indirect infection transmission and directly influencing treatment outcomes and patient survival rates. In this context, optical biochip breathomic sensors integrated with nanomaterials, microfluidics, and artificial intelligence exhibit the potential to design next-generation intelligent diagnostics. This cutting-edge tool offers a variety of advantages, including being economical, compact, smart, point of care, highly sensitive, and noninvasive. This makes it an ideal avenue for screening, diagnosing, and prognosing various high-risk diseases/disorders by detecting the associated breath biomarkers. The underlying detection mechanism relies on the interaction of breath biomarkers with sensors, which causes modulations in fundamental optical attributes, such as surface plasmon resonance, fluorescence, reflectance, absorption, emission, phosphorescence, and refractive index. Despite these remarkable attributes, the commercial development of optical biochip breathomic sensors faces challenges, such as insufficient support from clinical trials, concerns about cross-sensitivity, challenges related to production scalability, validation issues, regulatory compliance, and contrasts with conventional diagnostics. This perspective article sheds light on the cutting-edge state of optical breathomic biochip sensors for disease diagnosis, addresses associated challenges, proposes alternative solutions, and explores future avenues to revolutionize personalized and medical healthcare diagnostics.
Sangeeta Palekar et al 2024 ECS J. Solid State Sci. Technol. 13 027004
The pursuit of rapid diagnosis has resulted in considerable advances in blood parameter sensing technologies. As advances in technology, there may be challenges in equitable access for all individuals due to economic constraints, advanced expertise, limited accessibility in particular places, or insufficient infrastructure. Hence, simple, cost efficient, benchtop biochemical blood-sensing platform was developed for detecting crucial blood parameters for multiple disease diagnosis. Colorimetric and image processing techniques is used to evaluate color intensity. CMOS image sensor is utilized to capture images to calculate optical density for sensing. The platform is assessed with blood serum samples, including Albumin, Gamma Glutamyl Transferase, Alpha Amylase, Alkaline Phosphatase, Bilirubin, and Total Protein within clinically relevant limits. The platform had excellent Limits of Detection (LOD) for these parameters, which are critical for diagnosing liver and kidney-related diseases (0.27 g dl−1, 0.86 IU l−1, 1.24 IU l−1, 0.97 IU l−1, 0.24 mg dl−1, 0.35 g dl−1, respectively). Machine learning (ML) algorithms were used to estimate targeted blood parameter concentrations from optical density readings, with 98.48% accuracy and reduced incubation time by nearly 80%. The proposed platform is compared to commercial analyzers, which demonstrate excellent accuracy and reproducibility with remarkable precision (0.03 to 0.71%CV). The platform's robust stability of 99.84% was shown via stability analysis, indicating its practical applicability.
V. I. Nikolaev et al 2023 ECS J. Solid State Sci. Technol. 12 115001
The properties of orthorhombic κ-Ga2O3 films grown by Epitaxial Lateral Overgrowth (ELOG) were studied by Scanning Transmission Electron Microscopy (STEM), X-ray diffraction, capacitance-voltage profiling, Microcathodoluminescence (MCL) spectroscopy and imaging. ELOG mask was formed by deposition of SiO2 stripes on TiO2 buffer prepared on basal plane sapphire, with the stripes going along the [110] direction of sapphire. κ-Ga2O3 ELOG growth was performed using Halide Vapor Phase Epitaxy (HVPE), with ELOG wing of the structure formed by lateral overgrowth over the 20 μm-wide SiO2 stripes, while growth in between the stripes proceeded initially by vertical growth in the 5-μm-wide windows. TEM analysis showed that the material in the windows comprised 120o rotational nanodomains typical of κ-Ga2O3, while, in the wing regions, the material was single-domain monocrystalline. The films were conducting, with the net donor density close to 1013 cm−3. The data suggested the material in the windows have much higher resistance than in the wings. MCL spectra and imaging revealed much higher density of nonradiative recombination centers in the windows than in the wings.
