Stable Si Research Articles

Controllable SiOx Coating Layer Promotes High Stable Si Anode for Lithium-Ion Batteries.

Silicon (Si) is considered as one of the most promising candidates for next-generation lithium-ion batteries with high energy density. The main problems are the severe volume expansion and continuous interfacial side reaction of Si that hinder its further application. It can be an effective way by constructing a robust coating layer outside of Si to impede/alleviate the above effect. SiOx with high mechanical strength can largely promote the electrochemical performance of Si. Herein, Si@SiOx material with high specific surface area, high porosity, and controllable coating was synthesized via a simple solid-liquid reaction by LiOH solution etching effect. The etching/oxidation mechanism of Si under alkaline conditions was thoroughly investigated. The surface oxide layer of Si was beneficial to the formation of a solid electrolyte interphase (SEI) with excellent stability and high Li+ conductivity, while its high-porosity structure reduces the volume expansion of the material by approximately 110%. Under the synergistic effect of etching-oxidation, the modified material exhibited superior electrochemical properties. When employed as anode materials, the specific capacity was as high as 3101.5 mAh g-1 and maintained at 841.0 mAh g-1 after 500 cycles at 1 A g-1.

Heritage research at the PUMA beamline

The PUMA beamline, created for the heritage community and accessible by all fields of science, welcomed its first users in 2019. Its optical layout uses a horizontal focusing mirror to prefocus the light emitted from the wiggler source for the experimental endstation. It provides a 5 µm × 7 µm microbeam for XRF, XAS, XRD and XEOL analysis or a wide 20 × 5 mm full field when the beam is defocused, and the KB mirrors are retracted. An extremely stable fixed-exit Si(111) monochromator is used to select the wavelength. Many experiments have been performed at PUMA, particularly in archaeology, paleontology, conservation, art history and in identifying safer conditions of irradiation for precious heritage samples. XRF analysis has been used, for example, to show the effects of the interaction of Palaeolithic ivory with soil; to identify the elemental composition of mineralized textiles and to reveal hidden morphologies of fossils.

An Investigation into the Viability of Portable Proximal Sensor X-Ray Fluorescence Data for Assessing Heavy Metal Contamination in Urban Soils: A Case Study in Changchun, China.

In order to validate the applicability of pXRF for rapid in situ detection of heavy metals in urban soils and to accurately obtain an assessment of soil quality in Changchun, a city in northeast China, 164 soil samples from within the main urban area of Changchun were collected for pXRF analysis. The main stable elements Si and Ti were used to establish a matrix effect correction model, and the values of Cr (64.2 mg⋅kg-1), Cu (43.8 mg⋅kg-1), Zn (96.2 mg⋅kg-1), As (20.9 mg⋅kg-1), and Pb (57.4 mg⋅kg-1) were predicted. The empirical findings indicate that the quality of soil data from the pXRF was improved to different degrees under the correction model, and it became a relatively reliable dataset; the order of improvement was Cu > Pb > Cr > Zn > As. A comprehensive assessment indicated that Changchun City is primarily contaminated by the heavy metals As, Pb, and Cu, with the main sources being automobile manufacturing and pharmaceutical chemical production. These findings align with previous studies and have produced favorable outcomes in practical applications. This rapid, non-destructive and economical detection method is very applicable and economical for the sustainable monitoring and control of heavy metals in large cities. This study provides a basis for rapid large-scale prediction of urban soil safety and protection of local human health.

Unraveling Morphology and Chemistry Dynamics in Fluoroethylene Carbonate Generated Silicon Anode Solid Electrolyte Interphase across Delithiated and Lithiated States

The silicon (Si) solid electrolyte interphase (SEI) faces cyclical cracking and reconstruction due to the ~350% volume expansion. Understanding the SEI dynamic morphology and chemistry evolution from delithiated to lithiated states is thereby paramount to engineering a stable Si anode. Fluoroethylene carbonate (FEC) is a preferred additive with widely demonstrated enhancement of the Si cycling. Thus, insights into the dynamics of the FEC-SEI may provide hints toward engineering the Si interface. Herein, complementary ATR-FTIR, AFM, tip IR, and XPS probing reveal the presence of an elastomeric polycarbonate-like matrix in the FEC-generated SEI which is absent from the FEC-free SEI. Adding FEC to the baseline 1 M LiPF6 in EC:EMC (1:1) electrolyte promotes formation of a thinner and more conformal SEI, and subdues morphology and chemistry changes between consecutive half-cycles. From AFM, morphological stabilization of the FEC-SEI occurs earlier. Furthermore, conventional SEI biproducts such as Li2CO3 and LiEDC appear in reduced quantities in the FEC-SEI implying a reduced quantity of Li-consuming species. The thin polymeric FEC-SEI enables deeper (de)lithiation of silicon. In conclusion, the enhanced mechanical compliance, chemical invariance, and reduced Li inventory consumption of the FEC-SEI are logically the key features underlying the Si cycling enhancement by FEC.

