In this paper the authors describe a theoretical simple statistical modelling of relaxation process in metal-oxide semiconductor devices that governs its degradation. Basically, starting from an initial state where a given number of traps are occupied, the dynamics of the relaxation process is measured calculating the density of occupied traps and its fluctuations (second moment) as function of time. Our theoretical results show a universal logarithmic law for the density of occupied traps $\bar{<n(t)>} \sim ϕ(T,E_{F}) (A+B \ln t)$, i.e., the degradation is logarithmic and its amplitude depends on the temperature and Fermi Level of device. Our approach reduces the work to the averages determined by simple binomial sums that are corroborated by our Monte Carlo simulations and by experimental results from literature, which bear in mind enlightening elucidations about the physics of degradation of semiconductor devices of our modern life.
Environmental contamination and human exposure to dyes have dramatically increased over the past decades because of their increasing use in such industries as textiles, paper, plastics, tannery and paints. These dyes can cause deterioration in water quality by imparting color to the water and inducing the photosynthetic activity of aquatic organisms by hindering light penetration. Moreover, some of the dyes are considered carcinogenic and mutagenic for human health. Therefore, efficient treatment and removal of dyes from wastewater have attracted considerable attention in recent years. Photoca…
We report on the dielectric degradation of Rare-Earth Oxides (REOs), when used as interfacial buffer layers together with HfO2 high-k films (REOs/HfO2) on high mobility Ge substrates. Metal-Oxide-Semiconductor (MOS) devices with these stacks,show dissimilar charge trapping phenomena under varying levels of Constant- Voltage-Stress (CVS) conditions, which also influences the measured densities of the interface (Nit) and border (NBT) traps. In the present study we also report on C-Vg hysteresis curves related to Nit and NBT. We also propose a new model based on Maxwell-Wagner instabilities mecha…
A number of degradation mechanisms have been observed during the long-term operation of solid oxide electrolysis cells (SOEC). Using an electrolyte charge carrier transport model, we quantify the oxygen potentials across the electrolyte and thereby provide insights into these degradation mechanisms. Our model describes the transport of charge carriers in the electrolyte when the oxygen partial pressure is extremely low by accounting for the spatial variation of the concentration of oxygen vacancies in the electrolyte. Moreover, we identify four quantities that characterize the distribution of …
Interdiffusion between the yttria stabilized zirconia (YSZ) electrolyte and the gadolinia doped ceria (CGO) barrier layer is one of the major causes to the degradation of solid oxide fuel cells (SOFCs). We present in this work experimental investigations on CGO-YSZ bi-layer electrolyte sintered at 1250 C or 1315 C and element transport as a function of sintering temperature and dwelling time. In order to quantitatively simulate the experimental observations, the CALPHAD-type thermodynamic assessment of the CGO-YSZ system is performed by simplifying the system to a CeO2-ZrO2 quasi-binary system…
In this paper, we report the synthesis of reduced Graphene Oxide-Tin Oxide nanocomposite and the effectiveness of this composite in decolorizing and degrading Methylene Blue (MB). Tin Oxide was prepared by liquid phase co-precipitation method and reduced Graphene Oxide-Tin Oxide (rGO-SnO2) nanocomposite was prepared by solution mixing method. Tin Oxide nanoparticles (NPs) have been ardently investigated as photocatalyst for water purification and environment decontamination but the photon generated electron and hole pair (EHP) recombination is one of the limiting factors. Reduced Graphene Oxid…
The oxygen vacancy is a crucial intrinsic defect in metal-ultrathin oxide semiconductor heterostructures, and its formation at an interface is of great importance in determining the device performance and degradation. This paper presents an ab initio thermodynamic study of oxygen vacancies at metal/oxide interfaces. Electronic energies and entropies are calculated for defective interface systems, as a function of interface-vacancy distance. The study indicates that oxygen vacancies near the interface modify its bonding structure, and significantly change the thermodynamic properties of the sys…
The development of novel functional materials in experimental labs combined with computer-based compound simulation brings the vision of materials design on a microscopic scale continuously closer to reality. For many applications interface and surface phenomena rather than bulk properties are key. One of the most fundamental qualities of a material-vacuum interface is the energy required to transfer an electron across this boundary, i.e. the work function. It is a crucial parameter for numerous applications, including organic electronics, field electron emitters, and thermionic energy convert…