Younghyun You et al 2023 ECS J. Solid State Sci. Technol. 12 075009
WS2 is an emerging semiconductor with potential applications in next-generation device architecture owing to its excellent electrical and physical properties. However, the presence of inevitable surface contaminants and oxide layers limits the performance of WS2-based field-effect transistors (FETs); therefore, novel methods are required to restore the pristine WS2 surface. In this study, the thickness of a WS2 layer was adjusted and its surface was restored to a pristine state by fabricating a recessed-channel structure through a combination of self-limiting remote plasma oxidation and KOH solution etching processes. The reaction between the KOH solution and WOX enabled layer-by-layer thickness control as the topmost oxide layer was selectively removed during the wet-etching process. The thickness of the WS2 layer decreased linearly with the number of recess cycles, and the vertical etch rate was estimated to be approximately 0.65 nm cycle−1. Micro-Raman spectroscopy and high-resolution transmission electron microscopy revealed that the layer-by-layer etching process had a nominal effect on the crystallinity of the underlying WS2 channel. Finally, the pristine state was recovered by removing ambient molecules and oxide layers from the surface of the WS2 channel, which resulted in a high-performance FET with a current on/off ratio greater than 106. This method, which provides a facile approach to restoring the pristine surfaces of transition-metal dichalcogenide (TMDC) semiconductors with precise thickness control, has potential applications in various fields such as TMDC-based (opto)electronic and sensor devices.
Vimal Kumar et al 2023 ECS J. Solid State Sci. Technol. 12 047001
For electrical sliding contact applications, there are important criteria such as superior tribological qualities in addition to strong electrical conductivity. This calls for the development of advanced metal matrix composites based on copper. Although adding graphite to a copper matrix results in a self-lubricating feature, the composite's strength declines. Harder ceramic particles like SiC, TiC, and Al2O3 may be used to reinforce the composite to increase its strength. This study looked at the construction of a hybrid composite made of a copper metal matrix reinforced with TiC and graphite particles. The impact of TiC (5, 10, and 15 vol.%) and graphite (5 and 10 vol.%) reinforcements on the structural, physical and mechanical characteristics of copper-TiC-graphite hybrid composites that were microwave-sintered are thoroughly explored. The consistent distribution of reinforcements in the copper matrix is seen in micrographs. In comparison to traditionally sintered composites, microwave-sintered ones showed greater relative density, sintered density, and hardness.
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Babu et al
This manuscript presents a pioneering study on enhancing analog and radio frequency performance through the implementation of negative capacitance source pocket double gate tunnel field-effect transistor. By integrating a ferroelectric material into the gate stack and introducing a fully depleted n-type pocket near the source/channel junction, we achieved significant enhancements in key metrics such as ON current (ION), switching ratio, subthreshold swing (SS), and various analog/RF parameters like transconductance (gm), cutoff frequency (fT) when compared to existing literature. Additionally, we extend our analysis to circuit-level applications such as inverter and 5-stage ring oscillator. Our findings reveal an impressive inverter delay of 1.09 ps with a gain of 104, as well as a ring oscillator operating at a frequency of 500 GHz. These results position the proposed device as an ideal candidate for high-speed, low-power applications.
Lin et al
This study reports a self-induced ferroelectric Ge-doped HfO2 (Ge:HfO2) thin film through interface reactions. In the first experiment, three treatments for forming interfacial layer (IL) were discussed through TiN/2-nm-thick Al2O3/2-nm-thick Ge:HfO2/GeO2/Ge metal-ferroelectric-insulator-semiconductor capacitors. The remnant polarization (Pr), leakage current, and interface trap density (Dit) were compared to select the most appropriate IL treatment. The results show that the in-situ ozone treatment under the standard atomic layer deposition process had the second highest 2Pr value as well as lower Dit values. Next, the thicknesses of Al2O3/Ge:HfO2 would be changed to 4/2 nm and 3/3 nm to investigate the ferroelectricity and leakage current. Although the 3-nm-thick Al2O3/3-nm-thick Ge:HfO2 shows a lower 2Pr value, the leakage current is much lower than 2-nm-thick Al2O3/2-nm-thick Ge:HfO2. The self-induced ferroelectric 3-nm-thick Ge:HfO2 thin film was then applied to fabricate Ge stacked nanowires gate-all-around field-effect transistor. The results show a steep subthreshold slope of 58 mV/dec for pFET and on-off current ratio > 105 and have high potential in low-power IC applications.