Both the ionic and covalent bonds stabilize the W@Si12 cluster

Si is an important semiconductor material in the development of modern industry. With the miniaturization trend of semiconductor devices, the size of Si has reached the cluster size. The search for stable Si clusters is an important issue. In this work, the electronic structures and stability mechanism of the W@Si12 cluster are calculated by the first-principle calculations. Different from a C2v hexacapped trigonal prism structure of Si12, the W@Si12 cluster presents an embedded hexagonal prism structure with D6h symmetry. The addition of W atom leads to a higher stability. The molecular orbitals show obvious superatomic characteristics for the W@Si12 cluster, and their energy levels are more degenerate than that of the Si12 cluster. The population analysis indicates that a total charge of 2.21e is transferred from Si atoms to the center W atom, which suggests an ionic bond for W-Si. The electron localization function further proves a covalent bond for Si–Si. The enhanced stability of the W@Si12 cluster is attributed to the combination of the ionic and covalent bonds.

Fabrication of 197Au-backed Silicon target for In-beam Gamma-ray spectroscopy experiment

The fabrication of stable 197Au-backed natural Si targets with a thickness ranging from ∼ 400 μg/cm2 to ∼ 1.1 mg/cm2 using an electron beam evaporation technique is discussed. In one of the attempts, a graphite sheet was used as an evaporation source, which proves to be an efficient method in terms of minimal wastage of source material. Characterizations of the fabricated targets using various technique revealed that the targets were uniform in thickness and had negligible contamination. The optimization of evaporation parameters in the present work enhances the potential for future fabrication of isotopically enriched Si targets.

Unraveling Morphology and Chemistry Dynamics in Fluoroethylene Carbonate Generated Silicon Anode Solid Electrolyte Interphase Across Delithiated and Lithiated States: Relative Cycling Stability Enabled by an Elastomeric Polymer Matrix

The silicon solid electrolyte interphase (SEI) faces cyclical cracking and reconstruction due to the ∼350% volume expansion. Understanding the SEI dynamic morphology and chemistry evolution from delithiated to lithiated states is thereby paramount to engineering a stable Si anode. Fluoroethylene carbonate (FEC) is a preferred additive with widely demonstrated enhancement of the Si cycling. Thus, insights into the dynamics of the FEC-SEI may provide hints toward engineering the Si interface. Herein, complementary ATR-FTIR, AFM, tip IR, and XPS probing reveal the presence of an elastomeric polycarbonate-like matrix in the FEC-generated SEI which is absent from the FEC-free SEI. Adding FEC to the baseline 1 M LiPF6 in EC:EMC (1:1) electrolyte promotes formation of a thinner and more conformal SEI, and subdues morphology and chemistry changes between consecutive half-cycles. From AFM, morphological stabilization of the FEC-SEI occurs earlier. Furthermore, conventional SEI biproducts such as Li2CO3 and LiEDC appear in reduced quantities in the FEC-SEI implying a reduced quantity of Li-consuming species. The thin polymeric FEC-SEI enables deeper (de)lithiation of silicon. In conclusion, the enhanced mechanical compliance, chemical invariance, and reduced Li inventory consumption of the FEC-SEI are logically the key features underlying the Si cycling enhancement by FEC.

