查看更多>>摘要：Hafnium zirconium oxides(HZO),which exhibit ferroelectric properties,are promising materials for nanoscale device fabrication due to their high complementary metal-oxide-semiconductor(CMOS)compatibility.In addition to piezoelec-tricity,ferroelectricity,and flexoelectricity,this study reports the observation of ferroelasticity using piezoelectric force microscopy(PFM)and scanning transmission electron microscopy(STEM).The dynamics of 90° ferroelastic domains in HZO thin films are investigated under the influence of an electric field.Switching of the retentive domains is observed through repeated wake-up measurements.This study presents a possibility of enhancing polarization in HZO thin films during wake-up processes.
查看更多>>摘要：Perpendicular optical reversal of the linear dichroism transition has promising applications in polarization-sensitive optoelectronic devices.We perform a systematical study on the in-plane optical anisotropy of quasi-one-dimensional PdBr2 by using combined measurements of the angle-resolved polarized Raman spectroscopy(ARPRS)and anisotropic opti-cal absorption spectrum.The analyses of ARPRS data validate the anisotropic Raman properties of the PdBr2 flake.And anisotropic optical absorption spectrum of PdBr2 nanoflake demonstrates distinct optical linear dichroism rever-sal.Photodetector constructed by PdBr2 nanowire exhibits high responsivity of 747 A·W-1 and specific detectivity of 5.8×1012 Jones.And the photodetector demonstrates prominent polarization-sensitive photoresponsivity under 405-nm light irradiation with large photocurrent anisotropy ratio of 1.56,which is superior to those of most of previously reported quasi-one-dimensional counterparts.Our study offers fundamental insights into the strong optical anisotropy exhibited by PdBr2,establishing it as a promising candidate for miniaturization and integration trends of polarization-related applica-tions.
查看更多>>摘要：The regulating nitrogen content of diamond in a hydrogen-rich high-temperature and high-pressure(HPHT)growth environment was systematically investigated in this work by developing three growth systems,namely,"FeNi+Ti","FeNi+C3N6H6",and"FeNi+Ti+C3N6H6".Optical microscopy,infrared spectroscopy,and photoluminescence(PL)spectroscopy measurements were conducted to analyze the spectroscopic characteristics of diamonds grown in these three systems.From our analysis,it was demonstrated that the presence of hydrogen in the sp3 hybrid C-H does not directly affect the color of the diamond and facilitates the increase of the nitrogen-vacancy(NV)center concentration in a high-nitrogen-content diamond.In addition,titanium plays an important role in nitrogen removal,while its impact on hydrogen doping within the diamond lattice is insignificant.Most importantly,by regulating the ratio of nitrogen impurities that coexist in the nitrogen and hydrogen HPHT environment,the production of hydrogenous Ⅱa-type diamond,hydrogenous Ib-type diamond,and hydrogenous high-nitrogen-type diamonds was achieved with a nitrogen content of less than 1 ppm to 1600 ppm.
查看更多>>摘要：Titanium nitride films are prepared by plasma enhanced chemical vapor deposition method on titanium foil using N2 as precursor.In order to evaluate the effect of oxygen on the growth of titanium nitride films,a small amount of O2 is introduced into the preparation process.The study indicates that trace O2 addition into the reaction chamber gives rise to significant changes on the color and micro-morphology of the foil,featuring dense and long nano-wires.The as-synthesized nanostructures are characterized by various methods and identified as TiN,Ti2N,and TiO2 respectively.Moreover,the experiment results show that oxide nanowire has a high degree of crystallinity and the nitrides present specific orientation relationships with the titanium matrix.
查看更多>>摘要：Magnetic metals deposited on graphene hold the key to applications in spintronics.Here,we present the results of Fe islands grown on graphene/SiC(0001)by molecular beam epitaxy,which are investigated by scanning tunneling microscopy.The two types of islands distinguished by flat or round tops are revealed,indicating bimodal growth of Fe.The atomic structures on the top surfaces of flat islands are also clearly resolved.Our results may improve the understanding of the mechanisms of metals deposited on graphene and pave the way for future spintronic applications of Fe/graphene systems.
