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.
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.
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.
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.
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.
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.
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.
F. Nagano et al 2023 ECS J. Solid State Sci. Technol. 12 033002
To obtain reliable 3D stacking, a void-free bonding interface should be obtained during wafer-to-wafer direct bonding. Historically, SiO2 is the most studied dielectric layer for direct bonding applications, and it is reported to form voids at the interface. Recently, SiCN has raised as a new candidate for bonding layer. Further understanding of the mechanism behind void formation at the interface would allow to avoid bonding voids on different dielectrics. In this study, the void formation at the bonding interface was studied for a wafer pair of SiO2 and SiCN deposited by plasma enhanced chemical vapor deposition (PECVD). The presence of voids for SiO2 was confirmed after the post-bond anneal (PBA) at 350 °C by Scanning Acoustic Microscopy. Alternatively, SiCN deposited by PECVD has demonstrated a void-free interface after post bond annealing. To better understand the mechanism of void formation at the SiO2 bonding interface, we used Positron Annihilation Spectroscopy (PAS) to inspect the atomic-level open spaces and Electron Spin Resonance (ESR) to evaluate the dangling bond formation by N2 plasma activation. By correlating these results with previous results, a model for void formation mechanism at the SiO2 and the absence of for SiCN bonding interface is proposed.
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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.
Dinesh M. A. et al 2024 ECS J. Solid State Sci. Technol. 13 053003
This work aims to fabricate a single-feed line Cylindrical Dielectric Resonator Antenna (CDRA) using low-temperature sintered Li3MgNbO5 microwave dielectric ceramic as a resonator, excited in HEM11δ mode. The ceramic synthesized using the conventional solid-state route resulted in a single-phase material exhibiting a cubic structure with an Fm-3m space group. The densely packed cylindrical disk of the ceramic was subsequently characterized for its microwave dielectric behaviour in TE01δ mode using the Hakki-Coleman method. The dielectric permittivity (εr) measures 14.4, with a loss factor (tan δ) nearly equal to 4.01 × 10−4 and a temperature coefficient (τf) of −50.9 ppm °C−1. The antenna design was executed using the high-frequency structure simulator design software, utilizing the dielectric ceramic as the resonator, Cu strip as the feedline, and FR4 as the substrate. The maximum energy was coupled to the antenna when the resonator was placed at 11.75 mm on the substrate. The fabricated CDRA, using appropriate simulated parameters, resonated at 7.67 GHz, offering a return loss (S11) of −32.64 dB and an impedance bandwidth of 10.73%. Furthermore, the CDRA displayed a voltage standing wave ratio of 1.04, ensuring a nearby ideal impedance match and a bandwidth of 810 MHz to support high-speed data transmission.
Haipeng You et al 2024 ECS J. Solid State Sci. Technol. 13 053002
SnSb (SS), a vital phase-change thin film, has attracted attention due to its excellent phase-change properties, but the poor amorphous stability and crystalline speed of SS greatly limit its application in rapid phase-transition memories. Here, we propose a copper (Cu)-doped SS phase change films to achieve ultra-speed and high-reliability of SS. Resistance-temperature tests show Cu-Sn-Sb possesses ultra-low crystalline and amorphous resistivity, higher phase transition speed, and lower activation energy. X-ray diffraction measurements illustrate the introduction of Cu ions hinders the growth of grains and reduce grains size. Atomic force microscopy characterizes the surface morphology of as-deposited and annealed Cu-Sn-Sb films, and difference of root-mean-square roughness before and after annealing promote Cu-Sn-Sb film is more reliable to touch electrodes. In addition, the ultra-low resistivity and fast transition speed effectively reduce thermal loss in SET and RESET process. The results reveal that Cu-Sn-Sb is a promising material for ultra-rapid phase change and high-reliability storage applications.
