Degradation mechanism of oxide film on SIMP steel in LBE at temperatures above 550 °C

On oxidation film structure of SIMP steel exposed in stagnant oxygen-saturated LBE at 600 °C

Accelerated steam corrosion behavior of Fe-ion irradiated RAFM steel: The role of displacement damage

Gallium-doped zinc oxide (GZO) films were deposited at RT by dc planar magnetron sputtering under various total gas pressures (Ptot) ranging from 0.25 Pa to 2.5 Pa using Ar as the sputtering gas and a GZO ceramic oxide target. The GZO films showed highest crystallinity at Ptot = 2.0 Pa and showed clear degradation at a lower or higher Ptot. For a comparative study, Ne or Kr was also used as a sputtering gas. The mechanisms of degradation were investigated, considering the effects of bombardment of high-energy particles on the growing film surface and the energy of sputtered particles, where kinetic energies of these particles were estimated by Monte Carlo simulation. It was shown that sputtered particles lost sufficient energy for surface migration to form a crystalline structure at a higher Ptot. The high-energy neutrals of the sputtering gas (Ar0, Ne0, and Kr0) which recoiled from the target surface should be primarily responsible for the structural damage in the film at a lower pressure.

The microstructure, crystal structure, and morphology of oxide films growing on zirconium alloys have been studied to better understand the effect of tin on the corrosion of Zircaloy. Zr-Sn-Fe-Cr sheets whose tin content varied from 0.09 to 1.41% were prepared and corroded in 400°C static steam for 300 days. The weight gain increased consistently with tin content. When the oxide film thickness was the same among all specimens, glancing angle XRD and TEM examination indicated a thick tetragonal ZrO2 inner layer only on the low-tin content alloy. The distribution of tin in the oxide films was analyzed using high-resolution EDX. Tin was enriched at the boundaries of the oxide crystallites. Tin concentration at the crystallite boundaries increased with the tin content of the alloy. Tin oxide was observed at the crystallite boundaries of the monoclinic ZrO2 layer by a high-resolution TEM image. When the condensed tin is oxidized, it expands, transforming the oxide from tetragonal to monoclinic, which in turn leads to the loss of a dense oxide layer. The low-tin content alloy consequently shows high-corrosion resistance owing to the smaller amount of tin condensing at the oxide grain boundaries.

We evaluated the fill factor (FF) degradation mechanism in silicon heterojunction (SHJ) solar cells with high mobility In2O3 film as a high carrier mobility transparent conductive oxide (TCO) film. In particular, we focused on the electrode formation using a high productive screen-printing technique. We found the In2O3 film is easier to be reduced than the traditional TCO such as tin-doped indium oxide (ITO). Thus, the Ag atom inside the electrode is easily oxidized during the cure annealing process and results in higher contact resistance at electrode/TCO interface and deteriorate FF characteristic. We introduced novel cation catalyst additive for paste polymerization which is less reactive with In2O3 and improve the contact resistance by suppressing the silver oxidation. We also demonstrated SHJ cell fabrication and prove the effect of the developed silver paste.

Chapter 31 - Time-Dependent Device Performance: A Unified Treatment

Analysis of the oxidized surface of 90Nb-10Zr alloy after exposure to lithiated water with 0.01 M LiOH at 360 °C/18.6 MPa

Several pressurized water reactor nuclear plants around the world have experienced intergranular attack (IGA) on the secondary surface of the steam generator tubes in the hot leg crevices. The most common explanation for this type of tube defect is caustic attack. Boric acid is sometimes added to the secondary water as a counter measure for this problem. However, the exact cause of the IGA is not always positively identified and thus the boric acid additions may not ameliorate the problem. Therefore, an alternate approach to identify the causative agent is suggested. When a metal is put in a solution, an oxide film specific to the solution is formed. The formation and disruption of the oxide film on the metal surface has a close relationship with corrosion. The depth profile of thin films on Alloy 600, which were formed in various water chemistries, were investigated using Auger electron spectroscopy to obtain basic knowledge on the following: Effect of boric acid on thin film characteristics,Effect of possible causative materials of IGA such as Si, Pb, organics and Cu, other than caustic on thin film characteristics. As the results of this study, the following were determined: Boric acid can effectively aid in forming a protective film against caustic IGA when the boron concentration is at least 10,000 ppm.Contaminant solutions, including possible causative agents of IGA such as Si, Pb, organics and Cu, produce thin films specific to each solution. This information may be used as an indicator to determine what contaminant might be the possible causative agent of IGA when thin film analysis is performed on the defect area of pulled steam generator tubes.When the degradation mechanism is caustic IGA, soluble Cu may be detrimental since it selectively dissolves Fe and Ni resulting in a higher Cr content in the thin film.