Wan et al
Breast cancer remains a considerable health challenge, affecting numerous individuals annually. This research introduces an innovative method for detecting breast cancer utilizing dual-channel test strips capable of simultaneously assessing two key biomarkers—HER2 and CA 15-3. The test strip utilized in this study is not only cost-effective but also entirely non-invasive. The reusable device employs a printed circuit board with metal-oxide-semiconductor field-effect transistor amplification and Arduino-based control to convert voltage signals from test strips into digital readings efficiently. The device utilizes double-pulse measurement instead of direct current, effectively mitigating the screening effect. The detection limit for both biomarkers is exceptionally low at 10-15 g/mL, surpassing commercial enzyme-linked immunoassay kits by four orders of magnitude. The sensor demonstrates remarkable sensitivity, with 78/dec for HER2 and 56/dec for CA 15-3. Human sample tests were conducted to validate the efficacy of the dual-channel strip, successfully distinguishing between healthy and cancerous groups. The results reveal significant p-values for both HER2 and CA 15-3 tests, underscoring the significance of this research. Note that this is a rapid testing process, completed in less than 2 seconds. These findings offer a promising avenue for swift and accurate breast cancer detection, furnishing crucial insights for early diagnosis and subsequent treatment.
Chen et al
This study investigated threshold voltage (VTH) instability in a Schottky p-GaN gate AlGaN/GaN high-electron-mobility transistor (HEMT) by using the double pulse test (DPT) with a 1-µs pulse width in the ON-state and OFF-state. OFF-state drain biases (VDS,OFF) of 100–400 V and ON-state drain currents of ID,ON 1–16 A were applied in the DPT to observe the post-DPT VTH shift. The ON-state currents did not strongly influence the device's characteristics after the DPT. However, the OFF-state voltages, particularly VDS,OFF = 100 and 200 V, exerted notable effects. A TCAD simulation was conducted to investigate the mechanism underlying the VTH shift after the DPT at various VDS,OFF and ID,ON levels.
Huo
Silicon has garnered significant attention as the primary material for solar cell preparation. Traditional alkaline etching solutions are limited to creating an upright pyramid structure on monocrystalline silicon surfaces. However, research indicates that an inverted pyramid structure exhibits superior light-trapping properties compared to the upright pyramid structure. In this study, we employed a one-step copper ion metal-assisted chemical etching process to fabricate an inverted pyramid structure on monocrystalline silicon wafers. This method allows for the customization of either inverted or upright pyramid structures by adjusting the concentration of specific solution components. Characterization of the textured silicon wafers reveals that the inverted pyramid structure exhibits lower reflectivity than both the upright pyramid structure and polished silicon. By integrating this texturing technique into the solar cell production line, we successfully produced solar cells with both inverted and upright pyramid structures. Evaluation of various solar cell parameters demonstrates that the inverted pyramid structure outperforms the upright pyramid structure, showcasing lower reflectivity and higher photoelectric conversion efficiency.
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Hui-Hsuan Li et al 2024 ECS J. Solid State Sci. Technol. 13 053008
We have developed a method that uses a half-cycle Hf precursor adsorption to subtly dope GeO2 IL of the Hf-based gate stack through in situ plasma-enhanced atomic layer deposition. This technique can effectively reduce GeO vaporization and improve the thermal stability of the GeO2 layer. Our results indicated that the accumulation capacitance (Cacc) undergoing higher temperatures showed no noticeable increase in the capacitance-voltage (CV) curves once Hf was delicately introduced into the GeO2 layer. According to the Ge 3d spectra of X-ray photoelectron spectroscopy, we found that the IL had a signal from extra Hf-O bonds; thus, we conclude GeO evaporation can be suppressed substantially by Hf incorporation. As a result, adding metal into GeOx IL to form HfGeOx achieved a remarkably low leakage current of 9 × 10−5 A cm−2 and the lowest interface trap density (Dit) of approximately 2 × 1011 eV−1 cm−2 at 500 °C of PMA. In addition, applying this gate stack structure to device fabrication significantly reduced the leakage current of the off-state and improved the effective peak hole mobility.
Jose Lopez Ninantay et al 2024 ECS J. Solid State Sci. Technol. 13 054004
The catalytic decomposition of poly(phthalaldehyde) with a photoacid generator can be used as dry-develop photoresist, where the exposed film depolymerizes into small molecules to allow the development of features via controlled vaporization. Higher temperatures enabled shorter dry-development times, but also promoted faster photoacid diffusion that compromised pattern fidelity. Trihexylamine was used as a base quencher to counteract acid diffusion in a phthalaldehyde-propanal co-polymer photoresist. The propanal co-monomer in the polymer improves the vaporization rate because it has a higher vapor pressure than phthalaldehyde. Addition of the base quencher was found to improve the contrast, pattern fidelity, and ease-of-handling of the dry-develop resist in a direct-write UV lithography tool. The dry-development of 4 μm features was achieved with no appreciable residue. For large area features, a spatially variable exposure method was used to direct the residue away from the exposed area. The gradient exposure method was used to produce 100 μm features. Plasma etching after dry-development was also used to achieve residue-free dry-developed patterns. These results show the benefits of incorporating base additives into a dry-develop depolymerizable resist system and highlight the need for addressing residue formation.
