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Sputter-Deposited-MoS2 nMISFETs with Top-Gate and Al2O3 Passivation under Low Thermal Budget for Large Area Integration
摘要： We have fabricated large area integrated top-gate nMISFETs with sputter-deposited-MoS2 film having n-type operation. A sputtering method enables us to form a large-area MoS2 thin film followed by H2S annealing to compensate sulfur vacancies. Two passivation films of ALD-Al2O3 enhance the process endurance of MoS2 channel. Therefore, we demonstrate TiN-top-gate nMISFET, which is a substantial first step to realize industrial chip-level LSIs with MoS2-channel FETs.
关键词： Top gate,MISFET,Transition metal di-chalcogenide,Sputtering,Passivation,Molybdenum disulfide,Large area integration
更新于2025-09-23 15:21:21
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Novel Biodegradable Polymer Tethered Platinum (II) for Photoacoustic Imaging
摘要： Photoacoustic microscopy (PAM) is an emerging imaging diagnostic technique for various diseases. Coupled with contrast agents, photoacoustic (PA) imaging yields additional information to facilitate an accurate diagnosis. While many organic-based contrast agents, notably those of cyanine dyes, nanoparticles, polyhydroxy-fullerene and carbon nanotubes, have become available, the use of transition metal as contrast agent is scant. Here, for the first time, we report a platinum II-based biodegradable polymer for PA imaging that is capable of effective cellular internalization with very low cytotoxicity. The experiment results show great promise as a novel photoacoustic contrast agent as its detectable PA signal was observed both in cell imaging and in vivo rat cerebral vascular imaging via designed PAM. This work exemplifies the incorporation of transition metal complex with polymeric nanoparticles, further expanding the field of the ability of PA imaging.
关键词： Platinum,Biodegradable polymer,Photoacoustic imaging,Contrast agent,Transition metal
更新于2025-09-23 15:21:21
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Synthesis and Spectroscopic Investigations of Schiff Bases Transition Metal Complexes of Copper(II), Cobalt(II) and Nickel(II)
摘要： This work presents an experimental and theoretical study on complexes of copper(II), cobalt(II) and nickel(II) with Schiff base ligand 3-propyl-(N-o-toluidine)quinazoline semicarbazone (PTQS). The spectroscopic properties of the complexes have been investigated by IR and electronic spectra. The molecular geometry of the complexes have been proposed on the basis of elemental analyses, molar mass and magnetic susceptibility. It is suggested that the ligand PTQS acts in a bidentate manner and coordination proposes with azomethine N and carbonyl oxygen atom of semicarbazone moiety. The remaining coordination sites are occupied by negative ions such as Cl?, Br?, I?, NO3? and ClO4?. The geometry of complexes was assigned to be octahedral.
关键词： Transition metal(II) complexes,Semicarbazone,3-Propyl-(N-o-toludine)quinazoline,Schiff base
更新于2025-09-23 15:21:21
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Can one introduce long range ferromagnetism by doping transition metal in wide band gap semiconducting ZnO?
摘要： In this report, we present a systematic study of magnetic behavior of transition metal (TM = Fe or Cu) doped ZnO and co-doped (Cu, Fe) ZnO nanoparticles. All the samples show antiferromagnetic (AFM) like inverse susceptibility at low temperatures. In all the samples AFM Curie-Weiss temperature TAF M increases with increase in TM ion concentration indicating enhanced antiferromagnetic correlation upon TM doping. We observe a crossover from antiferromagnetic correlation state to ferromagnetic correlation around temperature (T) 100 - 150K. We shall try to explain all the experimental observations by invoking the role of oxygen vacancies, valency of transition metal ions, formation and interaction between bound magnetic polaron (BMP) and their melting in ZnO matrix. Even though we observe ferromagnetic correlation around room temperature in all these samples from the inverse magnetic susceptibility data, but no true long range ferromagnetic transition was observed in magnetization down to lowest measured temperature of 5K. Our study indicates the di?culties in achieving long range ferromagnetism arising due to the formation of BMPs upon lowering the temperature where these BMPs get antiferromagnetically correlated due to superexchange interaction occurring in transition metal doped wide band gap semiconducting ZnO matrix.
