Resistive switching behavior and mechanism of HfO_(x) films with large on/off ratio by structure design

Different bilayer structures of HfO_(x)/Ti(TiO_(x)) are designed for hafnium-based memory to investigate the switching characteristics. The chemical states in the films and near the interface are characterized by x-ray photoelectron spectroscopy,and the oxygen vacancies are analyzed. Highly improved on/off ratio(~104) and much uniform switching parameters are observed for bilayer structures compared to single layer HfO_(x) sample, which can be attributed to the modulation of oxygen vacancies at the interface and better control of the growth of filaments. Furthermore, the reliability of the prepared samples is investigated. The carrier conduction behaviors of HfO_(x)-based samples can be attributed to the trapping and de-trapping process of oxygen vacancies and a filamentary model is proposed. In addition, the rupture of filaments during the reset process for the bilayer structures occur at the weak points near the interface by the recovery of oxygen vacancies accompanied by the variation of barrier height. The re-formation of fixed filaments due to the residual filaments as lightning rods results in the better switching performance of the bilayer structure.

Sorbitol-Electrolyte-Additive Based Reversible Zinc Electrochemistry

The unstable zinc(Zn)/electrolyte interfaces formed by undesired dendrites and parasitic side reactions greatly hinder the development of aqueous zinc ion batteries.Herein,the hydroxy-rich sorbitol was used as an additive to reshape the solvation structure and modulate the interface chemistry.The strong interactions among sorbitol and both water molecules and Zn electrode can reduce the free water activity,optimize the solvation shell of water and Zn^(2+)ions,and regulate the formation of local water(H_(2)O)-poor environment on the surface of Zn electrode,which effectively inhibit the decomposition of water molecules,and thus,achieve the thermodynamically stable and highly reversible Zn electrochemistry.As a result,the assembled Zn/Zn symmetric cells with the sorbitol additive realized an excellent cycling life of 2000 h at 1 mA·cm^(-2)and 1 mAh·cm^(-2),and over 250 h at 5 mA.cm^(-2)and 5 mAh.cm^(-2).Moreover,the Zn/Cu asymmetric cells with the sorbitol additive achieved a high Coulombic efficiency of 99.6%,obtaining a better performance than that with a pure 2 mol-L^(-1)ZnSO_(4)electrolyte.And the constructed Zn/poly1,5-naphthalenediamine(PNDA)batteries could be stably discharged for 2300 cycles at 1 A g^(-1)with an excellent capacity retention rate.This result indicates that the addition of 1 mol-L^(-1)non-toxic sorbitol into a conventional ZnSO_(4)electrolyte can successfully protect the Zn anode interface by improving the electrochemical properties of Zn reversible deposition/decomposition,which greatly promotes its cycle performance,providing a new approach in future development of high performance aqueous Zn ion batteries.

Interface modulated electron mobility enhancement in core–shell nanowires

The transport properties of core–shell nanowires(CSNWs)under interface modulation and confinement are investigated based on the atomic-bond-relaxation(ABR)correlation mechanism and Fermi’s golden rule.An analytical expression for the relationship between carrier mobility and interface mismatch strain is derived and the influence of size,shell thickness and alloyed layer on effective mass,band structures,and deformation potential constant are studied.It is found that interface modulation can not only reduce the lattice mismatch to optimize the band alignment,but also participate in the carrier transport for enhancing mobility.Moreover,the underlying mechanism regarding the interface shape dependence of transport properties in CSNWs is clarified.The great enhancement of electron mobility suggests that the interface modulation may become a potential pathway to improving the performance of nanoelectronic devices.

A Component Selection Framework of Cohesion and Coupling Metrics

Component-based software engineering is concerned with the develop-ment of software that can satisfy the customer prerequisites through reuse or inde-pendent development.Coupling and cohesion measurements are primarily used to analyse the better software design quality,increase the reliability and reduced system software complexity.The complexity measurement of cohesion and coupling component to analyze the relationship between the component module.In this paper,proposed the component selection framework of Hexa-oval optimization algorithm for selecting the suitable components from the repository.It measures the interface density modules of coupling and cohesion in a modular software sys-tem.This cohesion measurement has been taken into two parameters for analyz-ing the result of complexity,with the help of low cohesion and high cohesion.In coupling measures between the component of inside parameters and outside parameters.Thefinal process of coupling and cohesion,the measured values were used for the average calculation of components parameter.This paper measures the complexity of direct and indirect interaction among the component as well as the proposed algorithm selecting the optimal component for the repository.The better result is observed for high cohesion and low coupling in compo-nent-based software engineering.