Renewable energy conversion and storage, and greenhouse gas emission-free technologies are within the primary tasks and challenges for the society. Hydrogen fuel, produced by alkaline water electrolysis is fulfilling all these demands, however the technology is economically feeble, limited by the slow rate of oxygen evolution reaction. Complex metal oxides were suggested to overcome this problem being low-cost efficient catalysts. However, the insufficient long-term stability, degradation of structure and electrocatalytic activity are restricting their utilization. Here we report on a new pero…
Decoding Oxygen K-edge Fingerprints of NCM-811 Degradation via Ab Initio Many-Body Theory and High-Throughput Screening of Crystal Proxies
Carl von Ossietzky Universit\"at Oldenburg, Institute of Physics, 26129 Oldenburg, Germany；Department Interface Design, Helmholtz-Zentrum Berlin f\"ur Materialien und Energie GmbH, Berlin, Germany；Friedrich-Schiller-Universit\"at Jena, Institute of Condensed Matter Theory
High-Temperature Hydrogen Sensors Based on Gallium Oxide Heterojunction Diodes
Materials Science Center, National Laboratory of the Rockies（国家落基山实验室材料科学中心）；Department of Metallurgical and Materials Engineering, Colorado School of Mines（科罗拉多矿业学院冶金与材料工程系）
Characterizing electrochemical energy conversion devices during operation is an important strategy for correlating device performance with the properties of cell materials under real operating conditions. While operando characterization has been used extensively for low temperature electrochemical cells, these techniques remain challenging for solid oxide electrochemical cells due to the high temperatures and reactive gas atmospheres these cells require. Operando X-ray diffraction measurements of solid oxide electrochemical cells could detect changes in the crystal structure of the cell materi…
Thin layers of black phosphorus present an ideal combination of a 2D material with a tunable direct bandgap and high carrier mobility. However the material suffers from degradation in ambient conditions due to an oxidation reaction which involves water, oxygen and light. We have measured the spatial profile of the conductivity on flakes of black phosphorus as a function of time using scanning microwave impedance microscopy. A microwave excitation (3 GHz) allows to image a conducting sample even when covered with a dielectric layer. We observe that on bare black phosphorus, the conductivity cha…
A novel design has been proposed for a facile and rapid build-up of highly tailorable nanostructured multishells on metal oxide particles (graphene/TiOx@TiO2) under a dry inert atmosphere to maximize the visible-light photocatalytic performance. We also thoroughly and systematically investigated the as-prepared nanostructured particle surface and the mechanisms of the extraordinary in-situ graphene growth on the TiOx@TiO2 nanoparticles achieved by a rapid-concomitant reaction in the metal oxide (TiO2)/polymer (polymethyl methacrylate) interface under microwave irradiation. The as-prepared comp…
Metal oxides have been extensively investigated and applied in environmental remediation and protection, energy conversion and storage. Most of these diverse applications are results of a large diversity of the electronic states of metal oxides. Noticeably, however, numerous metal oxides have obstacles for applications in catalysis because of low density of active sites in these materials. Size reduction of oxide catalyst is a strategy to improve the active site density. Here, we demonstrate the fabrication of single atomic metal oxide in which the oxide size reaches its minimum. However, the …
The investigation of the defect chemistry of solid oxides is of central importance for the understanding of redox processes. This can be performed by measuring conductivity as a function of the oxygen partial pressure, which is conventionally established by using buffer gas mixtures or oxygen pumps based on zirconia. However, this approach has some limitations, such as difficulty regulating oxygen partial pressure in some intermediate-pressure regions or the possibility of influencing the redox process by gases that can also be incorporated into the oxide or react with the surface via heteroge…
Visible-light photocatalyst titanium dioxide (TiO2) was successfully prepared via a novel and facile single-mode microwave assisted synthesis process. In this one-step synthesis, Ti as target material selectively oxides in magnetic field throughout rapid heating, whose process requires less energy consumption and short time. In obtained TiO2, self-doping of Ti3+ was confirmed, which makes TiO2 performed sufficient light absorption in visible region with wavelength above 400 nm. Such Ti3+ self-doped TiO2 exhibits much narrower optical bandgap (2.14 eV) to compare with stoichiometric TiO2 (3.0-3…
