Change In Interface States Research Articles

Failure Mechanism and Residual Stress Analysis of Crystal Materials for the Thermal Battery

This paper investigates the thermal battery as a research topic. We conducted an in-depth analysis of various thermal battery aspects, such as the cathode material CoS2 and electrolyte material morphology, crystal type, and interface state changes before and after service. The aim was to explore the core reaction and main failure mechanisms of the thermal battery. Prior to the reaction, the thermal battery cathode and electrolyte material consisted of pure-phase CoS2 and a composition of MgO-LiF/LiBr/LiCl. After service, the cathode and electrolyte of the single thermal battery exhibited significant morphological alterations caused by the presence of a molten state. The cathode transformed from CoS2 to Co3S4 and Co9S8 together with the presence of a marginal quantity of Co monomers visible throughout the discharge process, which was confirmed by means of XRD and XPS analyses. After the reaction, the electrolyte material was primarily made up of LiF, LiBr, and LiCl while the crystal components remained largely unaltered, albeit with apparent morphological variations. As was deduced from the thermodynamic analysis, the cathode material’s decomposition temperature stood at 655 °C, exceeding the working temperature of the thermal battery (500 °C) by a considerable margin, which is indicative of outstanding thermal durability within the thermal battery’s operational temperature range. Furthermore, the discharge reaction of the positive electrode was incomplete, resulting in reduced CoS2 residue in the thermal battery monomer after service. The reaction yielded a combination of Co3S4, Co9S8, and small amounts of Co monomers, indicating possible inconsistencies in the phase composition of the pole piece during the reaction process. In this study, we examine the distribution of residual stress in the thermal battery under various operating conditions. The simulation results indicate that exposure to a 70 °C environment for 2 h causes the maximum residual stress of the battery, which had an initial temperature of 25 °C, to reach 0.26 GPa. The thermal battery subjected to an initial temperature of 25 °C exhibited a maximum residual stress of 0.42 GPa subsequent to a 2-hour exposure to a temperature of −50 °C.

Investigation on γ radiation effects of N-channel VDMOSFETs irradiated without electric field stress

The ionizing radiation response of a kind of commercial n-channel VDMOSFETs irradiated without external electric field stress is investigated. The effects of total dose, dose rate and H2 ambient on the radiation response, and the post-irradiation annealing behaviors of the devices have been explored. The devices are degraded obviously after 1200 Gy (Si) γ radiation. No appreciable true dose rate effect (or Enhanced Low Dose Rate Sensitivity, ELDRS) has been observed in the tested devices. The small and irregular variations in performance degradation with dose rate are believed to come from the variability in the radiation response of the devices. In addition, the ambient of 100% H2 accelerates the total dose degradation of the devices. The γ radiation-induced performance degradation contains significantly negative shift of threshold voltage (Vth) and remarkable increase in off-state leakage current (Ileak), which are mainly caused by the increase in radiation-induced oxide-trapped charges. No obvious change in interface states is observed during the whole irradiation experiments and the annealing processes. The bias condition adopted in this work during irradiations is probably the reason for these unexpected phenomena. Furthermore, the annealing results indicate that the radiation-induced oxide-trapped charges seem to possess relatively stable properties, and could not be fully compensated or neutralized at room temperature (RT) or high temperatures, or under positive high electric field stress (PHEFS) of +70 V.

A New Methodology to Investigate the Effect of Stress and Bias on 2DEG and Drain Current of AlGaN/GaN Based Heterostructure

The effect of negative, neutral and positive stress by Si3N4 film on AlGaN layer of AlGaN/GaN based high electron mobility transistor (HEMT) heterostructure has been investigated by varying different stress values using Synopsys Sentaurus device simulation. This paper shows a relation between the stresses of passivation layer, two dimensional electron gas (2DEG) formed at the interface of AlGaN/GaN region and respective drain current. The increase in negative stress will result in the increase of 2DEG density, which will result in the increase of drain current. Additionally, the 2DEG density was found to be depended on the applied bias voltage, showing the higher drain sweep voltage will increase the 2DEG density. This study also provides the effect of stress on direct-current (DC) capacitance-voltage characteristics of device electrical performance. It suggests that the capacitance will be increased with the increasing positive stress, indicating the change in interface states due to stress effect.

Crawling Ajax-Based Web Applications through Dynamic Analysis of User Interface State Changes

Using JavaScript and dynamic DOM manipulation on the client side of Web applications is becoming a widespread approach for achieving rich interactivity and responsiveness in modern Web applications. At the same time, such techniques---collectively known as Ajax ---shatter the concept of webpages with unique URLs, on which traditional Web crawlers are based. This article describes a novel technique for crawling Ajax -based applications through automatic dynamic analysis of user-interface-state changes in Web browsers. Our algorithm scans the DOM tree, spots candidate elements that are capable of changing the state, fires events on those candidate elements, and incrementally infers a state machine that models the various navigational paths and states within an Ajax application. This inferred model can be used in program comprehension and in analysis and testing of dynamic Web states, for instance, or for generating a static version of the application. In this article, we discuss our sequential and concurrent Ajax crawling algorithms. We present our open source tool called Crawljax , which implements the concepts and algorithms discussed in this article. Additionally, we report a number of empirical studies in which we apply our approach to a number of open-source and industrial Web applications and elaborate on the obtained results.

Large Threshold Voltage Shifts of Nanostructured-Thin Film ZnS:Mn Electroluminescent Devices

We have studied electro-optical properties of nanostructured-thin film electroluminescent devices(NS-TFELD) with a nanosized-tantalum pentoxide(Ta2O5) insulator layer inserted into the ZnS:Mn phosphor layer. A large threshold voltage shift ΔVth has been observed in NS-TFELD. The change in the transferred charge △Q seems to relate to the large shifts of ΔVth, implying that the change in interface states due to the nanosized oxide layer will be responsible for the shifts of Vth.

Characterization of interface states in (Sr, Ca)TiO3−x based ceramics by ICTS analysis

Isothermal capacitance transient spectroscopy measurements were performed to study the reoxidizing induced change in interface states in (Sr, Ca)TiO3−x based ceramics. A discrete acceptor type trap level was detected with reoxidation below the oxidation temperature of grain surfaces, but two deep levels were detected with reoxidation above this temperature. These ICTS results are in good agreement with the previous report with the DLTS measurements. These interface states are considered to originate from chemisorbed oxygen (O2−, O−) on grain surfaces. The O− and O2− chemisorption levels contribute to the non-ohmic conduction with reoxidizing anneals below and above the oxidation temperature, respectively.