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
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.
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.
Sean W. King 2015 ECS J. Solid State Sci. Technol. 4 N3029
Over the past decade, the primary focus for improving the performance of nano-electronic metal interconnect structures has been to reduce the impact of resistance-capacitance (RC) delays via utilizing insulating dielectrics with ever lower values of dielectric permittivity. The integration and implementation of such low dielectric constant (i.e. low-k) materials has been fraught with numerous challenges. For intermetal and interlayer (ILD) low-k dielectrics, these challenges have been largely associated to integration with metal interconnect fabrication processes and well documented and reviewed in the literature. Although equally important, less attention has been given to other low-k dielectrics utilized in metal interconnect structures that are commonly referred to as low-k dielectric barriers (DB), etch stops (ES), and/or Cu capping layers (CCL). These materials present numerous challenges as well for integration into metal interconnect fabrication processes. However, they also have more stringent integrated functionality requirements relative to low-k ILD materials that serve only a basic purpose of electrically isolating adjacent metal lines. In this article, we review the integration challenges and associated integrated functionality requirements for low-k DB/ES/CCL materials with a focus on the current status and future direction needed for these materials to facilitate both Moore's law (i.e. More Moore) and More than Moore scaling.
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.
Alain E. Kaloyeros et al 2017 ECS J. Solid State Sci. Technol. 6 P691
This article provides an overview of the state-of-the-art chemistry and processing technologies for silicon nitride and silicon nitride-rich films, i.e., silicon nitride with C inclusion, both in hydrogenated (SiNx:H and SiNx:H(C)) and non-hydrogenated (SiNx and SiNx(C)) forms. The emphasis is on emerging trends and innovations in these SiNx material system technologies, with focus on Si and N source chemistries and thin film growth processes, including their primary effects on resulting film properties. It also illustrates that SiNx and its SiNx(C) derivative are the focus of an ever-growing research and manufacturing interest and that their potential usages are expanding into new technological areas.
Marko J. Tadjer et al 2019 ECS J. Solid State Sci. Technol. 8 Q3187
Gallium oxide (β-Ga2O3) is an emerging semiconductor with relevant properties for power electronics, solar-blind photodetectors, and some sensor applications due to its ultra-wide bandgap and developing technology base for high quality, melt-based substrate growth and thick, low-doped homoepitaxial layers. Of critical importance for the commercialization of this potentially important material is understanding of doping mechanisms in the monoclinic lattice, where two types of Ga sites and three types of O sites have been identified. A critical literature review of doping and defects of the monoclinic β-phase of gallium oxide is provided in this work. Theoretical fundamentals of both donor and acceptor doping in Ga2O3 are reviewed. Advances in doping of epitaxial Ga2O3 with a focus on molecular beam epitaxy and ion implantation are critically examined. As doping is fundamentally related to defects, particularly in this material, a review of defect characterization by optical and electrical spectroscopic methods is provided as well. P-type doping, one of the fundamental challenges for Ga2O3, is discussed in terms of first-principles calculations and ion implantation of known acceptors such as Mg and N.
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.
