Generation Of Holes Research Articles

(Invited) Development of Nanoporous Structures and Oscillatory Behavior During Anodization of n-InP in Alkaline Electrolytes

Electrochemical etching of semiconductors under anodic conditions can lead to the growth of nanoporous structures. There has been extensive research in this area for silicon and III-V electrodes1-7. Porous structures are obtained3-7 when n-InP is anodized in aqueous KOH at concentrations of 2 mol dm-3 or greater; planar etching occurs below 1 mol dm-3. The observation of current oscillations during the anodization of semiconductors has been reported by several authors.8-11 Current oscillations on silicon in fluoride-containing electrolytes have been linked to the cyclic growth and dissolution of thin oxide layers. We have observed10,11 current oscillations on InP both in aqueous KOH and in aqueous (NH4)2S.A typical current-voltage curve of InP anodized in 5 mol dm-3 KOH is shown in Fig. 1. The anodic peak at 1.9 V (SCE) corresponds to the dissolution of InP leading to the formation of a porous InP layer that extends over 500 nm into the substrate. At higher potentials, sustained oscillations are observed.Porosity originates from pits in the surface creating domains of pores beneath a thin dense near-surface layer of ~40 nm.4 Each domain is connected to the surface via an individual channel, and eventually these domains merge to form a continuous porous layer. Pore propagation in InP in KOH is usually crystallographically oriented (CO), although it can be current-line-oriented (CLO) under certain conditions. We have proposed5 a three-step model of electrochemical nanopore formation that explains how crystallographically oriented etching can occur even though the rate-determining process (hole generation) occurs only at pore tips. The model shows that competition in kinetics between hole diffusion and electrochemical reaction determines the average diffusion distance of holes along the semiconductor surface and this, in turn, determines whether etching is crystallographic. If the kinetics of reaction is slow relative to diffusion, etching can occur at preferred crystallographic sites within a zone in the vicinity of the pore tip, leading to pore propagation in preferential directions. We believe that the model is generally applicable to electrochemical etching in III-V semiconductors.Current oscillations on n-InP in aqueous (NH4)2S occur above ~1.7 V(SCE). Similarly, in galvanostatic measurements oscillations in potential occur at higher current densities. A remarkable linear relationship is observed between the frequency of oscillation and the average current density. Thus, the oscillations exhibit a characteristic constant charge per cycle. Anodization of highly doped n-InP in aqueous KOH also shows current oscillations at higher potentials. In this case, however, the charge per cycle increases linearly with potential.The oscillatory current region in the InP/(NH4)2S system corresponds to growth of a thick porous In2S3 layer on the electrode. In contrast, the oscillatory region in the InP/KOH system corresponds to anodic dissolution of InP with the formation of a porous region near the surface. The characteristics of the InP/KOH system are very similar to reported behavior for silicon in HF, where porous silicon formation and anodic current oscillations are also observed.We will review our work on nanoporosity and oscillatory behavior in these systems and discuss the underlying mechanisms. References R.L. Smith and S.D. Collins, J. Appl. Phys 71, 8 (1992)H. Föll, J. Carstensen, S. Langa, M. Christophersen and I.M. Tiginyanu, phys. stat. sol. (a) 197, 61 (2003) N. Quill, D. N. Buckley, C. O’Dwyer and R. P. Lynch, J. Electrochem. Soc. 166, H3097 (2019)R. P. Lynch, C. O’Dwyer, N. Quill, S. Nakahara, S. B. Newcomb and D. Noel Buckley, J. Electrochem. Soc., 160, D260 (2013).R. P. Lynch, N. Quill, C. O'Dwyer, S. Nakahara and D. N. Buckley, Phys. Chem. Chem. Phys., 15, 15135 (2013).R. Lynch, C. O’Dwyer, D.N. Buckley, D. Sutton and S.B. Newcomb, ECS Trans 2, 131 (2006)C. O'Dwyer, D.N. Buckley, D. Sutton, and S.B. Newcomb, J. Electrochem. Soc. 153, G1039 (2006)S. Langa, J. Carstensen, I.M. Tiginyanu, M. Christophersen and H. Föll, Electrochem. Solid-State Lett., 4, G50 (2001)V. Parkhutik, Mater. Sci. Eng. B, 88, 269 (2002)E. Harvey, D. N. Buckley and S. N. G. Chu, Electrochem. Solid State Letters 5, G22 (2002)C. O’Dwyer, T. Melly, E. Harvey, D. N. Buckley, V. J. Cunnane, D. Sutton, and S. B. Newcomb in Proceedings of the 37th State-of-the-Art Program on Compound Semiconductors, PV 2002-14, pp. 275-285, (ISBN 1-56677-336-9, The Electrochemical Society, Pennington, NJ, 2002). Figure 1

