Coupling ferromagnetic ordering electron transfer channels and surface reconstructed active species for spintronic electrocatalysis of water oxidation

Sluggish reaction kinetics of oxygen evolution reaction(OER), resulting from multistep proton-coupled electron transfer and spin constriction, limits overall efficiency for most reported catalysts. Herein, using modeled ZnFe_(2-x)Ni_xO_(4)(0 ≤ x ≤ 0.4) spinel oxides, we aim to develop better OER electrocatalyst through combining the construction of ferromagnetic(FM) ordering channels and generation of highly active reconstructed species. The number of symmetry-breaking Fe–O–Ni structure links to the formation of FM ordering electron transfer channels. Meanwhile, as the number of Ni^(3+)increases, more ligand holes are formed, beneficial for redirecting surface reconstruction. The electro-activated ZnFe_(1.6)Ni_(0.4)O_(4) shows the highest specific activity, which is 13 and 2.5 times higher than that of ZnFe_(2)O_(4) and unactivated ZnFe_(1.6)Ni_(0.4)O_(4), and even superior to the benchmark IrO_(2) under the overpotential of 350 mV. Applying external magnetic field can make electron spin more aligned, and the activity can be further improved to 39 times of ZnFe_(2)O_(4). We propose that intriguing FM exchange-field interaction at FM/paramagnetic interfaces can penetrate FM ordering channels into reconstructed oxyhydroxide layers, thereby activating oxyhydroxide layers as spin-filter to accelerate spin-selective electron transfer. This work provides a new guideline to develop highly efficient spintronic catalysts for water oxidation and other spin-forbidden reactions.

Spectral shift of solid high-order harmonics from different channels in a combined laser field

We investigate theoretically the spectral shift of the high-order harmonic generation(HHG)in ZnO driven by a combined laser field by solving the two-band semiconductor Bloch equations(SBEs)in the velocity gauge.The combined laser field is synthesized by a fundamental laser pulse and its seventh-frequency laser pulse.When the seventh-frequency laser pulse is added to the rising or falling parts of the fundamental laser field,we find that the spectral blueshift or redshift appears,which is due to the unequal contribution of the rising and falling parts in the fundamental laser field to the harmonics.By analyzing the time-dependent conduction band population in k space,we found that,in addition to the tunneling ionization channel,there is also the resonant electron injection channels which is induced by the seventh-frequency laser pulse.The harmonics generated by the different channels show the spectral redshift or the spectral blueshift,respectively.Through analyzing the k-integrated transient conduction band population of the electrons from different channels,we found that if there is a certain delay in the process of the electron excitation,it will lead to the delay in the harmonic emission,which results in the spectral redshift of the harmonics.

A Novel Flash Memory Using Band-to-Band Tunneling Induced Hot Electron Injection to Program

A novel band to band hot electron programming flash memory device,which features programming with high speed,low voltage,low power consumption,large read current and short access time,is proposed.The new memory cell is programmed by band to band tunneling induced hot electron (BBHE) injection method at the drain,and erased by Fowler Nordheim tunneling through the source region.The work shows that the programming control gate voltage can be reduced to 8V,and the drain leakage current is only 3μA/μm.Under the proposed operating conditions,the program efficiency and the read current rise up to 4×10 -4 and 60μA/μm,respectively,and the program time can be as short as 16μs

Bipolar Theory of MOS Field-Effect Transistors and Experiments

The bipolar theory of field-effect transistor is introduced to replace the 55-year-old classic unipolar theory invented by Shockley in 1952 in order to account for the characteristics observed in recent double-gate nanometer silicon MOS field-effect transistors. Two electron and two hole surface channels are simultaneously present in all channel current ranges. Output and transfer characteristics are computed over practical base and gate oxide thicknesses. The bipolar theory corroborates well with experimental data reported recently for FinFETs with metal/silicon and p/n junction source/drain contacts. Single-device realization of CMOS inverter and SRAM memory circuit functions are recognized.