Atypical Seasonality of the Silicon Cycle in the Yellow River Estuary and Bohai Sea Revealed by Stable Silicon Isotopes

AbstractBiogeochemical Si cycle in coastal areas is of vital importance due to its close link with the carbon cycle. However, the coastal Si cycle has been heavily perturbated by human activities. In this study, we studied the spatiotemporal distribution of biogenic Si (BSi) and dissolved Si (DSi) combined with stable Si isotopes of DSi (δ30SiDSi) in the Yellow River estuary and Bohai Sea, one of the most populated coastal areas in the world. Over an annual cycle, BSi and DSi concentrations varied from 0 to 43.5 μmol L−1 and from 0.3 to 40 μmol L−1, respectively. This was associated with large δ30SiDSi variations from +0.49 ± 0.22‰ (2sd) in spring to +2.92 ± 0.14‰ in winter, which opposed to observations that summer δ30SiDSi values were usually higher than those in winter. This atypical variation could be attributed to the water‐sediment regulation on the Yellow River occurring every early summer, leading to a strong water mixing pattern and suppressing diatom production in summer. This mixing was further prolonged by extreme autumn rainfall on land. The pulse supply of nutrients subsequently enhanced primary productivity from autumn through winter. In spring, the resuspended seafloor sediments were likely an important DSi source with δ30Si values of <−0.5‰. Our findings suggest that natural Si seasonality has been greatly masked by human activities and climate events in the Bohai Sea. Our study serves as a reference of the Si cycle research endeavors worldwide for revealing the overlaying effect of anthropogenic consequences and natural variability.

Enabling stable high-performance CoO-assisted Si@C anode via ball milling strategy

Developing sustainable and simple preparation methods of Si/C composites for lithium-ion battery anodes that are capable of delivering high performance is essential, but remains a challenge. In this work, a sustainable and simple ball milling coupled with carbonization method is developed to construct an advanced Si@Co@C composite anode with a characteristic structure. The structure-property correlations of Si@Co@C in lithium storage are studied by density functional theory (DFT) calculations and ex-situ characterization techniques such as XPS, XRD and TEM. The findings show that CoO assisting, porous carbon coating and LiF-rich SEI layer together make Si@Co@C exhibit improved lithiation/delithiation kinetics and structure durability during cycle and hence outstanding electrochemical performance with 1248.5, 927.0 and 591.5 mAh g−1 at 100, 1000 and 3000 mA g−1 after 400 cycles, respectively. Impressive performance is also observed in the full battery test of Si@Co@C. Finally, this work offers meaningful reference for developing advanced Si/C anode through a facile method.

Constructing a Stable Integrated Silicon Electrode with Efficient Lithium Storage Performance through Multidimensional Structural Design.

Silicon (Si) stands out as a highly promising anode material for next-generation lithium-ion batteries. However, its low intrinsic conductivity and the severe volume changes during the lithiation/delithiation process adversely affect cycling stability and hinder commercial viability. Rational design of electrode architecture to enhance charge transfer and optimize stress distribution of Si is a transformative way to enhance cycling stability, which still remains a great challenge. In this work, we fabricated a stable integrated Si electrode by combining two-dimensional graphene sheets (G), one-dimensional Si nanowires (SiNW), and carbon nanotubes (CNT) through the cyclization process of polyacrylonitrile (PAN). The integrated electrode features a G/SiNW framework enveloped by a conformal coating consisting of cyclized PAN (cPAN) and CNT. This configuration establishes interconnected electron and lithium-ion transport channels, coupled with a rigid-flexible encapsulated coating, ensuring both high conductivity and resistance against the substantial volume changes in the electrode. The unique multidimensional structural design enhances the rate performance, cyclability, and structural stability of the integrated electrode, yielding a gravimetric capacity (based on the total mass of the electrode) of 650 mAh g-1 after 1000 cycles at 3.0 A g-1. When paired with a commercial LiNi0.5Co0.2Mn0.3O2 cathode, the resulting full cell retains 84.8% of its capacity after 160 cycles at 2.0 C and achieves an impressive energy density of 435 Wh kg-1 at 0.5 C, indicating significant potential for practical applications. This study offers valuable insights into comprehensive electrode structure design at the electrode level for Si-based materials.