(Invited) Development of Nanoporous Structures and Oscillatory Behavior During Anodization of n-InP in Alkaline Electrolytes

In the early stages of anodization of n-InP in KOH, isolated nanoporous domains form and eventually merge into a continuous layer. SEM and TEM cross-sections show clear evidence that these have the shape of truncated tetrahedrons and result from preferential pore progagation along the <111>A directions. We propose a three-step model of electrochemical nanopore formation that explains how crystallographically oriented etching can occur even though the rate-determining process occurs only at pore tips. The rate-determining Step 1 is the generation of holes at pore tips. If Step 2 (hole diffusion) is faster than Step 3 (electrochemical reaction) then etching can occur at preferred crystallographic sites, such as phosphorus dangling bonds, leading to pore propagation in preferential directions. Well-defined oscillations are observed under certain conditions when n-InP is anodized in either KOH or (NH4)2S. The oscillations in (NH4)2S, have a symmetric profile and the charge per cycle remains constant over a wide range of conditions: we propose a mechanism based on cyclical changes in the morphology of the InP surface beneath an In2S3 film. The exact mechanism of the oscillatory behavior in KOH is still unclear.

Black Hole Genealogy: Identifying Hierarchical Mergers with Gravitational Waves

Abstract In dense stellar environments, the merger products of binary black hole mergers may undergo additional mergers. These hierarchical mergers are naturally expected to have higher masses than the first generation of black holes made from stars. The components of hierarchical mergers are expected to have significant characteristic spins, imprinted by the orbital angular momentum of the previous mergers. However, since the population properties of first-generation black holes are uncertain, it is difficult to know if any given merger is first-generation or hierarchical. We use observations of gravitational waves to reconstruct the binary black hole mass and spin spectrum of a population including the possibility of hierarchical mergers. We employ a phenomenological model that captures the properties of merging binary black holes from simulations of globular clusters. Inspired by recent work on the formation of low-spin black holes, we include a zero-spin subpopulation. We analyze binary black holes from LIGO and Virgo’s first two observing runs, and find that this catalog is consistent with having no hierarchical mergers. We find that the most massive system in this catalog, GW170729, is mostly likely a first-generation merger, having a 4% probability of being a hierarchical merger assuming a 5 × 105 M ⊙ globular cluster mass. Using our model, we find that 99% of first-generation black holes in coalescing binaries have masses below M ⊙, and the fraction of binaries with near-zero component spins is less than (90% probability). Upcoming observations will determine if hierarchical mergers are a common source of gravitational waves.

Machining and Characterization of Double-Helical Grooves on Cylindrical Copper Parts by Wire Electric Discharge Turning

In the work, the design and development of a novel Wire-EDM setup with double-wire guide discs is presented. It facilitates sparks to be generated between the workpiece and wire at two locations separated by the helical pitch distance. This sparking causes two helical grooves to be generated simultaneously on the surface of the workpiece when it is given suitable rotational speed and table feed. In this work, machining is carried out on rods of 1.5 mm diameter. Helical groves with helix angles ranging from 35 to 500 were generated and characterized. This method of machining the double helical grooves with a single pass reduces the machining time and eliminates the complexities involved in machining one groove at a time. It was observed that the proposed method is suitable for machining double helical grooves with helix angles in the range of 40 - 50°. The parts produced by the mentioned method can be used as EDM tools for generation of high aspect ratio holes in turbine blades and injection nozzles.

Efficiency of Hot-Electron Generation in Plasmonic Nanocrystals with Complex Shapes: Surface-Induced Scattering, Hot Spots, and Interband Transitions

The generation of hot electrons is an intrinsic property of all plasmonic nanocrystals under illumination. However, the number of such excited electrons will strongly depend on the shape, material, and excitation wavelength. In this paper, we develop a practical self-consistent formalism to describe the generation of energetic electrons in a plasmonic nanocrystal with an arbitrary shape. We apply our formalism to gold nanospheres, nanorods, and nanostars. Among the investigated shapes, the nanostar geometry demonstrates the best performance, with an internal energy efficiency of ∼25%. This superior capability of hot-electron generation in the nanostars comes from the following factors: strong hot spots in the red spectral region, isotropic optical response, and the absence of interband transitions at the plasmonic resonance. Spherical gold nanocrystals show strong interband absorption at the plasmon resonance, and the related efficiency of the generation of hot holes in the d band can reach a level of 70%. By analyzing the energy performance of nanocrystals under CW illumination, we show that the most relevant parameter to consider is the rate of hot-electron generation, whereas the steady-state numbers of thermalized and nonthermalized electrons play secondary roles. The physical principles formulated in this study can be used to design a variety of plasmonic nanomaterials for applications in photocatalysis and photodetection.