The Bipolar Field-Effect Transistor:Ⅰ.Electrochemical Current Theory(Two-MOS-Gates on Pure-Base)

This paper describes the bipolar field-effect transistor （BiFET） and its theory. Analytical solution is ob- tained from partitioning the two-dimensional transistor into two one-dimensional transistors. The analysis employs the parametric surface-electric-potential and the electrochemical （quasi-Fermi） potential-gradient driving force to compute the current. Output and transfer D. C. current and conductance versus voltage are presented over practi- cal ranges of terminal D. C. voltages and device parameters. Electron and hole surface channel currents are pres- ent simultaneously, a new feature which could provide circuit functions in one physical transistor such as the CMOS inverter and SRAM memory.

The Bipolar Field-Effect Transistor: III.Short Channel Electrochemical Current Theory (Two-MOS-Gates on Pure-Base)

This paper describes the short channel theory of the bipolar field-effect transistor （BiFET） by partitioning the transistor into two sections,the source and drain sections,each can operate as the electron or hole emitter or collector under specific combinations of applied terminal voltages. Analytical solution is obtained in the source and drain sections by separating the two-dimensional trap-free Shockley Equations into two one-dimensional equations parametrically coupled via the surface-electric-potential and by using electron current continuity and hole current continuity at the boundary between the emitter and collector sections. Total and electron-hole-channel components of the output and transfer currents and conductances, and the electrical lengths of the two sections are computed and presented in graphs as a function of the D. C. terminal voltages for the model transistor with two identical and connected metal-oxide-silicon-gates （MOS-gates） on a thin pure-silicon base over practical ranges of thicknesses of the silicon base and gate oxide. Deviations of the long physical channel currents and conductances from those of the short electrical channels are reported.

The Bipolar Field-Effect Transistor:II.Drift-Diffusion Current Theory(Two-MOS-Gates on Pure-Base)

This paper describes the drift-diffusion theory of the bipolar field-effect transistor （BiFET） with two identical and connected metal-oxide-silicon-gates （MOS-gates） on a thin-pure-base. Analytical solution is obtained by partitioning the two-dimensional transistor into two one-dimensional problems coupled by the parametric sur- face-electric-potential. Total and component output and transfer currents and conductances versus D. C. voltages from the drift-diffusion theory, and their deviations from the electrochemical （quasi-Fermi） potential-gradient theory,are presented over practical ranges of thicknesses of the silicon base and gate oxide. A substantial contri- bution from the longitudinal gradient of the square of the transverse electric field is shown.

The Bipolar Field-Effect Transistor:Ⅳ.Short Channel Drift-Diffusion Current Theory(Two-MOS-Gates on Pure-Base)

This paper gives the short channel analytical theory of the bipolar field-effect transistor （BiFET） with the drift and diffusion currents separately computed in the analytical theory. As in the last-month paper which represented the drift and diffusion current by the single electrochemical （potential-gradient） current, the two-dimensional transistor is partitioned into two sections, the source and drain sections, each can operate as the electron or hole emitter or collector under specific combinations of applied terminal voltages. Analytical solution is then obtained in the source and drain sections by separating the two-dimensional trap-free Shockley Equations into two one-dimensional equations parametrically coupled via the surface-electric-potential and by using electron current continuity and hole current continuity at the boundary between the emitter and collector sections. Total and the drift and diffusion components of the electron-channel and hole-channel currents and output and transfer conductances, and the electrical lengths of the two sections are computed and presented in graphs as a function of the D. C. terminal voltages for the model transistor with two identical and connected metal-oxide-silicon-gates （MOS-gates） on a thin pure-silicon base over practical ranges of thicknesses of the silicon base and gate oxide. Deviations of the two-section short-channel theory from the one-section long-channel theory are described.

The Theory of Field-Effect Transistors:XI. The Bipolar Electrochemical Currents(1-2-MOS-Gates on Thin-Thick Pure-Impure Base)