This article identifies the process of crystallization of thin high-$κ$ dielectric films and an optimal range of annealing temperature in the field of high-$κ$ dielectric-based metal-oxide-semiconductor (MOS) technology for its improved electrical performances. Differential Scanning Calorimetry (DSC) technique is employed to understand the thermal behaviour of thin high-$κ$ dielectric films of HfO$_2$, deposited by rf sputtering, on Si. The exothermic trends of the DSC signal and Grazing Incidence X-ray diffraction (GIXRD) data indicate an amorphous to crystalline transition in the high-$κ$ fi…
Certain two-dimensional (2D) materials exhibit intriguing properties such as valley polarization, ferroelectricity, superconductivity and charge-density waves. Many of these materials can be manually assembled into atomic-scale multilayer devices under ambient conditions, owing to their exceptional chemical stability. Efforts have been made to add a magnetic degree of freedom to these 2D materials via defects, but only local magnetism has been achieved. Only with the recent discoveries of 2D materials supporting intrinsic ferromagnetism have stacked spintronic devices become realistic. Assembl…
Graphene's linear bandstructure and two-dimensional density of states provide an implicit advantage for sensing charge. Here, these advantages are leveraged in a deeply depleted graphene-oxide-semiconductor (D2GOS) junction detector architecture to sense carriers created by ionizing radiation. Specifically, the room temperature response of the silicon-based D2GOS junction is analyzed during irradiation with 20 MeV Si4+ ions. Detection was demonstrated for doses ranging from 12-1200 ions with device functionality maintained with no substantive degradation. To understand the device response, D2G…
Automating the analysis of micron-scale synchrotron diffraction data on inhomogeneous polycrystalline samples: a solid oxide electrolysis cell case study
Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory（斯坦福同步辐射光源，SLAC国家加速器实验室）；Materials, Chemical, and Computational Sciences Directorate, National Laboratory of the Rockies（落基山国家实验室材料、化学与计算科学部）；Department of Materials Science and Engineering & Department of Chemistry, University of Pennsylvania（宾夕法尼亚大学材料科学与工程系与化学系）
Transition metal oxides (TMOs) like MoOx are increasingly explored as hole transport layers for perovskite-based solar cells. Due to their large work function, the hole collection mechanism of such solar cells are fundamentally different from other materials like PEDOT: PSS, and the associated device optimizations are not well elucidated. In addition, the prospects of such architectures against the challenges posed by ion migration are yet to be explored - which we critically examine in this contribution through detailed numerical simulations. Curiously, we find that, for similar ion densities…
High-quality Nano-patterning of Oxide Interfaces Using Transferred Gold Mask
University of Science and Technology of China（中国科学技术大学）；Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China（中国科学技术大学微尺度物质科学国家研究中心）；Hefei National Laboratory, University of Science and Technology of China（中国科学技术大学合肥国家实验室）
High-Mobility Indium Native Oxide Transistors via Liquid-Metal Printing in Air
The Australian National University（澳大利亚国立大学）；University of New South Wales (UNSW Sydney)（新南威尔士大学）；Australian National Fabrication Facility, Research School of Physics, The Australian National University（澳大利亚国立大学物理研究学院澳大利亚国家制造设施）
Degradation Dynamics of Perovskite Solar Cells Under Fixed Reverse Current Injection
University of Washington（华盛顿大学）；University of Colorado Boulder（科罗拉多大学博尔德分校）；Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder（科罗拉多大学博尔德分校可再生能源与可持续能源研究所）；University of Arizona（亚利桑那大学）
Sarin is a very lethal synthetic organophosphorated compound that inhibits the nervous system muscle control. Although not used as a chemical weapon anymore, it still worries the authorities regarding possible use by terrorists. Most of the studies about sarin are theoretical/computational due to its high lethality and are concentrated in its detection and degradation. Few studies are about air filtration from sarin gas. Here, the potential of graphene oxide-based membranes to filter air from sarin/air mixtures is investigated by classical molecular dynamics simulations. Membranes formed by on…
Decoupling Trap States in Amorphous Oxide Semiconductor Transistor Using a Conductive-Semiconducting-Conductive MOS Structure
College of Integrated Circuits, Zhejiang University（浙江大学集成电路学院）；Department of ECE, National University of Singapore（新加坡国立大学电子与计算机工程系）；Zhejiang ICsprout Semiconductor Co., Ltd（浙江ICsprout半导体有限公司）