Solution combusting synthesis of xFe-Bi2MoO6 nanoparticles with increased photocatalytic performance for organic pollutants degradation

The un-doping and Fe3+ doping hydrangea-like Bi2MoO6 nanoparticles (ie. BMO, 0.02%Fe-BMO, 0.05%Fe-BMO, 0.1%Fe-BMO, 0.15%Fe-BMO, 0.3%Fe-BMO, respectively) have been prepared through solution combusting synthesis. The serials samples were investigated by XRD, SEM, TEM, HRTEM, BET, XPS, UV–vis and PL means while the photocatalytic performance have been tested by the photo-degradation of RhB and TC. The results manifests that Fe3+ ions were doubtlessly doped into crystal texture of BMO and the photocatalytic performance of xFe-BMO photocatalyst was clearly influenced by the doping concentration of Fe3+ ions, due to the value of band gap was reduced as the doping concentration of Fe3+ ions increasing inch by inch. In addition, the Fe doped into BMO also can enhance the generation of photo-generated electrons and hole through the Fe3+/Fe2+ redox process, which contribute to the organic pollutants degradation. The results revealed that Fe doping dramatically improved the photocatalytic performance of pure BMO, and the 0.05Fe-BMO showed the optimum photocatalytic efficiency with the 93.9% and 88.7% photo-degradation rate for RhB and TC. Meanwhile, the better photocatalytic performance is because of the synergistic effect of Fe3+ ions and the multilayer wafer structure of BMO, which resulted in efficient surface reaction, narrower bandgap, rapid charge separation and improved light harvesting ability.

In Situ Visualization of Localized Surface Plasmon Resonance-Driven Hot Hole Flux.

Nonradiative surface plasmon decay produces highly energetic electron–hole pairs with desirable characteristics, but the measurement and harvesting of nonequilibrium hot holes remain challenging due to ultrashort lifetime and diffusion length. Here, the direct observation of LSPR‐driven hot holes created in a Au nanoprism/p‐GaN platform using photoconductive atomic force microscopy (pc‐AFM) is demonstrated. Significant enhancement of photocurrent in the plasmonic platforms under light irradiation is revealed, providing direct evidence of plasmonic hot hole generation. Experimental and numerical analysis verify that a confined |E|‐field surrounding a single Au nanoprism spurs resonant coupling between localized surface plasmon resonance (LSPR) and surface charges, thus boosting hot hole generation. Furthermore, geometrical and size dependence on the extraction of LSPR‐driven hot holes suggests an optimized pathway for their efficient utilization. The direct visualization of hot hole flow at the nanoscale provides significant opportunities for harnessing the underlying nature and potential of plasmonic hot holes.

Preparation and photocatalytic properties of hexagonal and orthogonal CuS micro-nanoparticles by an oil-water interface method

Hexagonal and orthogonal copper sulfide (CuS) micro-nanoparticles were prepared respectively at 120 °C and 180 °C for 5 h by an oil-water interface method. Through various characterizations, the results showed that spherical hexagonal and orthogonal CuS micro-nanoparticles were of rough surface and good crystallinity, respectively. Meanwhile, both the hexagonal and orthogonal CuS micro-nanoparticles exhibited effective degradation and recyclability to Rhodamine B (RhB) and Methylene blue (MB). Due to the rough surfaces, the prepared micro-nanoparticles are highly susceptible to the generation of electrons and holes, making them easy to react with H2O2 to promote the degradation, and the different degradation efficiencies of RhB and MB by different crystal forms of CuS are probably caused by the different matching degrees of the molecular structures between dyes and catalysts. Moreover, CuS with different crystal forms degraded the dyes almost completely after being used repeatly for 5 times. Therefore, the as-prepared spherical hexagonal and orthogonal CuS micro-nanoparticles should be potentially used as the effective catalysts for environmental pollution cleanups.