关键词： Dilute magnetic semiconductor,Bound magnetic polaron,Antiferromagnetism,Transition metal doping,ZnO,Ferromagnetism
更新于2025-09-23 15:21:21
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Moire intralayer excitons in a MoSe <sub/>2</sub> /MoS <sub/>2</sub> heterostructure
摘要： Spatially periodic structures with a long range period, referred to as moir′e pattern, can be obtained in van der Waals bilayers in the presence of a small stacking angle or of lattice mismatch between the monolayers. Theoretical predictions suggest that the resulting spatially periodic variation of the band structure modifies the optical properties of both intra and interlayer excitons of transition metal dichalcogenides heterostructures. Here, we report on the impact of the moir′e pattern formed in a MoSe2/MoS2 heterobilayer encapsulated in hexagonal boron nitride. The periodic in-plane potential results in a splitting of the MoSe2 exciton and trion in both emission and absorption spectra. The observed energy difference between the split peaks is fully consistent with theoretical predictions.
关键词： valley polarization,van der Waals heterostructures,moir′e pattern,moir′e excitons,Transition metal dichalcogenides
更新于2025-09-23 15:21:21
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Van der Waals junction field effect transistors with both n- and p-channel transition metal dichalcogenides
摘要： Two-dimensional (2D) transition metal dichalcogenides (TMDs)-based van der Waals (vdW) PN junctions have been used for heterojunction diodes, which basically utilize out-of-plane current across the junction interface. In fact, the same vdW PN junction structure can be utilized for another important device application, junction field effect transistors (JFETs), where in-plane current is possible along with 2D–2D heterojunction interface. Moreover, the 2D TMD-based JFET can use both p- and n-channel for low voltage operation, which might be its unique feature. Here we report vdW JFETs as an in-plane current device with heterojunction between semiconducting p- and n-TMDs. Since this vdW JFET would have low-density traps at the vdW interface unlike 2D TMD-based metal insulator semiconductor field effect transistors (MISFETs), little hysteresis of 0.0–0.1 V and best subthreshold swing of ~100 mV/dec were achieved. Easy saturation was observed either from n-channel or p-channel JFET as another advantage over 2D MISFETs, exhibiting early pinch-off at ~1 V. Operational gate voltage for threshold was near 0 V and our highest mobility reaches to ~>500 cm2/V·s for n-channel JFET with MoS2 channel. For 1 V JFET operation, our best ON/OFF current ratio was observed to be ~104.
关键词： n-channel,field effect transistors,van der Waals junction,transition metal dichalcogenides,p-channel
更新于2025-09-23 15:21:21
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A Density Functional Theory Study on Nonlinear Optical Properties of Double Cage Excess Electron Compounds: Theoretically Design M[Cu(Ag)@(NH <sub/>3</sub> ) <sub/><i>n</i> </sub> ](M?=?Be, Mg and Ca; <i>n</i> ?=?1-3)
摘要： In this work, we investigated the nonlinear optical (NLO) properties of excess electron electride molecules of M[Cu(Ag)@(NH3)n] (M = Be, Mg and Ca; n = 1–3) using density functional theory (DFT). This electride molecules consist of an alkaline-earth (Be, Mg and Ca) together with transition metal (Cu and Ag) doped in NH3 cluster. The natural population analysis of charge and their highest occupied molecular orbital suggests that the M[Cu(Ag)@(NH3)n] compound has excess electron like alkaline-earth metal form double cage electrides molecules, which exhibit a large static ?rst hyperpolarizability (βe0) and one of which owns a peak value of βe0 216,938 (a.u.) for Be[Ag@(NH3)2] and vibrational harmonic ?rst hyperpolarizability.