S. J. Pearton et al 2016 ECS J. Solid State Sci. Technol. 5 Q35
Gallium Nitride based high electron mobility transistors (HEMTs) are attractive for use in high power and high frequency applications, with higher breakdown voltages and two dimensional electron gas (2DEG) density compared to their GaAs counterparts. Specific applications for nitride HEMTs include air, land and satellite based communications and phased array radar. Highly efficient GaN-based blue light emitting diodes (LEDs) employ AlGaN and InGaN alloys with different compositions integrated into heterojunctions and quantum wells. The realization of these blue LEDs has led to white light sources, in which a blue LED is used to excite a phosphor material; light is then emitted in the yellow spectral range, which, combined with the blue light, appears as white. Alternatively, multiple LEDs of red, green and blue can be used together. Both of these technologies are used in high-efficiency white electroluminescent light sources. These light sources are efficient and long-lived and are therefore replacing incandescent and fluorescent lamps for general lighting purposes. Since lighting represents 20–30% of electrical energy consumption, and because GaN white light LEDs require ten times less energy than ordinary light bulbs, the use of efficient blue LEDs leads to significant energy savings. GaN-based devices are more radiation hard than their Si and GaAs counterparts due to the high bond strength in III-nitride materials. The response of GaN to radiation damage is a function of radiation type, dose and energy, as well as the carrier density, impurity content and dislocation density in the GaN. The latter can act as sinks for created defects and parameters such as the carrier removal rate due to trapping of carriers into radiation-induced defects depends on the crystal growth method used to grow the GaN layers. The growth method has a clear effect on radiation response beyond the carrier type and radiation source. We review data on the radiation resistance of AlGaN/GaN and InAlN/GaN HEMTs and GaN–based LEDs to different types of ionizing radiation, and discuss ion stopping mechanisms. The primary energy levels introduced by different forms of radiation, carrier removal rates and role of existing defects in GaN are discussed. The carrier removal rates are a function of initial carrier concentration and dose but not of dose rate or hydrogen concentration in the nitride material grown by Metal Organic Chemical Vapor Deposition. Proton and electron irradiation damage in HEMTs creates positive threshold voltage shifts due to a decrease in the two dimensional electron gas concentration resulting from electron trapping at defect sites, as well as a decrease in carrier mobility and degradation of drain current and transconductance. State-of-art simulators now provide accurate predictions for the observed changes in radiation-damaged HEMT performance. Neutron irradiation creates more extended damage regions and at high doses leads to Fermi level pinning while 60Co γ-ray irradiation leads to much smaller changes in HEMT drain current relative to the other forms of radiation. In InGaN/GaN blue LEDs irradiated with protons at fluences near 1014 cm−2 or electrons at fluences near 1016 cm−2, both current-voltage and light output-current characteristics are degraded with increasing proton dose. The optical performance of the LEDs is more sensitive to the proton or electron irradiation than that of the corresponding electrical performances.
Latest articles
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I. M. El Radaf and H. Y. S. Al-Zahrani 2024 ECS J. Solid State Sci. Technol. 13 035002
The present study used chemical deposition to deposit thin copper aluminum tin sulfide (CATS4) layers onto clean glass substrates. X-ray diffraction analysis was utilized to explore the crystalline structure of the CATS4 films, which refers to the CATS4 films having a cubic crystal structure. Energy-dispersive X-ray analysis showed the presence of Cu, Al, Sn, and S peaks in the CATS4 films, and their atomic ratio is close to 1:1:1:4. Spectrophotometric measurements of optical transmittance and reflectance spanning the 400–2500 nm spectral range were performed to describe the optical properties of the CATS4 layers. The CATS4 films demonstrated a direct energy gap transition between 1.42 and 1.31 eV. Further, increasing the layer thickness enhanced the refractive index and Urbach energy of the CATS4 films. The inspected CATS4 films showed better optoelectrical properties with increasing thickness, including improved optical conductivity, optical resistivity, optical carrier concentration, relaxation time, and optical mobility. Increasing the thickness of the CATS4 films increased their nonlinear optical indices. Additionally, the hot probe apparatus verified the p-type semiconducting characteristics of CATS4 films.
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.
Paweł E. Tomaszewski 2024 ECS J. Solid State Sci. Technol. 13 030001
It is obvious and well known that, when starting studies on a given sample, it is necessary to be sure of the chemical and phase composition of the sample. The most ideal method is to verify this by X-ray (or neutron) diffraction and subsequent structural analysis. Such initial analysis must use the well-known set of assumptions based on 100 years of X-ray diffraction studies. Without the use of these assumptions or rules, the subsequent results of any studies will not be valuable and may be erroneous. The most important rule is that the diffraction pattern is a kind of fingerprint of the given crystal/compound. Thus, the second rule is that the diffraction pattern of the mixture of phases is a simple sum of diffraction patters from the components.
Anand Sharma et al 2024 ECS J. Solid State Sci. Technol. 13 037008
In the current study, the magnetic nanoparticles of neodymium and samarium substituted Mg-Zn-Cu, with a chemical composition of Mg0.5Zn0.5Cu0.05RxFe1.95-xO4 (x = 0.05; R = Nd, Sm) were produced via the sol-gel auto-combustion route. XRD indicates the evolution of a cubic symmetry having Fd3m space group and no impurities at the room temperature. The FESEM images show the irregularly shaped and agglomerated grains in all samples. FTIR examination reveals the stretching vibrations among the metal cations and anions at interstitial vacancies. The M-H graphs demonstrates that the prepared nanoferrites have low rentivity (0.18–0.84 emu g−1) and coercivity (11.25–34.03 Oe) indicating the formation of superparamagnetic nature. From the electromagnetic traits, the observed sample's real magnetic permeability (μ'') and permittivity (ε') along with dielectric loss and magnetic loss reduced with increasing applied field frequency, indicating the typical behaviour of spinel nanoferrites. This may be explained by Maxwell-Wagner interfacial polarisation and the electron hopping among the ferrous and ferric ions. The variations in coercivity, anisotropy constant, and electromagnetic traits provide strong evidence that all of the samples are thermally stable and have the potential to be used in solenoids and transformers, and also, in the more resistive devices that operate at the high frequency.