The field-effect transistor is inherently bipolar, having simultaneously electron and hole surface and volume channels and currents. The channels and currents are controlled by one or more externally applied transverse electric fields. It has been known as the unipolar field-effect transistor for 55-years since Shockley＇s 1952 invention,because the electron-current theory inevitably neglected the hole current from over-specified internal and boundary conditions, such as the electrical neutrality and the constant hole-electrochemical-potential, resulting in erroneous solutions of the internal and terminal electrical characteristics from the electron channel current alone, which are in gross error when the neglected hole current becomes comparable to the electron current, both in subthreshold and strong inversion. This report presents the general theory, that includes both electron and hole channels and currents. The rectangular （ x, y, z） parallelepiped transistors,uniform in the width direction （z-axis）,with one or two MOS gates on thin and thick,and pure and impure base, are used to illustrate the two-dimensional effects and the correct internal and boundary conditions for the electric and the electron and hole electrochemical potentials. Complete analytical equations of the DC current-voltage characteristics of four common MOS transistor structures are derived without over-specification： the 1-gate on semi-infinite-thick impure-base （the traditional bulk transistor）, the 1-gate on thin impure-silicon layer over oxide-insulated silicon bulk （SOI） ,the 1-gate on thin impure-silicon layer deposited on insulating glass （SOI TFT）, and the 2-gates on thin pure-base （FinFETs）.

Hydrogen effect on the mechanical behaviour and microstructural features of a Fe-Mn-C twinning induced plasticity steel

The influences of hydrogen on the mechanical properties and the fracture behaviour of Fe-22Mn-0.6C twinning induced plasticity steel have been investigated by slow strain rate tests and fractographic analysis.The steel showed high susceptibility to hydrogen embrittlement,which led to 62.9%and 74.2%reduction in engineering strain with 3.1 and 14.4 ppm diffusive hydrogen,respectively.The fracture surfaces revealed a transition from ductile to brittle dominated fracture modes with the rising hydrogen contents.The underlying deformation and fracture mechanisms were further exploited by examining the hydrogen effects on the dislocation substructure,stacking fault probability,and twinning behaviour in pre-strained slow strain rate test specimens and notched tensile specimens using coupled electron channelling contrast imaging and electron backscatter diffraction techniques.The results reveal that the addition of hydrogen promotes planar dislocation structures,earlier nucleation of stacking faults,and deformation twinning within those grains which have tensile axis orientations close to<111>//rolling direction and<112>//rolling direction.The developed twin lamellae result in strain localization and micro-voids at grain boundaries and eventually lead to grain boundary decohesion.

Bimetal MOF-derived NiFe-P nanocomposites coupled with Cu_(3)P nanoparticles to construct tandem electron transfer channels for photocatalytic hydrogen evolution

Finely modulated light-induced charge separation and transfer is a central challenge to achieve efficient photocatalysis.Although progress has been made in this field,most of the previous research works focused on the separation or migration of photogenerated carriers but did not build a bridge between the two.How to realize the strong driving and precise migration of carriers has become the focus of our work.We report an ingeniously designed ternary heterojunction.Taking NiFe-MOF as the“parent material”,the FeP_(4)/Ni_(x)P_(y)heterojunction is derived in situ while maintaining the frame structure through gas-solid reaction,and finally the Z-type electron transfer is realized.With Cu_(3)P anchoring spindle matrix,an electron transport tunnel is opened up in Cu_(3)P/FeP_(4)/Ni_(x)P_(y)ternary heterojunction under the action of p-n heterojunction built-in electric field driving and accurate energy band matching.The strong driving force of the built-in electric field provides an inexhaustible power for the transmission of electrons,and the fine series of electron transmission channels realizes the precise transmission of electrons.The above fine design makes the perfect fit between the built-in electric field and the electron transfer channel,which not only effectively improves the embarrassing situation of insufficient electron driving force of hydrogen evolution reaction in the previous research,but also makes up for the weakening of semi-conductor reduction ability caused by the construction of traditional p-n heterostructures.This research work provides a new idea for the construction of multiple heterostructures and the design of fine interface engineering in the future.

Degradation of gate-recessed MOS-HEMTs and conventional HEMTs under DC electrical stress

The performance degradation of gate-recessed metal–oxide–semiconductor high electron mobility transistor(MOSHEMT)is compared with that of conventional high electron mobility transistor(HEMT)under direct current(DC)stress,and the degradation mechanism is studied.Under the channel hot electron injection stress,the degradation of gate-recessed MOS-HEMT is more serious than that of conventional HEMT devices due to the combined effect of traps in the barrier layer,and that under the gate dielectric of the device.The threshold voltage of conventional HEMT shows a reduction under the gate electron injection stress,which is caused by the barrier layer traps trapping the injected electrons and releasing them into the channel.However,because of defects under gate dielectrics which can trap the electrons injected from gate and deplete part of the channel,the threshold voltage of gate-recessed MOS-HEMT first increases and then decreases as the conventional HEMT.The saturation phenomenon of threshold voltage degradation under high field stress verifies the existence of threshold voltage reduction effect caused by gate electron injection.