关键词： NLO,transition metal,alkaline-earth,DFT,double cage excess electron compounds
更新于2025-09-23 15:21:21
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Quasi-1D TiS <sub/>3</sub> Nanoribbons: Mechanical Exfoliation and Thickness-Dependent Raman Spectroscopy
摘要： Quasi-one-dimensional (quasi-1D) materials enjoy growing interest due to their unusual physical properties and promise for miniature electronic devices. However, the mechanical exfoliation of quasi-1D materials into thin flakes and nanoribbons received considerably less attention from researchers than the exfoliation of conventional layered crystals. In this study, we investigated the micromechanical exfoliation of representative quasi-1D crystals, TiS3 whiskers, and demonstrate that they typically split into narrow nanoribbons with very smooth, straight edges and clear signatures of 1D TiS3 chains. Theoretical calculations show that the energies required for breaking weak interactions between the two-dimensional (2D) layers and between 1D chains within the layers are comparable and, in turn, are considerably lower than those required for breaking the covalent bonds within the chains. We also emulated macroscopic exfoliation experiments on the nanoscale by applying a local shear force to TiS3 crystals in different crystallographic directions using a tip of an atomic force microscopy (AFM) probe. In the AFM experiments, it was possible to slide the 2D TiS3 layers relative to each other as well as to remove selected 1D chains from the layers. We systematically studied the exfoliated TiS3 crystals by Raman spectroscopy and identified the Raman peaks whose spectral positions were most dependent on the crystals’ thickness. These results could be used to distinguish between TiS3 crystals with thickness ranging from one to about seven monolayers. The conclusions established in this study for the exfoliated TiS3 crystals can be extended to a variety of transition metal trichalcogenide materials as well as other quasi-1D crystals. The possibility of exfoliation of TiS3 into narrow (few-nm wide) crystals with smooth edges could be important for the future realization of miniature device channels with reduced edge scattering of charge carriers.
关键词： transition metal trichalcogenides,quasi-one-dimensional materials,scanning near-field optical microscopy,Raman spectroscopy,mechanical exfoliation
更新于2025-09-23 15:21:21
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Optimization of synthesis condition of water-resistant and thin titanium oxide layer-coated Ni-rich layered cathode materials and their cathode performance
摘要： In this study, in order to develop water-resistant LiNiaCobAl1?a?bO2 (a > 0.85, NCA) cathode materials which exhibit high-rate performance, the surface coating of NCA with titanium oxide (TiOx) was examined. The synthesis conditions for the TiOx-coated NCA cathode materials were investigated, by taking into account some essential factors in the surface coating of NCA by TiOx, with a view to improving the rate performance. We successfully prepared the TiOx-coated NCA cathode material, the rate performance of which is superior to that of the conventionally prepared NCA cathode materials, typically using a polyvinylidene difluoride (PVdF) binder and N-methyl-2-pyrrolidone (NMP) solvent. Their surface analysis suggested that the specific surface structure of TiOx layer coated on the NCA particle leads to both a water-resistant property and a high permeability of Li+ ions through it in the charging/discharging process.
关键词： Lithium ion secondary battery,Water-based hybrid polymer binder,TiOx coating layer,Water resistance,Ni-rich lithium transition metal oxide
更新于2025-09-23 15:21:21
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Effect of non-metallic X(X=F, N, S) and Cr co-doping on properties of BiFeO3: A first-principles study
摘要： In this study, the structural, magnetic, electric and optical properties in X (X=F, N, S) and Cr co-doped BiFeO3 (BFO) are calculated using the density functional theory. For Cr–X co-doping case, the structure of BFO undergo a phase transition from monoclinic to triclinic structure accompanying net magnetic moments of 5.92 μB, 6.04 μB and 7.80 μB, for Cr–F co-doping, Cr–N co-doping and Cr–S co-doping, respectively. The underlying physical mechanisms are the lattice distortions tunned by doping. The decreased Fe–O–Fe bond angles and Fe–O bond lengths will bring weak antiferromagnetism superexchange interaction. In addition, the band gaps of Cr–X co-doping cases are decreased from 2.20 eV (BFO bulk) to 1.31 eV and 1.80 eV for Cr–F co-doping and Cr–S co-doping, respectively, which are well for photovoltaic applications according to the well-known Shockley-Queisser criterion, suggesting a possible great improvement optical properties in Cr–X co-doped samples.
关键词： Lattice distortion,Optical properties,Non-metal and transition-metal co-doped BiFeO3,Magnetic moments
更新于2025-09-23 15:21:01