Hudabia Murtaza et al 2024 ECS J. Solid State Sci. Technol. 13 033006
Cs-based perovskites hold immense significance in the field of green technology due to their unique properties, offering promising avenues for efficient, low-cost devices. In this theoretical work, DFT has been employed to extensively scrutinize the physical properties of double fluoroperovskites Cs2TlAgF6. The modified Becke Johnson functional was used to take exchange-correlation effects into consideration accurately. From the calculated value of formation energy, volume optimization curve, Goldsmith tolerance factor and octahedral tilting, the structural stability is demonstrated. The band structure of Cs2TlAgF6 depicts a direct bandgap of 2.21 eV, proving its semiconducting nature. This study also assessed the mechanical properties in detail, showing the ductile character of Cs2TlAgF6. A thorough examination of optical characteristics reveals the potential application in a variety of photovoltaic devices due to its strong absorption in visible region. The transport attributes are accessed through large ZT value and other thermal parameters. With its exceptional heat-to-electricity conversion properties, this material shows promise for applications in thermoelectric devices, offering a sustainable way to generate electricity from waste heat. The larger value 0.788 of ZT depicts that material exhibit sufficient potential for generating energy from waste heat.
Review articles
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Paritosh Chamola et al 2024 ECS J. Solid State Sci. Technol. 13 035001
This review is focused on the current development in domain of organic photovoltaic cells (OPVs). Solar cells play a vital role for electricity production by converting sunlight to electric current. This paper presents an exhaustive literature review on advancements in field of OPVs. The solar cells, as a substitute for fossil fuels are, at the forefront in a wide range of research applications. The organic solar cells efficiency and operational lifespan made outstanding advancement by refining materials of the photoactive layer and presenting new inter-layers. The functioning of organic solar cells is centered on photoinduced electron transfer. Organic solar cell technology has immense potential owing to lower production cost and flexible characteristics. The latest advancement in the material engineering and sophisticated device structure have significantly improved the solar cells commercial feasibility. Further, we highlight the research and advancements of organic bioelectronics in powering numerous bio-medical electronic devices. The important challenges, engineering result, and forthcoming prospects driving the progress of OSCs are explored.
Subramani Supriya 2024 ECS J. Solid State Sci. Technol. 13 013012
The invention of yttrium titanates (Y2Ti2O7) with various exciting properties in electroceramics has created great attention among industrialists and researchers. Improving the materials of pyrochlore oxides with significant properties for future electronic devices became essential. The Y2Ti2O7 is one such cubic pyrochlore at room temperature, having excellent dielectric and luminescence properties. This article comprehensively reviews the basics and state-of-the-art in developing Y2Ti2O7 ceramics. This material is widely used for electronic devices: transducers, capacitors, optoelectronic components, and light modulators. This review focuses on the fabrication methods and crystal structure mechanisms for optimizing functional properties and current challenges. Moreover, the effect of doping elements of Y2Ti2O7-based ceramics is briefly discussed. Also, future perspectives are provided to spotlight new and trending research directions in this materials research.
Hussain J. Alathlawi and K. F. Hassan 2024 ECS J. Solid State Sci. Technol. 13 011002
Lithium-ion batteries (LIBs) are highly promising energy storage devices because they provide high power output and an extended cycling lifespan, resulting in a unified and efficient system. However, the current lithium-ion batteries have limitations in providing high energy density due to the slow spread of Li+ ions and the low electrical conductivity of the anode and cathode materials. This trade-off results in a situation where the power is concentrated rather than the energy. Furthermore, the significant disparities in capacity and kinetics between the anode and cathode lead to subpar rate performance and inadequate cycling stability. Hence, the development of anode materials with high power capability and structural stability holds immense importance in the context of practical LIBs. Graphene-based materials have been extensively analyzed as cathode materials in LIBs due to their distinctive structure and exceptional electrochemical characteristics. Noteworthy progress has been achieved in this field. This article summarizes recent advances in graphene-based anodes and cathodes for lithium-ion batteries. The paper concludes by analyzing current obstacles and providing recommendations for future research.