Yi-Wen Lin et al 2024 ECS J. Solid State Sci. Technol.
This study reports a self-induced ferroelectric Ge-doped HfO2 (Ge:HfO2) thin film through interface reactions. In the first experiment, three treatments for forming interfacial layer (IL) were discussed through TiN/2-nm-thick Al2O3/2-nm-thick Ge:HfO2/GeO2/Ge metal-ferroelectric-insulator-semiconductor capacitors. The remnant polarization (Pr), leakage current, and interface trap density (Dit) were compared to select the most appropriate IL treatment. The results show that the in-situ ozone treatment under the standard atomic layer deposition process had the second highest 2Pr value as well as lower Dit values. Next, the thicknesses of Al2O3/Ge:HfO2 would be changed to 4/2 nm and 3/3 nm to investigate the ferroelectricity and leakage current. Although the 3-nm-thick Al2O3/3-nm-thick Ge:HfO2 shows a lower 2Pr value, the leakage current is much lower than 2-nm-thick Al2O3/2-nm-thick Ge:HfO2. The self-induced ferroelectric 3-nm-thick Ge:HfO2 thin film was then applied to fabricate Ge stacked nanowires gate-all-around field-effect transistor. The results show a steep subthreshold slope of 58 mV/dec for pFET and on-off current ratio > 105 and have high potential in low-power IC applications.
Chih-wei Chen et al 2024 ECS J. Solid State Sci. Technol.
This study investigated threshold voltage (VTH) instability in a Schottky p-GaN gate AlGaN/GaN high-electron-mobility transistor (HEMT) by using the double pulse test (DPT) with a 1-µs pulse width in the ON-state and OFF-state. OFF-state drain biases (VDS,OFF) of 100–400 V and ON-state drain currents of ID,ON 1–16 A were applied in the DPT to observe the post-DPT VTH shift. The ON-state currents did not strongly influence the device's characteristics after the DPT. However, the OFF-state voltages, particularly VDS,OFF = 100 and 200 V, exerted notable effects. A TCAD simulation was conducted to investigate the mechanism underlying the VTH shift after the DPT at various VDS,OFF and ID,ON levels.
Hui-Hsuan Li et al 2024 ECS J. Solid State Sci. Technol. 13 055001
We propose a continuous fabrication method for HfO2-based gate stacks on a Ge bulk p-type metal–oxide–semiconductor capacitor (pMOSCAP) with HfGeOx interfacial layer by H2 plasma treatment through in situ plasma-enhanced atomic layer deposition. The electrical characteristics showed that the proper hydrogen plasma treatment could obtain an aggressively scaled equivalent oxide thickness of approximately 0.55 nm and a relatively low gate leakage current of 8 × 10−4 A cm−2 under PMA 500 °C.
William Cheng-Yu Ma et al 2024 ECS J. Solid State Sci. Technol. 13 045003
This work explores the characteristics of ferroelectric thin-film transistors (FeTFTs) utilizing an asymmetric dual-gate (DG) structure in both single-gate (SG) and DG operation modes. In the transfer characteristics, DG mode exhibits a memory window (MW) of 1.075 V, smaller than SG mode's MW of 1.402 V, attributed to the back-gate bias effect causing a reduction in the device's threshold voltage. However, DG mode demonstrates superior endurance characteristics with 106 cycles compared to SG mode's 105 cycles. Additionally, the increase in erase pulse voltage (VERS) exacerbates the polycrystalline-silicon channel lattice damage of FeTFT, resulting in subthreshold swing (SS) degradation. Nevertheless, the extent of SS degradation from DG mode operation is significantly lower than that of SG mode, contributing to the superior endurance of DG mode. The elevation of program pulse voltage (VPRG) induces imprint and charge-trapping effects in the top-gate ferroelectric dielectric, leading to reduced endurance. Due to the use of SiO2 as the back-gate dielectric in FeTFT, DG mode exhibits lower impacts of charge-trapping effects from the top-gate ferroelectric dielectric layer, resulting in better endurance compared to SG mode. The asymmetric DG structure provides greater tolerance in the selection of VPRG and VERS.