通过介导相分离制备的纳米结构W-Cu基复合材料的性能

The challenge of fabricating nanostructured W–Cu composites by powder metallurgy has been solved by means of modulated phase separation.A hierarchically nanostructured(HN)W–Cu composite was prepared using intermediary Al through sluggish asynchronous phase separation.In addition to a dual network composed of a Cu phase and the W–Cu nanostructure,dense Al-containing nanoprecipitates with a body-centered cubic(bcc)structure are distributed in the W matrix.Compared with a pristine W/Cu interface,the newly formed W/Cu interfaces modulated by Al and the coherent W/Al-containing particle interfaces possess lower energy and enhanced bonding strength due to efficient electron transfer and strong coupling interactions.With a large number of stable heterogeneous interfaces and a“selflocking”geometry,the HN W–Cu composite exhibits excellent resistance against plastic deformation.The combination of the presented composite’s hardness and compressive strength outperforms all other sintered W–Cu composites with the same Cu content.Under a reciprocating sliding load,the reactive Al prevents excessive oxidation.The excellent synergy of the hardness and toughness of the friction-induced surface endows the HN composite with high abrasion resistance.This study provides a new strategy to modulate the structure and energy state of interfaces in metallic composites containing immiscible components in order to achieve high mechanical performance.

Uniform, fast, and reliable CMOS compatible resistive switching memory

Resistive switching random access memory(RRAM) is considered as one of the potential candidates for next-generation memory. However, obtaining an RRAM device with comprehensively excellent performance, such as high retention and endurance, low variations, as well as CMOS compatibility, etc., is still an open question. In this work, we introduce an insert TaO_(x) layer into HfO_(x)-based RRAM to optimize the device performance. Attributing to robust filament formed in the TaO_(x) layer by a forming operation, the local-field and thermal enhanced effect and interface modulation has been implemented simultaneously. Consequently, the RRAM device features large windows(> 10^(3)), fast switching speed(-10 ns), steady retention(> 72h), high endurance(> 10^(8) cycles), and excellent uniformity of both cycle-to-cycle and device-to-device. These results indicate that inserting the TaO_(x) layer can significantly improve HfO_(x)-based device performance, providing a constructive approach for the practical application of RRAM.

Non-Orthogonal Multi-Carrier Transmission for Internet via Satellite

As the important complementary to terrestrial mobile communications, Internet via satellite can extend the coverage of communication and improve the continuity of data services. To build a space-terrestrial integrated communication system is the inevitable trend in the future. Taking into account combination of 5th generation(5G) terrestrial mobile communication system and satellite communication system, it is necessary to evaluate the promising 5G air interface waveform which can be adopted by satellite. In this paper, several non-orthogonal multi-carrier transmission schemes are evaluated and generalized frequency division multiplexing(GFDM) is advised as potential scheme of space-terrestrial integrated communication system. After the overview of GFDM, the implementation of GFDM transceiver is discussed respectively in time-domain and in frequency-domain. By deriving and comparing implementation complexity, GFDM modulation in time-domain is more suitable for satellite communication system. Then the properties of demodulation algorithms are specified. Based on designed pilot subcarriers, a new improved receiving algorithm is proposed in the end of the paper. The improved algorithm solves the problem of inter subcarriers interference(ICI) in matched filtering(MF) receiver and improves the re-ceiving symbol error rate(SER) obviously. The simulation and analysis prove that the proposed algorithm is effective.

Surfactant-metal-organic framework complexes and their derivatives:advances in electrocatalysis

Metal-organic frameworks(MOFs)and their derivatives received more and more attention due to the diverse morphologies,rich porous structures,and tunable metal active sites,which have been widely used in energy-related electrocatalytic reactions.Surfactants,a class of compounds with hydrophilic and hydrophobic portions in the molecular structure,are able to modulate the properties of liquid and solid surfaces.Surfactants play a crucial role in controlling the shape and size of MOFs,which helps optimize electrocatalytic performance,especially in improving the exposure and accessibility of catalytic active sites.In this review,we first outline the types and applications of surfactants.Second,we describe the interface modulation and reaction mechanism of different surfactants during the forming of MOFs and their derivatives.Finally,we discuss the current applications of surfactant-modified MOFs and their derivatives in electrocatalysis.This review provides a better understanding of surfactantassistant structure regulation and electrocatalytic activity study of MOFs and their derivatives.

Enhanced photoresponse of Cu2O/ZnO heterojunction with piezo-modulated interface engineering

The ability to arbitrarily regulate semiconductor interfaces provides the most effective way to modulate the performance of optoelectronic devices. However, less work has been reported on piezo-modulated interface engineering in all-oxide systems. In this paper, an enhanced photoresponse of an all-oxide Cu2O/ZnO heterojunction was obtained by taking advantage of the piezotronic effect. The illumination density-dependent piezoelectric modulation ability was also comprehensively investigated. An 18.6% enhancement of photoresponse was achieved when applying a a-0.88% compressive strain. Comparative experiments confirmed that this enhancement could be interpreted in terms of the band modification induced by interfacial piezoelectric polarization. The positive piezopotential generated at the ZnO side produces an increase in space charge region in Cu2O, thus providing an extra driving force to separate the excitons more efficiently under illumination. Our research provides a promising method to boost the performance of optoelectronics without altering the interface structure and could be extended to other metal oxide devices.