Highlights
Lithium-ion batteries (LIBs) are widely regarded as promising energy storage devices due to their ability to give high power output
Graphene-based materials have been extensively investigated as anode and cathode materials in LIBs
This article comprehensively summarizes the current advancements in graphene-based anode and cathode materials for lithium-ion batteries.
Samiya Fariha et al 2023 ECS J. Solid State Sci. Technol. 12 121005
PVC (polyvinyl chloride) is a thermoplastic polymer used extensively in industrial applications. The potentiality of PVC lies in various parameters, such as high tensile strength, biodegradability, large surface area, chemical stability, low weight, durability, cost-effectiveness, and availability. However, the low thermal stability and brittleness of pure PVC limit its acceptance in widespread applications. Therefore, modifying PVC with metal oxides and carbon nanofillers could substantially improve thermal stability, mechanical strength, biocompatibility, surface area, conductivity, etc. Enhanced properties in modified PVC result from the chemical and physical interaction between polymer and functionalized nanofillers and the good dispersion capability of nanofillers on polymer matrix, which is attributed to the excellent performances of nanocomposites in diverse fields. This paper aims to present an overview of the characterization, preparation, and applications of blend nanocomposites of PVC, which would benefit future developments in this field.
Sadao Adachi 2023 ECS J. Solid State Sci. Technol. 12 126003
The purpose of this review article is to present and clarify the various phosphor properties of Mn2+ activator ion in the intra-3d5-shell electronic configuration. Even though the concepts of intra-3d5-shell electronic configuration in Mn2+ ion are well understood at this time, some important properties of this ion in the various host materials have been hampered by a lack of definite knowledge of such phosphor systems. The Mn2+-activated phosphor properties examined in the present article can be classified into seven groups: (1) spectral feature of Mn2+-ion photoluminescence (PL) and PL excitation (PLE) transitions, (2) temperature dependence of PL intensity, (3) temperature dependence of PL decay lifetime, (4) Mn2+ concentration effects on PL properties, (5) excitonic transition-related Mn2+ luminescence, (6) crystalline morphology effects: bulk sample vs microcrystalline sample, and (7) crystalline morphology effects: quantum confinement-induced phenomena. Key expressions for theoretically analyzing PL and PLE spectral features, together with PL intensity variation with temperature, for the Mn2+ emission were discussed in detail. A detailed discussion is also given of the acceptability of such phosphor properties and behaviors from an applicational point of view.
Editor's Choice
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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.
M. S. Shur et al 2023 ECS J. Solid State Sci. Technol. 12 035008
Novel metal oxide materials such as InGaZnO (IGZO), ZnO, SnO, and In2O3 and improved fabrication processes dramatically enhanced the achieved and projected thin film transistor (TFT) performance. The record values of the effective field-effect mobility of Metal Oxide TFT (MOTFT) materials have approached 150 cm2/Vs. We report on an improved compact TFT model based on three models: the RPI TFT model, the unified charge control model (UCCM), and the multi-segment TFT compact model. This improved model accounts for a non-exponential slope in the subthreshold regime by introducing a varying subthreshold slope and accounts for non-trivial capacitance dependence on the gate bias, and parasitic impedances. The analysis of the TFT response using this model and the analytical calculations showed that TFTs could have a significant response to impinging THz and sub-THz radiation. Using a complementary inverter and the phase-matched THz signal feeding significantly improves the detection sensitivity.