查看更多>>摘要：An abnormally high peak friction angle of Ottawa sand was observed in(National Aeronautics and Space Adminis-tration)NASA-(Mechanics of Granular Materials)MGM tests in microgravity conditions on the space shuttle.Previous investigations have been unsuccessful in providing a constitutive insight into this behavior of granular materials under extremely low effective stress conditions.Here,a recently proposed unified constitutive model for transient rheological behavior of sand and other granular materials is adopted for the analytical assessment of high peak friction angles.For the first time,this long-eluded behavior of sand is attributed to a hidden rheological transition mechanism,that is not only rate-sensitive,but also pressure-sensitive.The NASA-MGM microgravity conditions show that shear-tests of sand can be performed under abnormally low confining stress conditions.The pressure-sensitive behavior of granular shearing that is previously ignored is studied based on the μ(I)rheology and its variations.Comparisons between the model and the NASA microgravity tests demonstrate a high degree of agreement.The research is highly valid for pressure-sensitive and rate-dependent problems that occur during earthquakes,landslides,and space exploration.
查看更多>>摘要：Artificial neural networks(ANN)have been extensively researched due to their significant energy-saving benefits.Hardware implementations of ANN with dropout function would be able to avoid the overfitting problem.This letter reports a dropout neuronal unit(1R1T-DNU)based on one memristor-one electrolyte-gated transistor with an ultralow energy consumption of 25 pJ/spike.A dropout neural network is constructed based on such a device and has been verified by MNIST dataset,demonstrating high recognition accuracies(≥ 90％)within a large range of dropout probabilities up to 40％.The running time can be reduced by increasing dropout probability without a significant loss in accuracy.Our results indicate the great potential of introducing such IRIT-DNUs in full-hardware neural networks to enhance energy efficiency and to solve the overfitting problem.
查看更多>>摘要：The selection of photoactive layer materials for organic solar cells(OSCs)is essential for the photoelectric conversion process.It is well known that chlorophyll is an abundant pigment in nature and is extremely valuable for photosynthesis.However,there is little research on how to improve the efficiency of chlorophyll-based OSCs by matching chlorophyll derivatives with excellent non-fullerene acceptors to form heterojunctions.Therefore in this study we utilize a chlorophyll derivative,Ce6Me3,as a donor material and investigate the performance of its heterojunction with acceptor materials.Through density functional theory,the photoelectric performances of acceptors,including the fullerene derivative PC71BM and the terminal halogenated non-fullerene DTBCIC series,are compared in detail.It is found that DTBCIC-C1 has better planarity,light absorption,electron affinity,charge reorganization energy and charge mobility than others.Ce6Me3 has good energy level matching and absorption spectral complementarity with the investigated acceptor molecules and also shows good electron donor properties.Furthermore,the designed Ce6Me3/DTBCIC interfaces have improved charge separation and reorganization rates(KCS/KCR)compared with the Ce6Me3/PC71BM interface.This research provides a theoretical basis for the design of photoactive layer materials for chlorophyll-based OSCs.
查看更多>>摘要：To protect superconducting qubits and enable rapid readout,optimally designed Purcell filters are essential.To sup-press the off-resonant driving of untargeted readout resonators,individual Purcell filters are used for each readout resonator.However,achieving consistent frequency between a readout resonator and a Purcell filter is a significant challenge.A sys-tematic computational analysis is conducted to investigate how fabrication variation affects filter performance,through fo-cusing on the coupling capacitor structure and coplanar waveguide(CPW)transmission line specifications.The results indi-cate that the T-type enclosing capacitor(EC),which exhibits lower structural sensitivity,is more advantageous for achieving target capacitance than the C-type EC and the interdigital capacitor(IDC).By utilizing a large-sized CPW with the T-type EC structure,fluctuations in the effective coupling strength can be reduced to 10％,given typical micro-nanofabrication variances.The numerical simulations presented in this work minimize the influence of fabrication deviations,thereby significantly improving the reliability of Purcell filter designs.
查看更多>>摘要：Topological zero-line modes(ZLMs)with spin and valley degrees of freedom give rise to spin,valley and spin-valley transport,which support a platform for exploring quantum transport physics and potential applications in spin-tronic/valleytronic devices.In this work,we investigate the beam-splitting behaviors of the charge current due to the ZLMs in a three-terminal system.We show that with certain combinations of ZLMs,the incident charge current along the inter-face between different topological phases can be divided into different polarized currents with unit transmittance in two outgoing terminals.As a result,fully spin-polarized,valley-polarized and spin-valley-polarized electron beam splitters are generated.The mechanism of these splitters is attributed to the cooperative effects of the distribution of the ZLMs and the intervalley and intravalley scatterings that are modulated by the wave-vector mismatch and group velocity mismatch.In-terestingly,half-quantized transmittance of these scatterings is found in a fully spin-valley-polarized electron beam splitter.Furthermore,the results indicate that these splitters can be applicable to graphene,silicene,germanene and stanene due to their robustness against the spin-orbit coupling.Our findings offer a new way to understand the transport mechanism and investigate the promising applications of ZLMs.
NETL
NSTL
万方数据