Akash Ramasamy et al 2024 ECS J. Solid State Sci. Technol. 13 057001
COPD is a respiratory disease with a high mortality rate worldwide. The major cause of death in COPD patients is due to late diagnosis. Early detection of COPD is crucial for significantly reducing the risk of death but is challenging to attain. A distinguished way to early diagnosis is by using the nanosensor for sensing the COPD breath biomarkers. For the first time, we report an armchair silicene nanoribbon (ASiNR) as a promising sensing material for the diagnosis of hexanal a COPD breath biomarker. In this present study, the density functional theory (DFT) with Grimme D2 corrected approach was incorporated to observe the ground state electronic properties and adsorption mechanism of hexanal on the pristine, defect induced (D) and B, C, and N-doped ASiNR systems. N-ASiNR systems show the highest adsorption energy value among previously reported works due to the presence of strong covalent interaction, and it does not show recovery at room temperature. The B-ASiNR system with higher charge transfer exhibits large work function change with the fastest recovery at room temperature in 1.81 s. Our results confirms B-doped ASiNR system acts as an efficient reusable work function-based sensor for the early diagnosis of COPD at room temperature.
Highlights
For the first time adsorption studies of the COPD biomarker hexanal on the ASiNR based materials is reported.
N-doped ASiNR show highest adsorption energy towards hexanal compared to previous works.
B-ASiNR exhibits significant charge transfer through physisorption onto hexanal.
B-doped ASiNR exhibit fastest recovery with substantial change in the work function at room temperature.
Our results confirms that B-ASiNR has the potential to be an effective and reusable sensor.
Yanyan Zhang and Weifeng Sun 2024 ECS J. Solid State Sci. Technol. 13 053001
Various analytical methods were employed to elucidate the effects of filling nano-calcium-silicate or nano-silica on the electronic property, water-uptake, and thermal stability of an amine-crosslinked epoxy (EP) polymer. Molecular-mixture models consisting of a nanofiller or several calcium ions and EP crosslinked macro-molecules were used to simulate local regions of nanofiller/matrix interface or ion-infiltrated matrix, calculating their density of electron-states by first-principles method to determine whether and how the nanofillers introduce charge traps into EP matrix. Calcium cations on nanofiller surface dissociate away from coordinating with silicon-oxygen tetrahedron and infiltrate into void spaces in EP matrix, leaving a larger free volume at filler/matrix interface than in matrix. Calcium cations dissolved in EP matrix are adsorbed in the low electrostatic potential region or coordinate with carbonyl groups in EP matrix and thus introduce a miniband of deep electron traps at energy levels >1 eV lower than conduction band minimum of the amine-crosslinked EP polymer. Even at room temperature, thermal vibrations can break coordinate bonds between calcium cations and silicon-oxygen framework on calcium-silicate nanofiller surface and make considerable calcium ions infiltrating void spaces within EP matrix, leading to comprehensive improvements of cohesive energy, thermal stability, and charge trapping ability in the calcium-silicate/EP nanocomposite.
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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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Lopez Ninantay et al
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.
Praveenkumar et al
Mn-doped Zn3P2-diluted magnetic semiconducting nanoparticles (Zn0.98Mn0.02P2, Zn0.96Mn0.04P2, Zn0.94Mn0.06P2, and Zn0.92Mn0.08P2) were synthesized by a conventional solid-state reaction followed by a subsequent vacuum annealing process. The formation of a tetragonal structure of pure and Mn-doped Zn3P2 was confirmed by X-ray diffraction studies, with no evidence of any further phases. Lattice parameters dicrease from a=b= 8.133 Å, c=11.459 Å to a=b=8.041 Å, c=11.410 Å with increasing dopant concentration. Scanning electron microscpy analysis indicated that all samples that underwent doping exhibited agglomeration in the scanned range of 500 nm. Energy-dispersive X-ray analysis confirmed the presence of Zn, P, and Mn in the samples, and all of the synthesized samples achieved a nearly atomic ratio. In the diffused reflectance spectra, the optical band gap increases from 1.398 to 1.418 eV with increasing dopant concentration. PL has provided evidence indicating that the emission intensity of all doped samples remains constant with increasing dopant content from x=0.02 to 0.08, with different excitation wavelengths (215 and 290 nm). Vibrating sample magnetometer tests confirmed the presence of ferromagnetic behavior at room temperature, and a positive correlation between saturation magnetization and Mn content, with the magnetic moment increasing from 0.0640 to 0.1181 emu/g with an increase in dopant content.