Accepted manuscripts
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Fang et al
In the localized and global chemical mechanical planarization (CMP) process of Co barrier layers, corrosion inhibitors play a crucial role in the removal rate (RR) of Co and the post-polishing surface quality. In this study, quantum chemical calculations were employed to investigate the molecular reactivity of benzotriazole (BTA), 5-methyl benzotriazole (TTA), and 2,2'-{[(methyl-1H-benzotriazol-1-yl)methyl]imino}bis-ethanol (TT-LYK), and their inhibitory performance was predicted to follow the order of TT-LYK > TTA > BTA. The experimental results validated the accuracy of the predicted order under static conditions. However, the performance order of the inhibitors shifted to TTA > BTA > TT-LYK due to varying degrees of damage caused by mechanical friction to the inhibitory film. Nevertheless, all three inhibitors are capable of effectively inhibiting the Co RR to meet industrial requirements. Ultimately, considering the outstanding inhibitory performance of TT-LYK and its ease of removal during post-cleaning processes, TT-LYK is determined as the most promising inhibitor for Co barrier layer CMP.
Shimizu et al
Ge has many unique characteristics, such as high carrier mobility and a narrow bandgap corresponding to near-infrared wavelengths. To take advantage of the attractive characteristics of Ge, Ge-on-Insulator (GOI) structures are necessary. In this study, we focus on a direct wafer bonding and etchback method to fabricate GOI structures and explore appropriate etching solutions for the etchback. An HF + H2O2 + CH3COOH solution can isotropically etch Ge and improve surface uniformity. The resulting surfaces were sufficiently flat to achieve Schottky and MOS diodes showing good electrical characteristics of the same level as devices based on commercial mirror-polished Ge surfaces. We discuss the role of the chemicals in the etching solution in achieving the flat surface. We fabricated GOI structures and a back-gate GOI capacitor through direct wafer bonding of SiO2/Si and Al2O3/Ge with the etchback method using the solution. The resulting electrical characteristics are also explained using theoretical calculations. This approach might offer an alternative route to high-quality GOI fabrication.
Hang et al
As a typical multi-functional soft-brittle ceramics material, lithium tantalate (LT) exhibits excellent electro-optical and ferroelectric properties and has now been widely applied in many fields, such as electro-optical modulators, pyroelectric detectors, and surface acoustic wave substrates. Traditional free-abrasive polishing processing of lithium tantalite crystals is generally fraught with poor efficiency for its lower fracture toughness. This study proposed a method of polishing lithium tantalite wafer by means of fixed-abrasive plates. A cutting force model and the relative cutting speed model of the machining mechanism of fixed-abrasive plates were first established, and then the main influencing factors of cutting force and relative cutting speed were analyzed on the basis of the theoretical model. It was found that cutting force is influenced by eccentricity and load, while relative cutting speed is influenced by eccentricity and the fixed-abrasive plates' rotation speed. Finally, single-factor tests were conducted on these influencing factors, and the comparative analysis between the experimental results and those in the theoretical model shows that they are highly correlated to each other. After 30 minutes of polishing under the optimized parameters w=60rpm, e=90mm, variable load, the surface roughness Sa of the workpiece is reduced to 1.234 nm, and the MRR reaches 14.821 μm/h.
K C et al
The growing demand for sustainable and environmentally-friendly technologies has spurred the exploration of innovative methods for waste management and resource utilization. Among the various bio-wastes generated globally, watermelon peel emerges as a significant contributor. To characterize carbon materials in the presence of functional groups, for morphological analysis, and intensity, we subjected activated fruit peel carbon to X-ray diffraction, Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy, X-ray photoelectron spectroscopy, and Raman studies. Furthermore, we examined its electrochemical performance. Another method used to assess wettability is the contact angle. Watermelon-rind-activated carbon was exposed to a DC glow discharge oxygen and air plasma with a 450V applied potential. The air-treated carbon demonstrated a noteworthy capacitance of 1669F/g at 0.5mA/g in a 2M KOH electrolyte. Our study found that the properties of the activated carbon were enhanced through cold plasma treatment. This research provides valuable insights into the potential resources of fruit peels and proposes a novel adsorbent with cost-effective advantages in supercapacitors, which could provide effective energy storage for portable gadgets, electric cars, and renewable energy systems, thus presenting a solution for sustainable waste management.