High fractal-dimensional carbon conductive agent for improving the Li storage performance of Si-based electrode

Constructing stable Si electrodes with high areal capacity is crucial for improving the total energy density of lithium ion batteries (LIBs). However, it remains challenging because the poor intrinsic conductivity and serious pulverization of Si usually lead to the active material falling-off from the conductive network. Herein, we demonstrate novel spatially extended graphene ribbons with a high fractal-dimension structure (HFGR-400), which can construct highly conductive and mechanically reinforced networks when used as the conductive agent for Si electrodes. The HFGR-400 added electrode shows 1.5–3.2 times higher conductivity and 1.4–2.3 times larger peeling strength than those of the commonly used carbon conductive agent added electrodes. Moreover, the flexible HFGR-400 ribbons with appropriate amount of functional groups ensure large contact area and strong interfacial interaction with Si particles, but without blocking the ion transport channels. Therefore, the HFGR-400 added Si electrode exhibits good cycle stability (2051.8 mAh/g after 200 cycles) and high rate performance. Moreover, the high Si mass loading HFGR-400 electrode shows a competitive areal capacity of 3.5 mAh cm−2 after 200 cycles, superior to most of the reported Si-based electrodes. Our work highlights the importance of conductive agents with high fractal-dimension structure for practical Si-based electrodes.

A stable and true-blue emissive hexacoordinate Si(IV) N-heterocyclic carbene complex and its use in organic light-emitting diodes.

A neutral hexacoordinate Si(IV) complex containing two tridentate N-heterocyclic carbene ligands is synthesised and characterized by X-ray crystallography, optical spectroscopy, electrochemistry and computational methods. The stable compound exhibits remarkable deep-blue photoluminescence particularly in the solid state, which enables its use as an electroluminescent material in organic light-emitting diodes.

(Digital Presentation) Unraveling of the Morphology and Chemistry Dynamics in the FEC-Generated Silicon Anode SEI across Delithiated and Lithiated States

The silicon solid electrolyte interphase (SEI) faces cyclical cracking and reconstruction due to the ~350% volume expansion of Si which leads to shortened cell life during electrochemical cycling. Understanding the SEI morphology/chemistry and more importantly its dynamic evolution from delithiated and lithiated states is paramount to engineering a stable Si anode. Fluoroethylene carbonate (FEC) is a preferred additive with widely demonstrated enhancement of the Si cycling. Thus, insights into the effects of FEC on the dynamics of the resulting SEI may provide hints toward engineering the Si interface. Herein, ATR-FTIR, AFM, tip IR, and XPS probing all show pronounced relative invariance of the FEC-generated SEI compared to the FEC-free SEI between adjacent lithiated and delithiated states beyond the formation cycles. The SEI of Si thin film model surfaces in the baseline 1 M LiPF6 in EC:EMC (1:1) undergoes major morphological and chemical speciation swings between half-cycles while comparatively the SEI upon addition of FEC displays far less dynamic evolution. This morphology and chemistry stability of the FEC-SEI supports the enhanced cycling stability of silicon anodes in FEC-containing electrolytes. The experimental evidence gathered suggests that the FEC-SEI invariance is enabled by an elastomeric polycarbonate matrix that preserves the SEI integrity against the expansion of silicon upon lithiation. In turn, less electrolyte-consuming reconstruction occurs which manifests as and high LiF content from one half-cycle to the next. This work provides critical insights to enhance the silicon anode stability via targeted SEI engineering, namely that LiF protected by an elastomeric protective matrix may be key to buffering the unavoidable mechanical disruption. Figure 1

Probing surface Earth reactive silica cycling using stable Si isotopes: Mass balance, fluxes, and deep time implications.

Geological reservoir δ30Si values have increasingly been applied as paleoclimate and paleoproductivity proxies. Many of these applications rely on the assumption that the surface Earth Si isotope budget is in mass balance with bulk silicate Earth, such that trends in δ30Si over time can be attributed to changes in flux to or from key silica reservoirs. We compiled δ30Si data from modern reservoirs representing the major sources and sinks of surface Earth reactive silica, to which we applied an inverse model to test assumptions about mass balance. We found that δ30Si values of reverse weathering products must closely match those of diatoms, conflicting with previous assumptions. Model results also revealed that of the 19 to 21 teramoles per year Si released during silicate mineral weathering, ~10 to 18 teramoles per year is stored in terrestrial silica sinks, consistent with assumptions of incongruent weathering reactions. Our results demonstrated that the modern silica cycle summary is in isotopic mass balance.