AlGaN Channel High Electron Mobility Transistors with an AlxGa1-xN/GaN Composite Buffer Layer

We report an AlGaN channel high electron mobility transistor （HEMT） on a sapphire substrate with a 1000-nm A1xGa1-xN （x = 0-0.18）/GaN composite buffer layer, With a significant improvement of crystal quality, the device features a high product orris. #n. The AIGaN channel HEMTs presented show improved performance with respect to the conventional AIGaN channel HEMTs, including the on-resistance reduced from 31.2 to 8.1 Ω.mm, saturation drain current at 2 V gate bias promoted from 218 to 540 mA/mm, peak transconductance at 10 V drain bias promoted from 100 to a state-of-the-art value of 174 mS/ram, and reverse gate leakage current reduced from 1.85 × 10-3 to 2.15 × 10-5 mA/mm at VOD = -20 V.

A benzo[ghi]-perylene triimide based double-cable conjugated polymer for single-component organic solar cells

Single-component organic solar cells(SCOSCs)with high stability and simplified fabrication process are supposed to accelerate the commercialization of organic photovoltaics.However,the types of photo-active materials and photovoltaic performance of SCOSCs are still far lagging behind the bulk-heterojunction type organic solar cells(BHJ OSCs).It is still an arduous task to introduce new photo-active materials into SCOSCs,aiming to improve the efficiencies of SCOSCs.One feasible way is to construct double-cable polymers with new structures and tune conformation,morphology and mobility for the improvement in power conversion efficiencies(PCEs).Hence,in this work,we constructed a new double-cable polymer PBTT-BPTI by introducing fused core 5,7-dibromo-2,3-bis(2-ethylhexyl)benzo[1,2-b:4,5-c’]dithiophene-4,8-dione(TTDO)into the main backbone and benzo[ghi]-perylene triimide(BPTI)unit into the side chain.Both of the two units show strong electron-withdrawing property,which are expected to broaden absorption spectra and enhance intermolecular interaction.The double-cable polymer exhibited a broad absorption in the range of 300-700 nm with an optical band gap(E_(g))of 1.79 eV.The PCE of PBTT-BPTI-based SCOSCs was 2.15%,which may be limited by the unconstructed efficient electron transporting channels.

Efficient removal for multiple pollutants via Ag_(2)O/BiOBr heterojunction:A promoted photocatalytic process by valid electron transfer pathway

Multiple pollutants including pathogenic microorganism contaminations and emerging organic contaminations(EOCs)have shown a growing threat to the environment,especially the natural waters.However,the control and removal of pathogenic microorganism contaminations and EOCs have been greatly limited since limited knowledge of their environmental behaviors.Thus,a novel and efficient photocatalyst Ag_(2)O/BiOBr heterojunction was synthesized and used for removal of multiple pollutants including Escherichia coli(E.coli),Staphylococcus aureus(S.aureus),tetracycline and acetaminophen under visible light.The results showed that there were valid electron transfer pathways between BiOBr and Ag_(2)O,the main electron transfer direction was the BiOBr to Ag_(2)O.Photo-generated electrons were stored in Ag_(2)O and thus separation efficiency between holes and photo-generated electrons was obviously enhanced.Active oxygen species were highly produced and eventually end up with the high efficiency of removal of multiple pollutants.For Ag_(2)O/BiOBr with Ag_(2)O content at 3%(the best performance)under visible light,log decrease of E.coli was 7.16(removal efficiency was 100%)in 120 min,log decrease of S.aureus was 7.23(removal efficiency was 100%)in 160 min,C/C0 of tetracycline was 0.06 in 180 min,C/C0 of acetaminophen was 0.17 in 180 min.This work could provide a promising candidate in the actual contaminated natural waters for cleaning multiple pollutants.