Mohammed et al
YFeO3 (YFO) and optimized glass wt% [0.5Li2O-0.5K2O-2B2O3 (LKBO) and BaO-Bi2O3-B2O3 (BBBO)] as a sintering aid in YFO ceramics were fabricated using fine powders prepared from sol-gel technique. Pure YFO and glass sintering aid added into YFO ceramics show orthorhombic crystal structure, confirmed by Rietveld refinement with the help of X-ray powder diffraction data. Scanning electron microscopy study revealed that the glass sintering aid added into YFO ceramics shows a higher average grain size than that of YFO ceramic. X-ray photoelectron spectroscopy was employed to confirm the presence of each atom/ion/element and their oxidation number in their respective samples. Using the Archimedes method, the density of the each ceramic sample was estimated. The BBBO glass sintering aid added into YFO exhibited a higher maximum magnetization value (2.82 emu/g) compared to that of LKBO added into YFO (2.51 emu/g) as well as pure YFO (1.53 emu/g) ceramics. BBBO glass sintering aid added into YFO ceramic shows a higher dielectric constant, lower dielectric loss, and lower conductivity compared to LKBO added into YFO as well as pure YFO ceramics. In conclusion, improved magnetic and dielectric response of BBBO glasses added into YFO ceramic is a potential candidate for different dielectric-magnetic based applications.
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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.
Yajie Zou et al 2024 ECS J. Solid State Sci. Technol.
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.
Koji Kobayashi et al 2024 ECS J. Solid State Sci. Technol. 13 033004
Technology computer-aided design (TCAD) kinetic Monte Carlo simulations revealed the unique recrystallization processes of discrete amorphous regions connected to a buried amorphous layer in a C3H5-molecular-ion-implanted silicon (Si) substrate. The faithful simulation models show that the discrete amorphous regions are first recrystallized two-dimensionally in the lateral direction from both sides and separated from the buried amorphous layer. Then, the separated discrete amorphous regions are recrystallized three-dimensionally in the lateral and vertical directions from both sides and the bottom. We found that the first two-dimensional recrystallization of discrete amorphous regions is caused by the retardation of solid-phase epitaxial growth at the Si substrate surface and near the buried amorphous layer. We also found that the large (small) discrete amorphous regions require a long (short) two-dimensional recrystallization before separating from the buried amorphous layer. The transition point in the recrystallization dimension can be determined from the lateral recrystallization length and the equivalent radius of discrete amorphous regions.
Chia Feng Hsu et al 2024 ECS J. Solid State Sci. Technol.
ITO/Cu-doped Fe2O3/ITO thin film resistive random access memory (RRAM) was prepared using a radio-frequency (RF) sputtering system. X-ray diffraction patterns show 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.
Liqun Zhao et al 2024 ECS J. Solid State Sci. Technol. 13 021004
Electromagnetic wave (EMW) absorbers and electromagnetic shielding materials have attracted much attention in recent years. In this paper, Ni/wood-based porous carbon (WPC) composite material was prepared via morphology genetic method by using nickel chloride and poplar as raw material, The experimental results show that the microwave absorbing properties of the materials are related to the pyrolysis temperature, when the pyrolysis temperature settle at 700 °C, the minimum reflection loss of WPC-Ni can reach-60.4 dB with the thickness of 2.93 mm. Moreover, the effective absorption bandwidth has been greatly broadened up to 7.3 GHz when the thickness is 2.63 mm. The reason for such excellent wave absorbing performance is that the introduction of magnetic particles Ni and WPC-Ni regular straight channels improve impedance matching, the heterogeneous interface of Ni/ wood increases the polarization loss of electromagnetic waves. It is believed that this work can provide a new idea for the preparation of low-cost and high-efficiency broadband microwave absorber.
Highlights
A simple and easy method to prepare Ni/ wood composite hierarchically porous structure materials.
The minimum reflection loss value reaches −60.4 dB with the thickness of 2.93 mm, and the effective absorption bandwidth is 7.3 GHz when the thickness is 2.63 mm.
A unique three-dimensional pore structure combined with the waveguide theory, the electromagnetic wave can reflect the loss many times in the channel, which improves the microwave absorbing performance of the material.
Md Hafijur Rahman et al 2024 ECS J. Solid State Sci. Technol. 13 025003
Thermal annealing is commonly used in fabrication processing and/or performance enhancement of electronic and opto-electronic devices. In this study, we investigate an alternative approach, where high current density pulses are used instead of high temperature. The basic premise is that the electron wind force, resulting from the momentum loss of high-energy electrons at defect sites, is capable of mobilizing internal defects. The proposed technique is demonstrated on commercially available optoelectronic devices with two different initial conditions. The first study involved a thermally degraded edge-emitting laser diode. About 90% of the resulting increase in forward current was mitigated by the proposed annealing technique where very low duty cycle was used to suppress any temperature rise. The second study was more challenging, where a pristine vertical-cavity surface-emitting laser (VCSEL) was subjected to similar processing to see if the technique can enhance performance. Encouragingly, this treatment yielded a notable improvement of over 20% in the forward current. These findings underscore the potential of electropulsing as an efficient in-operando technique for damage recovery and performance enhancement in optoelectronic devices.