Surface regulation of Si composite anode via synergistic coupling and Ti[sbnd]C bond for stable cycling lithium-ion battery

Silicon holds bright promise as the anode material for next-generation lithium-ion batteries (LIBs). Unfortunately, it is limited by enormous volume expansion and fast capacity fading in long-cycling or large current density. Here, we propose an in-situ assembling path to form a stable Si nanocomposite by introducing bicontinuous TiO2-C layer and graphene nano-sheets, and further enhance the stability for long-term LIBs. The enhanced synergistic coupling of graphene and bicontinuous TiO2-C layer and introduced TiC bond effectively improve long-cycling structural stability of Si nanocomposite for promising LIBs anode material. This anode material exhibits high capacity, long-term cycling and high-rate performance. Especially, it showed the high reversible capacities of 2147.6 mA h g−1 at 0.5 A g−1 after 800 cycles and 1328.2 mA h g−1 at 2 A g−1 after 500 cycles, which is much better than that of TiO2-C@Si and nano Si anodes. Moreover, the full cell including this composite anode and commercial LiFePO4 cathode exhibits a high capacity retention after 100 cycles. Our work demonstrates that this surface functionalization strategy can enhance synergistic coupling and introduce TiC bond to regulate the stability of Si nanocomposite as long-cycling LIBs anode.

Annealing behavior of AlSi10Mg alloy fabricated by laser powder bed fusion

The AlSi10Mg alloy fabricated by laser powder bed fusion was subjected to isochronal annealing for 2h at temperatures in the range of 100–520 °C. Recovery and grain growth of the annealed samples were investigated by combining EBSD and in situ TEM techniques. A bimodal grain size distribution with grain sizes of 0.9 μm and 2.3 μm was developed in the initial sample, where large grains were found in the interiors of melt pools and most of small grains were distributed along melt pool boundaries. In-situ TEM investigations revealed that nucleation that occurs at the melt pool boundaries is as a consequence of migration of high angle boundaries during annealing. A slight increase in grain sizes was discovered during high-temperature heat treatment, indicating the remarkable thermal stability of the alloy compared to conventional cast Al-Si alloys. This is explained by the fact that the stable eutectic Si structure, which was originally formed during rapid solidification, can effectively retard grain boundary migration during recrystallization.

Solids containing Si-O-P bonds: is the hydrolytic sol-gel route a suitable synthesis strategy?

AbstractMaterials based on silicon-phosphorus mixed oxides have traditionally attracted interest in electronics, optics, catalysis, and related fields. The preparation of a solid containing stable Si–O–P linkages is a huge challenge due to their intrinsic instability to hydrolysis in a wet atmosphere. On the other hand, most technological applications of these materials, such as protonic conductive membranes in fuel cells and water-tolerant solid acid catalysts, are related to their interaction with water; consequently, suitable synthesis procedures that positively face this tradeoff are mandatory. Besides the traditional high-temperature techniques, sol-gel synthetic methods represent a viable, low-cost alternative, allowing for the preparation of high-purity materials with a homogeneous distribution of the components at the atomic scale. Si–O–P linkages are easily obtained by nonhydrolytic sol-gel routes, but only in inert and dry atmosphere. Conversely, hydrolytic routes offer opportunities to control the structure of the products in a wide range of processing conditions. The present review aims at providing an overall picture of the research on the sol-gel synthesis of phosphosilicate and related materials and theisr different applications, emphasizing how the interest in these systems is still lively, considering both conventional and emerging applications, such as flame retardance. The incorporation of Si–O–P nanostructures in polymer composites, coatings, and textiles is indeed a promising strategy to improve properties like thermal stability and fire resistance; however, their in-situ synthesis brings about additional difficulties related to the reactivity of the precursors. The perspectives linked with the development of Si–P-based materials are finally outlined. Graphical Abstract

Energetics of silicon in the bulk and near surfaces of tungsten: a first-principles study

Siliconization of the tokamak walls is a candidate method to improve plasma confinement in fusion tokamaks containing tungsten plasma facing components (W PFCs). To understand the interactions of silicon (Si) with W, the Si behavior in bulk W, and near three low-index W surfaces ((100), (110) and (111)) has been investigated using first-principles density functional theory. In bulk W, Si interstitial atoms have a low solution ability and high mobility, and Si atoms can be strongly trapped by W vacancies. The interaction between two Si adatoms is responsible for the stability of adatom superstructures on W surfaces, consistent with previous experimental observation (Tsong and Casanova 1981 Phys. Rev. Lett. 47 113). Although the coverage dependence of Si adsorption and diffusion energetics on surfaces is related to surface orientation, the W(110) surface has lower Si adsorption affinity and higher Si diffusivity than either the W(111) or W(100) surfaces. The most stable Si adatom superstructure on W surfaces is: square c(2 × 2) pattern on W(100) covered with 0.5 ML Si; rectangular c(4 × 2) pattern on W(110) with 0.25 ML Si; and rhombus p(1 × 1) pattern on W(111) with 1 ML Si. The coverage dependence of Si mobility on/toward W surfaces is generally related to the stability of the Si superstructures as a function of coverage on each surface. Interestingly, Si adatoms prefer to transport below the surface and into W subsurface by an exchange mechanism with W atoms, indicating the likelihood of epitaxial growth of W silicide layers on W surfaces during the operation of W PFCs.