12 - Hard Breakdown Characteristics in a 2.2-nm-thick SiO2 film

Ferritic Fe-based (FeCrX) alloys forming a protective chromium oxide film are used for providing electrical interconnection in high temperature Solid Oxide Fuel Cells (SOFC) are susceptible to degradation mechanisms in the presence of high temperatures (>600oC), and humid air. These translate by the increase in interconnect electrical contact resistance and the formation of volatile chromium species causing poisoning of the adjacent cathode. Modelling tools and techniques are increasingly becoming popular to gain better understanding of the degradation mechanisms that lead to the formation of volatile chromium species. This research work examines the oxidation behaviour of uncoated ferritic stainless steels system operated at temperature of 700oC in both wet (3% humidity) and dry conditions. A model is presented based on the physical processes involved. The model is able to predict the weight gain of the samples upon oxidation, the oxide film thickness, the volatilization of chromium and the useable lifetime of interconnects based on chromium depletion. Parameter determination from standard experiments is discussed along with the physical and design insights from the model. Perhaps most importantly the model provides recommendations regarding accelerated testing of FeCrX interconnects and control of the Chromia film thickness. Acknowledgements: This work was supported by the European FCH JU in project SCORED 2:0 under contract no. 325331 and the EPSRC.

The chemo-mechanical coupling effect has been widely investigated due to its important impact on many areas, such as Li-ion batteries, biomechanical engineering, hydrogen embrittlement, etc. Meanwhile, the chemo-mechanical coupling effect on the high temperature oxidation process is drawing increasing attention. During oxidation, stress can be induced in the oxide film and will in turn influence the diffusion process and oxidation kinetics. Understanding the coupling effect between stress and oxidation helps to illuminate the mechanism of material degradation and failure. In this work, a concise physical model is developed for oxidation kinetics at elevated temperatures considering the diffusion-stress coupling effect, where both the inward and outward diffusion are considered. The model prediction shows an excellent agreement with the experimental observation. Based on this physical model, we also proposed a parameter to characterize the effects of cation/anion diffusion as well as a phase diagram to describe the universal diffusion–oxidation growth process.

In this paper, the TCAD degradation model of IGZO using spatial distribution (X, Y) of physical parameters is proposed for the first time and is confirmed according to various channel length, active thickness, and bias stress conditions that agree with actual measurements. Oxygen vacancy in the presence of 2+ ionized states (VO 2+) in IGZO is stable. However, when band bending is severe, the electrons are captured, and the structural transition occurs as a neutral VO in the meta-stable state. This process is assumed to be a mechanism of IGZO degradation at high drain bias stress, and the electric field (>0.5M V/cm) and electron concentration (>1x1010 cm-3) in the channel are considered as the main factors of degradation and are modeled using the mapping function provided by Silvaco. Fig.1 show that the flow of development of degradataion model using TCAD. Based on the oxide degradation mechanism, the following mathematical model was proposed to determine the number of electrons captured by the electric field, Ɛ(X,Y) and the electron concentration n(X,Y) at each position in the oxide film according to equation 1. Here, ƐC and nc represent the critical electric field and electron concentration at which the deterioration starts, respectively, and 0.5 M V/cm and 1x1010 /cm3. ƐC represents the minimum energy required for metastable transition to the metastable state, and nc is a threshold value that rapidly increases the probability of occurrence of this event. These parameters can be very important physically, but they are now empirically derived from the measurement results. Figure 1

High-quality thin SiO/sub 2/ films are strongly needed for advanced integrated circuits such as CMOSFETs and EEPROMs. It is found that N/sub 2/O-nitrided SiO/sub 2/ film is more useful than NH/sub 3/-nitrided SiO/sub 2/ or pure SiO/sub 2/ film for obtaining high-performance CMOSFETs. However, the mechanism of hot-carrier degradation of CMOSFETs with these oxide films has not been discussed. A detailed study is reported on hot-carrier-induced degradation phenomena in nitrided SiO/sub 2/ gate CMOSFETs. It is confirmed that N atoms in gate oxide films prevent the generation of interface traps for NMOSFETs and H atoms accelerate electron trapping for PMOSFETs. Therefore, N/sub 2/O-nitrided gate oxide film free from H atoms is effective for obtaining high-performance CMOSFETs.

The reliability of flexible electronics depends on the mechanical integrity of functional materials under repeated deformation, yet research on their failure mechanisms across different configurations remains limited. This study investigates the mechanical failure and electrical degradation of conductive blanket films and island arrays on platinum (Pt)/polyethylene terephthalate (PET) flexible substrates subjected to up to 500 bending cycles. The goal is to assess whether converting brittle indium tin oxide (ITO) and ductile copper (Cu) blanket films into island configuration improves durability. Results show that the mechanical failure patterns and electrical stability of blanket films are highly material dependent. While the ductile Cu film cracked in the first bending cycle, it retained electrical stability up to 500 cycles. In contrast, the brittle ITO film exhibited immediate cracking and significant electrical degradation, with conductivity declining as cracks widened. These findings indicate that blanket films suit ductile materials but not for brittle ones. ITO and Cu islands remained crack-free after cyclic bending, preserving structural integrity. However, islands influenced stress distribution in the underlying Pt film, acting as stress raisers. Rigid ITO islands redistributed stress effectively, promoting an ordered crack pattern. Cracks initiated at vertical edges and propagated outward, leaving regions between islands crack-free. As cycles increased from 100 to 500, conductivity stabilized due to crack saturation and stress relief. In contrast, compliant Cu islands had little effect on stress distribution, leading to crack patterns similar to Pt/PET bilayers. Consequently, Cu island samples showed conductivity variations similar to Pt/PET bilayers, with resistance gradually increasing due to growing crack density.

Durability-enhanced monolithic inorganic electrochromic devices with tantalum-doped nickel oxide as a counter electrode