Zhen-Jin Wang et al 2024 ECS J. Solid State Sci. Technol. 13 026003
This study investigates the effects of TMAH treatment on 5 μm-sized GaN-based Micro LEDs. Compared with untreated GaN Micro LEDs, the optical output power and external quantum efficiency of TMAH treated Micro LEDs are significantly improved. These results can be attributed to the formation of microstructures on the sidewall of Micro LEDs through the TMAH treatment and the effective light reflection is therefore constructed. This research not only improves the characteristics of LEDs, but also paves the way for green and advanced optoelectronic devices.
Seung-Hyun Mun et al 2024 ECS J. Solid State Sci. Technol. 13 026002
This study presents a comprehensive investigation into the optimization of AlGaInP-based red micro-light emitting diodes (LEDs) by implementing double dielectric passivation layers. We employed a two-step passivation process that combined atomic layer deposition (ALD) for a thin Al2O3 layer and plasma-enhanced chemical vapor deposition (PECVD) for a thicker dielectric layer to passivate the sidewalls of the LEDs. After double-passivation, the devices exhibited significantly reduced leakage current compared with their non-passivated counterparts. Notably, the passivated LEDs consistently demonstrated lower ideality factors across all size variations. The Al2O3-SiNx passivated devices exhibited a remarkable 38% increase in optical power at a current density of 1000 A cm−2, along with a noteworthy 41% improvement in the external quantum efficiency (EQE) at a current density of 7 A cm−2 compared to the reference devices. In addressing the challenge of efficiency degradation in AlGaInP-based red micro-LEDs, this study underscores the effectiveness of dual dielectric passivation, emphasizing the superiority of Al2O3-SiNx as a passivation material. These findings hold promise for micro-LED technology and microdisplays, particularly in applications such as augmented reality by significantly enhancing electrical and optical performance.
S. Endo et al 2024 ECS J. Solid State Sci. Technol. 13 023005
A sputtering method is used to form the seed layer for copper electric plating. In general, copper sputtering has weak adhesion to resin, so titanium sputter is combined to increase the adhesion strength. However, etching in the lithography process requires two types of processes, titanium and copper metal. Adhesion strength was improved by performing vacuum ultraviolet (VUV) treatment as a pretreatment for medium-vacuum sputtering. We discovered the relationship between the hydroxyl groups on the resin surface and the adhesion strength by the chemical modification XPS method. Furthermore, by XPS analysis of the peeled copper interface, the adhesion mechanism between the resin and copper due to VUV irradiation was estimated. We evaluated the absorption properties in the vacuum ultraviolet region of a thinly polished glass epoxy resin. We investigated the behavior of functional groups at the interface and considered the effect of vacuum ultraviolet light in the depth direction.
Haruka Itoh and Takashi Yanagishita 2024 ECS J. Solid State Sci. Technol. 13 023002
Anodic porous alumina (APA) membranes with a high density of uniformly sized pores are promising materials for microfiltration. However, such membranes obtained by anodizing Al are amorphous, chemically less stable, and cannot be used to filter acidic or basic solutions. The chemical stability of APA membranes can be improved by heat treatment at temperatures above 1000 °C, resulting in membrane filters with excellent chemical stabilities. However, such a high-temperature treatment makes APA membranes brittle owing to alumina crystallization, which reduces their mechanical strength and makes them less durable. In this study, a membrane filter with both chemical resistance and mechanical strength was fabricated by coating an APA membrane with a TiO2 layer by atomic layer deposition (ALD). The resulting membrane filters showed improved chemical stability in acidic and basic solutions because the TiO2 layer coated on the surface of the APA membrane protected the membrane against its dissolution. In addition, the resulting TiO2-coated APA membrane retained its high mechanical strength, as the membrane itself was not exposed to high-temperature conditions during TiO2 coating by ALD, and the crystallization of the alumina layer did not proceed. The obtained TiO2-coated APA membranes are promising as microfiltration membranes applicable to acidic and basic solutions.