Observation of the Hydrogen-Dislocation Interactions in a High-Manganese Steel after Hydrogen Adsorption and Desorption

Hydrogen embrittlement(HE)poses a significant challenge for the development of high-strength metallic materials.However,explanations for the observed HE phenomena are still under debate.To shed light on this issue,here we investigated the hydrogen-defect interaction by comparing the dislocation structure evolution after hydrogen adsorption and desorption in a Fe-28Mn-0.3C(wt%)twinning-induced plasticity steel with an austenitic structure using in situ electron channeling contrast imaging.The results indicate that hydrogen can strongly affect dislocation activities.In detail,hydrogen can promote the formation of stacking faults with a long dissociation distance.Besides,dislocation movements are frequently observed during hydrogen desorption.The required resolved shear stress is considered to be the residual stresses rendered by hydrogen segregation.Furthermore,the microstructural heterogeneity could lead to the discrepancy of dislocation activities even within the same materials.

Evaluation of hydrogen effect on the fatigue crack growth behavior of medium-Mn steels via in-situ hydrogen plasma charging in an environmental scanning electron microscope

Fatigue crack growth(FCG)tests were conducted on a medium-Mn steel annealed at two intercritical annealing temperatures,resulting in different austenite(γ)to fe rrite(α)phase fractions and differentγ(meta-)stabilities.Novel in-situ hydrogen plasma charging was combined with in-situ cyclic loading in an environmental scanning electron microscope(ESEM).The in-situ hydrogen plasma cha rging increased the fatigue crack growth rate(FCGR)by up to two times in comparison with the reference tests in vacuum.Fractographic investigations showed a brittle-like crack growth or boundary cracking manner in the hydrogen environment while a ductile transgranular manner in vacuum.For both materials,the plastic deformation zone showed a reduced size along the hydrogen-influenced fracture path in comparison with that in vacuum.The difference in the hydrogen-assisted FCG of the medium-Mn steel with different microstructures was explained in terms of phase fraction,phase stability,yielding strength and hydrogen distribution.This refined study can help to understand the FCG mechanism without or with hydrogen under in-situ hydrogen charging conditions and can provide some insights from the applications point of view.

Axial electron channeling statistical method of site occupancy determination

Multibeams dynamical theory of electron diffraction has been used to calculate the fast electron thickness-integrated probability density on Ti and Al sites in the γ-TiAl phase as a function of the incident electron beam orientation along \[100\], \[110\] and \[011\] zone axes, with the effect of absorption considered. Both of the calculation and experiments show that there are big differences in electron channeling effect for different zone axes or the same axis but with different orientations, so we should choose proper zone axis and suitable incident beam tilting angles when using the axial electron channeling statistical method to determine the site occupancies of impurities. It is suggested to calculate the channeling effect map before the experiments.

Experimental study of channel electron multiplier

Background Channel electron multiplier(CEM)can be used to measure extremely few charged particles,such as electrons and ions.The CEM is widely used in particle detection,so it is very important to study their performance parameters.Purposes Test and analyze the performance parameters of the CEM,such as resistance,gain,and pulse output for a single entrance photoelectron.Methods The heated tantalum filament is used as a stable and adjustable planar electron source to test the performance of the CEM in the analog mode.The performance parameters of the CEM in the pulse counting mode are tested by using the ultraviolet LED to excite the gold photocathode to generate a single photoelectron.Results and conclusions The gain of the CEM in the analog mode can reach more than 106 and the gain in the pulse counting mode can be two orders of magnitude higher.The curved helical channel has a greater advantage than the ordinary straight channel,which is conducive to weakening the ion feedback phenomenon.

The Bipolar Field-Effect Transistor:XⅢ. Physical Realizations of the Transistor and Circuits(One-Two-MOS-Gates on Thin-Thick Pure-Impure Base)

This paper reports the physical realization of the Bipolar Field-Effect Transistor （BiFET） and its onetransistor basic building block circuits. Examples are given for the one and two MOS gates on thin and thick, pure and impure base, with electron and hole contacts, and the corresponding theoretical current-voltage characteristics previously computed by us, without generation-recombination-trapping-tunneling of electrons and holes. These examples include the one-MOS-gate on semi-infinite thick impure base transistor （the bulk transistor） and the impurethin-base Silicon-on-Insulator （SOI） transistor and the two-MOS-gates on thin base transistors （the FinFET and the Thin Film Transistor TFF）. Figures are given with the cross-section views containing the electron and hole concentration and current density distributions and trajectories and the corresponding DC current-voltage characteristics.