Yuga Osada and Takashi Yanagishita 2024 ECS J. Solid State Sci. Technol. 13 043007
Fe substrates with a depression pattern were anodized to obtain Fe oxide films with a nanohoneycomb structure and orderly arranged cylindrical pores of uniform size. Crystalline Fe oxide films could be obtained by the heat treatment of amorphous samples obtained by the anodization of Fe substrates, but the atmosphere during heat treatment had a significant effect on the surface structure and crystallinity of the resulting samples. The heat treatment of the anodized samples in air produced a crystalline Fe oxide film consisting of Fe2O3 and Fe3O4, but the nanohoneycomb structure could not be maintained above 400 °C because the Fe substrate was oxidized during the heat treatment, and its surface structure changed significantly. On the other hand, the heat treatment of the anodized samples in N2 atmosphere yielded Fe3O4 nanohoneycombs, which retained their regular honeycomb structure after heat treatment. The evaluation of the capacitor properties of the heat-treated samples showed that the properties differed markedly owing to the effects of the surface structure and crystallinity, with the sample heat-treated at 400 °C in N2 atmosphere with the largest specific capacitance. The Fe3O4 nanohoneycombs obtained in this study are expected to be useful as electrodes for high-capacity capacitors.
Yoshihiro Irokawa et al 2024 ECS J. Solid State Sci. Technol. 13 045002
Changes in the hydrogen-induced Schottky barrier height (ΦB) of Pt/GaN rectifiers fabricated on free-standing GaN substrates were investigated using current–voltage, capacitance–voltage, impedance spectroscopy, and current–time measurements. Ambient hydrogen lowered the ΦB and reduced the resistance of the semiconductor space–charge region while only weakly affecting the ideality factor, carrier concentration, and capacitance of the semiconductor space–charge region. The changes in the ΦB were reversible; specifically, the decrease in ΦB upon hydrogen exposure occurred quickly, but the recovery was slow. The results also showed that exposure to dry air and/or the application of a reverse bias to the Schottky electrodes accelerated the reversion compared with the case without the applied bias. The former case resulted in fast reversion because of the catalytic effect of Pt. The latter case, by contrast, suggested that hydrogen was incorporated into the Pt/GaN interface oxides as positive mobile charges. Moreover, both exposure to dry air and the application of a reverse bias increased the ΦB of an as-loaded sample from 0.91 to 1.07 eV, revealing that the ΦB of Pt/GaN rectifiers was kept lower as a result of hydrogen incorporation that likely occurred during device processing and/or storage.
Alain E. Kaloyeros and Barry Arkles 2024 ECS J. Solid State Sci. Technol. 13 043001
Silicon carbide (SiCx) thin films deposition processes fall primarily into three main categories: (1) chemical vapor deposition (CVD) and its variants, including plasma enhanced CVD (PE-CVD); (2) physical vapor deposition (PVD), including various forms of sputtering; (3) alternative (non-CVD and non-PVD) methodologies. Part I of this two-part report ECS J. Solid State Sci. Technol., 12, 103001 (2023) examined recent peer-reviewed publications available in the public domain pertaining to the various CVD processes for SiCx thin films and nanostructures, as well as CVD modeling and mechanistic studies. In Part II, we continue our detailed, systematic review of the latest progress in cutting-edge SiCx thin film innovations, focusing on PVD and other non-PVD and non-CVD SiCx coating technologies. Particular attention is given to pertinent experimental details from PVD and alternative (non-CVD and non-PVD) processing methodologies as well as their influence on resulting film properties and performance.
Yajie Zou et al 2024 ECS J. Solid State Sci. Technol. 13 041001
Semiconducting carbon nanotubes (CNTs), characterized by high carrier mobility and atomic thickness, are considered ideal channel materials for building high-performance and ultimate-scale field-effect transistors for future electronics. Here, we present a data-calibrated compact model of CNT field-effect transistors (CNTFETs) that incorporates temperature effects using the virtual source approach. The proposed model also includes the self-heating effect. Temperature effect was characterized by the influence of temperature on devices, achieved through establishing a temperature-dependent semi-empirical model of carrier mobility and carrier velocity. The proposed model can be easily implemented in a simulator. We designed a two-stage operational amplifier (OPAMP) using the proposed model at 32 nm technology. Compared with other studies, the designed CNTFET-based OPAMP demonstrates lower power consumption, which is beneficial for exploring the biological applications of low-power analog circuits in portable electronic devices. Furthermore, the impact of thermal variations on the design of OPAMP, as per the proposed model, was delineated. Investigations revealed that our circuit maintains a high common mode rejection ratio, which diminishes as the temperature increases and exhibits a moderate gain value that escalates with temperature.