Simultaneous Manufacturing/Structural Shape Optimization for Minimum Product Cost . (Dept. M. ( Production ) )

This paper presents an integrated manufacturing/structural shape optimization method that considers not only structural performance but also machining cost. It explores the tradeoff between mass and machining cost with the application of the end-milling and grinding machining processes to machine and finish a virtual die. The objective function of the integrated optimization problem is the total cost (material & machining). The structural shape is constructed by using B-Splines and hole generation; the design variables are X- and Y-coordinates of the B-Splines control points. The design variables also include the cutting parameters i.e. the cutting speed, the feed rate and the tool diameter. The problem constraints are for both manufacturing and structural shape. The optimization problem will be achieved by interfacing between MATLAB2011aand ANSYS11 programs using Sequential Quadratic Programming (SQP) as a mathematical optimization solver. In this paper, there are three cases of hole generation in the product depending upon the idea of topology optimization. The comparison between the initial total cost and its optimal results for all cases is presented and the influence of the required batch size on the final shape is discussed. It is found that the reduction percentage in the total cost of the virtual die of the last case (i.e. three holes generation) is about 28 % by using SQP algorithm for batch size of 50 pieces after eight iterations and 48% for batch size of 5000 pieces after fourteen iterations. The final optimized shape has also changed as a result of the product batch size demand.

Introduction of multi-particle Büttiker probes—Bridging the gap between drift diffusion and quantum transport

State-of-the-art industrial semiconductor device modeling is based on highly efficient Drift-Diffusion (DD) models that include some quantum corrections for nanodevices. In contrast, latest academic quantum transport models are based on the non-equilibrium Green’s function (NEGF) method that covers all coherent and incoherent quantum effects consistently. Carrier recombination and generation in optoelectronic nanodevices represent an immense numerical challenge when solved within NEGF. In this work, the numerically efficient Büttiker-probe model is expanded to include electron–hole recombination and generation in the NEGF framework. Benchmarks of the new multiple-particle Büttiker probe method against state-of-the-art quantum-corrected DD models show quantitative agreements except in cases of pronounced tunneling and interference effects.

Enhanced near-Infrared Photoresponse from Nanoscale Ag-Au Alloyed Films

Alloying of metals provides a vast parameter space for tuning of material, chemical, and mechanical properties, impacting disciplines ranging from photonics and catalysis to aerospace. From an optical point-of-view, pure thin metal films yield enhanced light absorption due to their cavity effects. However, an ideal metal–semiconductor photodetector requires not only high absorption, but also long hot carrier attenuation lengths in order to efficiently collect excited carriers. Here we demonstrate that Ag-Au alloys provide an ideal model system for controlling the optical and electrical responses in nanoscale thin metal films for hot carrier photodetectors with improved performance. While pure Ag and Au have long hot carrier attenuation lengths >20 nm, their optical absorption is insufficient for high efficiency devices. Instead, we find that alloying Ag and Au enhances the absorption by ∼50% while maintaining attenuation lengths >15 nm, currently limited by grain boundary scattering, although the electron attenuation length of pure Au outperforms pure Ag as well as all of the alloys investigated here. Further, our density functional theory analysis shows that the addition of small amounts of Au to the Ag lattice significantly enhances the hot hole generation rate. Combined, these findings suggest a route to high efficiency hot carrier devices based on metallic alloying with potential applications ranging from photodetectors and sensors to improved catalytic materials.

Generation of primordial black holes and gravitational waves from dilaton-gauge field dynamics

We study the observational signatures from particle production of a U(1) gauge field kinetically coupled to an inflaton. Regarding the form of gauge kinetic function, we consider the possibility that it becomes stabilized at a certain time, which makes the growing power of the gauge field evolve non-monotonically with a sharp transition. Remarkably, the copious production of the gauge field occurs on super-horizon scales at the late stage of inflation and perturbations are enhanced on the intermediate scales during inflation. We find that it can predict a bumpy shape of the curvature power spectrum which leads to the generation of primordial black holes as a dark matter after inflation. We also estimate two types of tensor modes sourced by the gauge field: the primordial gravitational waves generated during inflation and the induced gravitational waves provided by the enhanced curvature perturbation after inflation. We show that both of them are potentially testable with the future space-based gravitational wave interferometers.