Li et al
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/cm2 and the lowest interface trap density (Dit) of approximately 2 × 1011 eV−1 cm−2 at 500C 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.
Lee et al
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.
Wada et al
To reduce the size of the polisher, especially the polishing head, a novel method for applying the polishing load using magnetic force is proposed. As the fabrication of next-generation power device substrates advances, such as diamond, ultra-precise planarization via chemical mechanical polishing (CMP) becomes crucial for transforming these substrates into functional devices. Achieving CMP necessitates the application of an optimal polishing load to the substrate. Deadweight and air pressure methods are the traditional mechanisms for delivering this load. However, they tend to increase the size and complexity of the polishing head mechanism, hindering its miniaturization. This study proposes leveraging the magnetic force for the application of polishing load. Such an approach not only promises the miniaturization of the polishing head but also paves the way for smaller polishers. We constructed a prototype polisher with a straightforward mechanism and conducted several tests. The removal rate measurements from these tests, when compared with those of the traditional deadweight method in prior research, validated our approach. Additionally, by adjusting the magnet spacing (which adjusts magnetic force) and the rotational speed, we found that the removal rate adheres to Preston’s law even when employing the magnetic force for polishing.
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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.
Jose Lopez Ninantay et al 2024 ECS J. Solid State Sci. Technol.
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.
HuiHsuan Li et al 2024 ECS J. Solid State Sci. Technol.
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/cm2 and the lowest interface trap density (Dit) of approximately 2 × 1011 eV−1 cm−2 at 500C 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.
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.
Chia Feng Hsu et al 2024 ECS J. Solid State Sci. Technol. 13 035004
In the study, the ITO/Cu-doped Fe2O3/ITO thin film RRAM is prepared using an RF sputtering system. The XRD pattern shows that the Cu:Fe2O3 thin film has a rhombohedral structure and does not display secondary or impurity phases for copper. Results revealed that the standard deviation and average voltage of Cu:Fe2O3 thin film are −1.98 and 0.92 V for Vset, respectively, while those for Vreset are 1.31 and 0.39 V, respectively. The resistive switching cycles and data retention test times of the Cu:Fe2O3 thin film device show that the on/off ratio is 39.4 and over 104 s. These results indicated that the Cu-doped Fe2O3 thin film can improve the performance of RRAM.
Jian-Sian Li et al 2024 ECS J. Solid State Sci. Technol. 13 035003
Vertical heterojunction NiO/β n-Ga2O/n+ Ga2O3 rectifiers with 100 μm diameter fabricated on ∼17–18 μm thick drift layers with carrier concentration 8.8 × 1015 cm−3 and employing simple dual-layer PECVD SiNx/SiO2 edge termination demonstrate breakdown voltages (VB) up to 13.5 kV, on-voltage (VON) of ∼2.2 V and on-state resistance RON of 11.1–12 mΩ.cm2. Without edge termination, the maximum VB was 7.9 kV. The average critical breakdown field in heterojunctions was ∼7.4–9.4 MV. cm−1, within the reported theoretical value range from 8–15 MV.cm−1 for β-Ga2O3. For large area (1 mm diameter) heterojunction deives, the maximum VB was 7.2 kV with optimized edge termination and 3.9 kV without edge termination. The associated maximum power figure-of-merit, VB2/RON is 15.2 GW·cm−2 for small area devices and 0.65 GW.cm−2 for large area devices. By sharp contrast, small area Schottky rectifiers concurrently fabricated on the same drift layers had maximum VB of 3.6 kV with edge termination and 2.7 kV without edge termination, but lower VON of 0.71–0.75 V. The average critical breakdown field in these devices was in the range 1.9–2.7 MV. cm−1, showing the importance of both the heterojunction and edge termination. Transmission electron microscopy showed an absence of lattice damage between the PECVD and sputtered films within the device and the underlying epitaxial Ga2O3. The key advances are thicker, lower doped drift layers and optimization of edge termination design and deposition processes.