Separating Si phases from diagenetically-modified sediments through sequential leaching

Silicon (Si) phases such as biogenic silica, lithogenic silicate and authigenic silica/silicate in marine sediments provide valuable information about past Si cycling. Wet-chemical sequential leaching methods are often applied to extract different Si phases from marine sediments to study Si diagenetic processes in shallow subsurface. The potential of this method to separate Si phases from deeply-buried and diagenetically-modified sediments has not been systematically examined. We applied a sequential leaching protocol to drill core sediments retrieved from the Ulleung Basin, East/Japan Sea. We performed geochemical (elemental abundance and stable Si isotopes, δ30Si) and microscopic (X-ray diffraction and scanning electron microscope) analyses to monitor leaching efficiency in separating different Si phases. We show that, prior to alkaline leaching, applying weak acid is able to remove metal oxide and/or clay-like phases. The following Na2CO3 leaching, based on a commonly-adopted protocol, is able to dissolve some but not all diatoms. The results of elemental contents and δ30Si values of leachates suggest that, in diagenetically-modified sediments, either a longer digesting time or a harsher alkaline leaching is needed to dissolve all diatoms. This is attributed to increased resistance of diatoms to Na2CO3 leaching as a result of reduced surface area and/or improved SiO2 tetrahedron ordering during diagenetic processes over time and burial depths. Lithogenic silicate minerals can be dissolved by NaOH and potentially separated from diatoms if the latter is completely removed in the preceding leaching steps. Even if a trace amount of diatom is left undissolved in the NaOH leaching, it is still possible to separate the two through a mass balance calculation given the knowledge of composition for the two end-members. We conclude that a successful separation of Si phases in diagenetically modified sediments relies on the knowledge of elemental abundance and even δ30Si values of the leachates, as well as information such as species of Si-skeleton organisms, contents and maturation degree of biogenic silica.

Silicon oxynitride thin films by plasma-enhanced atomic layer deposition using a hydrogen-free metal-organic silicon precursor and N2 plasma

We investigated the growth mechanism of SiOxNy films deposited via plasma-enhanced atomic layer deposition at low temperatures (100–300 °C) using a tetraisocyanate silane (Si(NCO)4) precursor and N2 plasma. By using tetraisocyanate silane, which does not contain hydrogen, we were able to deposit SiOxNy with notably less hydrogen, around 3–5%, compared to using silicon precursors that contain hydrogen. Additionally, the precursor ligands, including oxygen, react with surface amine groups (-NH2) to form Si–N–O bonds. Therefore, by understanding the adsorption mechanism of the precursor and controlling the temperature that can affect the bond formation, we can successfully produce SiOxNy films without any oxidizing source. We utilized density functional theory to explore the adsorption mechanism during the deposition of SiOxNy films and proposed a possible adsorption pathway of the precursors and by-products on the surface. We also employed various characterization techniques, such as spectroscopic ellipsometry, X-ray photoelectron spectroscopy, X-ray reflectometry, secondary ion mass spectroscopy, and current-electric field and capacitance-voltage analyses to establish correlations between the composition and dielectric properties of the thin films. Increasing the deposition temperature results in an increased presence of stronger and more stable Si–N bonds compared to Si–O and O–N bonds. As a result, the dielectric constant of the SiOxNy film increased from 5.8 to 7.4, while the leakage current density decreased from 1.52 × 10−8 A/cm2 to 8.56 × 10−10 A/cm2. Additionally, the counterclockwise hysteresis decreased from 0.16 V to 0.07 V as the amount of hydrogen in the SiOxNy film decreased. This can be interpreted as a reduction in hydrogen impurities, which act as charge trapping sites within the film, leading to a decrease in hysteresis with increasing temperature.