Oxygen nonstoichiometry and electrical properties of La2–xSrxNiO4+δ (0 ≤ x ≤ 0.5)

The amount of interstitial oxygen (δ) in Sr-doped lanthanum nickel oxide (La2–xSrxNiO4+δ) as a function of Sr content has been investigated by the thermogravimetry analysis (TGA) and X-ray photoelectron spectroscopy (XPS). La2–xSrxNiO4+δ (0 ≤ x ≤ 0.5) ceramics were prepared by the general solid-state reaction process and sintered in different ambient of argon, air or oxygen, respectively. An increase in the amount of Sr decreased δ in La2–xSrxNiO4+δ, while the Ni2+/Ni3+ ratio analyzed by Ni3p XPS decreased indicating that the oxidation state of Ni increased. Particularly when the sample was sintered in a low oxygen partial pressure condition such as in Ar ambient, the hole concentration strongly depended on the Sr content, suggesting that the hole generation seems mostly originated from Sr2+ substitution into the La3+ site.

Formation of the First Stars and Black Holes

We review the current status of knowledge concerning the early phases of star formation during cosmic dawn. This includes the first generations of stars forming in the lowest mass dark matter halos in which cooling and condensation of gas with primordial composition is possible at very high redshift ($z > 20$), namely metal-free Population III stars, and the first generation of massive black holes forming at such early epochs, the so-called black hole seeds. The formation of black hole seeds as end states of the collapse of Population III stars, or via direct collapse scenarios, is discussed. In particular, special emphasis is given to the physics of supermassive stars as potential precursors of direct collapse black holes, in light of recent results of stellar evolution models, and of numerical simulations of the early stages of galaxy formation. Furthermore, we discuss the role of the cosmic radiation produced by the early generation of stars and black holes at high redshift in the process of reionization.

Recycling of titanium-coagulated algae-rich sludge for enhanced photocatalytic oxidation of phenolic contaminants through oxygen vacancy

In the 21st century, sludge disposal and resource recycling are global issues. Titanium coagulation has received increasing attention due its strong coagulation capability and sludge recycling. Titanium coagulation is highly efficient for the treatment of algae-laden micro-polluted surface water; however, the safe disposal of titanium-coagulated algae-rich sludge remains a challenge. Here, we report on the recycling of titanium-coagulated algae-rich sludge for the production of functional TiO2 nanoflowers (TNFs) through a simple hydrothermal and calcination process. Anatase TNFs (particle size of 10–15 nm) with petal-like structures (mesoporous), relatively high specific surface areas, i.e. 299.4 m2g-1, and low band gaps, i.e. 2.67 eV (compared to P-25), were obtained. Additionally, oxygen vacancy (OV) was generated on the surface of the recycled TNFs based on electron paramagnetic resonance (EPR) results, which were verified by the first-principles calculations within density-functional theory. These TNFs display high photocatalytic performance for the degradation of diverse phenolic organic contaminants, such as bisphenol A, diphenyl phenol, p-tert-butyl phenol, and resorcinol, i.e. > 95%, under mild ultraviolet light irradiation and without any sacrificial reagents. Formation of OV on TNFs not only efficiently inhibited the recombination of photo-generated electrons and holes but also facilitated contaminant adsorption and photo-generated electron transfer on the surface of the recycled TNFs, thereby promoting the generation of holes and hydroxyl and superoxide radicals which were regarded as the reactive oxygen species for attacking contaminants in the reactions. This study proposes a new perspective on recycling chemical-coagulated sludge for producing functional nanomaterials as photocatalysts.

Lateral Vibrations in Deep Hole Drilling Due to Land Width Variation

In drilling processes, self-excited vibrations have a negative influence on the achievable drilling qualities and tool life. Low-frequency radial vibrations are characterised by oscillating movements of the tool tip and the generation of lobed holes in drilling. This study focuses on the participation and influence of the land widths of twisted drilling tools on these vibrations. Therefore, drilling tools with different land widths and a length-to-diameter ratio of 12 are used, and different parameters, such as feed rate, cutting speed, coolant pressure, pre-hole diameter, and chuck selection, are varied in a drill-out process. The results show that the land widths have a statistically significant influence on the formation of lateral vibrations and the generation of lobed holes.