Access Rate-Dependent Endurance Behavior of Ferroelectric Hafnium Zirconium Oxide Capacitors
NaMLab gGmbH（NaMLab有限公司）；Queen’s University Belfast（贝尔法斯特女王大学）；Technical University Dresden（德累斯顿工业大学）；Intel Foundry（英特尔代工）；University Applied Sciences, Department of Applied Sciences and Mechatronics（应用科学大学应用科学与机电工程系）
A high reversible capacity is a key feature for any rechargeable battery. In the lithium-ion battery technology, tin-oxide anodes do fulfill this requirement, but a fast loss of capacity hinders a full commercialization. Using first-principles calculations, we propose a microscopic model that sheds light on the reversible lithiation/delithiation of SnO and reveals that a sintering of Sn causes a strong degradation of SnO-based anodes. When the initial irreversible transformation ends, active anode grains consist of Li-oxide layers separated by Sn bilayers. During the following reversible lithi…
The enhanced degradation of organophosphorous-based chemical warfare agents (CWAs) on metal-oxide surfaces holds immense promise for neutralization efforts; however, the underlying mechanisms in this process remain poorly understood. We utilize large-scale quantum calculations for the first time to probe the high-temperature degradation of diisopropyl methylphosphonate (DIMP), a nerve agent simulant. Our Born-Oppenheimer molecular dynamics (BOMD) calculations show that the $γ$-Al$_2$O$_3$ surface shows immense promise for quickly adsorbing and destroying CWAs. We find that the alumina surface …
The magnetic tunnel junction is a cornerstone of spintronic devices and circuits, providing the main way to convert between magnetic and electrical information. In state-of-the-art magnetic tunnel junctions, magnesium oxide is used as the tunnel barrier between magnetic electrodes, providing a uniquely large tunnel magnetoresistance at room temperature. However, the wide bandgap and band alignment of magnesium oxide-iron systems increases the resistance-area product and causes challenges of device-to-device variability and tunnel barrier degradation under high current. Here, we study using fir…
In situ Al$_2$O$_3$ passivation of epitaxial tantalum and aluminum films enables long-term stability in superconducting microwave resonators
Grad. Institute of Applied Physics and Dept. of Physics, National Taiwan University（国立台湾大学应用物理研究所及物理系）；Department of Physics, National Tsing Hua University（国立清华大学物理系）；National Synchrotron Radiation Research Center（国家同步辐射研究中心）；Taiwan Semiconductor Research Institute（台湾半导体研究院）
We have studied high temperature thermal behavior of 1H, 1H, 2H, 2H-Perfluorooctyl-trichlorosilane (FOTS) and Octyltrichlorosilane (OTS) molecules self assembled on titanium dioxide (TiO2) nanoparticles using advanced microscopy and spectroscopy technique such as Scanning Electron Microscope (SEM), Dynamic Light Scattering (DLS), X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). FOTS SAM and OTS SAM coated TiO2 nanoparticles were heated to different temperature range from room temperature (RT) to 550oC. We characterized nano-microstructure and size distribution of FOT…
Materials with good carrier mobilities are desired for device applications, but in real devices the mobilities are usually limited by the presence of interfaces and contacts. Mobility degradation at semiconductor-dielectric interfaces is generally attributed to defects at the interface or inside the dielectric, as is the case in Si/SiO2 structures, where processing does not introduce detrimental defects in the semiconductor. In the case of SiC/SiO2 structures, a decade of research focused on reducing or passivating interface and oxide defects, but the low mobilities have persisted. By invoking…
Halide perovskites excel in the pursuit of highly efficient thin film photovoltaics, with power conversion efficiencies reaching 25.5% in single junction and 29.5% in tandem halide perovskite/silicon solar cell configurations. Operational stability of perovskite solar cells remains a barrier to their commercialisation, yet a fundamental understanding of degradation processes, including the specific sites at which failure mechanisms occur, is lacking. Recently, we reported that performance-limiting deep sub-bandgap states appear in nanoscale clusters at particular grain boundaries in state-of-t…
CuAl2O4 is a normal spinel oxide having quantum spin, S=1/2 for Cu2+. It is a rather unique feature that the Cu2+ ions of CuAl2O4 sit at a tetrahedral position, not like the usual octahedral position for many oxides. At low temperatures, it exhibits all the thermodynamic evidence of a quantum spin glass. For example, the polycrystalline CuAl2O4 shows a cusp centered at ~2 K in the low-field dc magnetization data and a clear frequency dependence in the ac magnetic susceptibility while it displays logarithmic relaxation behavior in a time dependence of the magnetization. At the same time, there …