Level set topology and shape optimization by density methods using cut elements with length scale control

The level set and density methods for topology optimization are often perceived as two very different approaches. This has to some extent led to two competing research directions working in parallel with only little overlap and knowledge exchange. In this paper, we conjecture that this is a misconception and that the overlap and similarities are far greater than the differences. To verify this claim, we employ, without significant modifications, many of the base ingredients from the density method to construct a crisp interface level set optimization approach using a simple cut element method. That is, we use the same design field representation, the same projection filters, the same optimizer, and the same so-called robust approach as used in density-based optimization for length scale control. The only noticeable difference lies in the finite element and sensitivity analysis, here based on a cut element method, which provides an accurate tool to model arbitrary, crisp interfaces on a structured mesh based on the thresholding of a level set—or density—field. The presented work includes a heuristic hole generation scheme and we demonstrate the design approach on several numerical examples covering compliance minimization and a compliant force inverter. Finally, we provide our MATLAB code, downloadable from www.topopt.dtu.dk, to facilitate further extension of the proposed method to, e.g., multiphysics problems.

An InGaN/SiNx/Si Uniband Diode

We introduce a diode that operates differently from p–n junction or Schottky diodes. It is based on a p-Si/n-In0.4Ga0.6N heterojunction with a SiNx interlayer. With around 40% In content, the valence and conduction bands of Si and InGaN are aligned. The behavior of the p-Si/n-InGaN interface is ohmic due to electron–hole recombination and generation at forward and reverse bias. Upon insertion of a sufficiently thick SiNx interlayer, the forward current is governed by tunneling. The reverse current is blocked because electron–hole generation is no longer possible together at the interface. A pronounced, weakly temperature-dependent rectifying behavior results.

Effect of annealing temperature on the synthesis and photocatalytic properties of Bi0.65K0.2Ba0.15FeO3 perovskite-like nanoparticle synthesized by sol-gel method

BackgroundBiFeO3 shows promising applications in photocatalytic degradation, purification process, and in clean energy generation. The various fascinating properties of bismuth ferrite nanoparticles can be improved by doping the material at either of the A or B sites to give it extra photocatalytic advantage toward decreasing the energy bandgap and other photophysical properties of the material.ResultsIn this research, pure Bi0.65K0.2Ba0.15FeO3 perovskite material was synthesized using the sol-gel method via citric acid route in the presence of sodium dodecyl sulfate (SDS). The powdered nanoparticles were annealed at different annealing temperatures of 600, 700, and 800 °C each for 4 h in a muffle furnace and coded K2BFO 600, K2BFO 700, and K2BFO 800 corresponding to the annealing temperature of each portion. The powder nanoparticles were characterized using powdered X-ray diffraction (PXRD) to determine the crystallite structure. The samples displayed similar peak patterns with increase in intensity as the annealing temperature is increased indicating an increase in crystallinity. The impurity peaks in K2BFO 800, however, show that the sample may contain a secondary phase. Scanning electron microscopy (SEM) was used to determine the morphology, and UV-Vis spectroscopy indicated that all the powders were photoactive within the visible region of the electromagnetic spectrum. ATR-FTIR spectra of the samples were collected to study the formation and phase purity of the B-site in the perovskite structures. The photocatalytic performance of the powder was tested on methylene blue dye under visible light irradiation for the degradation studies. All powders showed photocatalytic ability after 2 h of irradiation with the powder annealed at 800 °C being better. The photocatalytic activities of the powders showed improvement on addition of 2 drops of 1 M H2O2 (80% degradation for K2BFO 800). The bandgap energy of K2BFO 800, 700, and 600 was estimated at approximately 2.00, 2.12, and 2.18 eV, respectively, using Tauc’s equation. The improved activity is as a result of photoabsorption of visible light by the doped powders causing generation of electrons and holes. The kinetic studies were carried out and the mechanisms of the photocatalytic reaction proposed.ConclusionThe effect of annealing temperature on synthesis of the material shows enhanced photoactivity in the presence of hydrogen peroxide leading to improved performance for the degradation of MB, and the catalyst can be said to be a good candidate for the treatment of waste materials.

Model of the Effect of the Gate Bias on MOS Structures under Ionizing Radiation

A new quantitative model of the effect of the gate bias on the threshold voltage of metal-oxide-semiconductor (MOS) structures under ionizing irradiation is developed based on the consideration of hole trapping from the entire volume of the gate dielectric in a thin boundary layer with hydrogen-free and hydrogen-containing traps at the interface with a silicon substrate. The model makes it possible to adequately describe a gradual increase in the threshold voltage with gate bias as approximately linear with dose for the surface component and nonlinear for the bulk component. The threshold-voltage shift at negative gate bias is simulated based on hole generation in the boundary layer under ionizing irradiation.