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Length-Dependent Electronic Transport Properties of the ZnO Nanorod
摘要： The two-probe device of nanorod-coupled gold electrodes is constructed based on the triangular zinc oxide (ZnO) nanorod. The length-dependent electronic transport properties of the ZnO nanorod was studied by density functional theory (DFT) with the non-equilibrium Green’s function (NEGF). Our results show that the current of devices decreases with increasing length of the ZnO nanorod at the same bias voltage. Metal-like behavior for the short nanorod was observed under small bias voltage due to the interface state between gold and the ZnO nanorod. However, the influence of the interface on the device was negligible under the condition that the length of the ZnO nanorod increases. Moreover, the rectification behavior was observed for the longer ZnO nanorod, which was analyzed from the transmission spectra and molecular-projected self-consistent Hamiltonian (MPSH) states. Our results indicate that the ZnO nanorod would have potential applications in electronic-integrated devices.
关键词： current–voltage (I–V) curves,molecular-projected self-consistent Hamiltonian (MPSH),transport properties,zinc oxide (ZnO) nanorod,transmission spectrum
更新于2025-09-23 15:23:52
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Light-induced EPR study of spin-assisted charge transport in PFOT:PC61BM composite
摘要： Magnetic resonance, relaxation and dynamic parameters of polaron spins and methanfullerene radical anions, initiated by the infrared-visible-ultraviolet photons in bulk heterojunctions of the composite formed by narrow-band poly[(9,9-dioctylfluorenyl-2.7-diyl)-co-(bithiophene)] (PFOT, F8T2) copolymer and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) globules were investigated by the direct Light-Induced Electron Paramagnetic Resonance (LEPR) spectroscopy. It was shown that some of the polarons are captured by spin traps formed in the copolymer matrix due to its disordering. The number, spatial distribution and energy depth of such traps depend on the structure and morphology of composite. It is shown that the main parameters of both charge carriers are determined by the exchange interaction of the spin ensembles, as well as the energy of the photons. The formation of spin traps in the copolymer matrix and the exchange interaction between different spin packets cause the extreme sensitivity of the composite's magnetic resonance and electronic parameters to the number and energy of the initiating photons. The predominant photoinitiation of localized polarons in the copolymer matrix was demonstrated. This process is substantially accelerated when the composite is illuminated by photons with the energy lying near 1.8 and 2.7 eV. The recombination of both charge carriers can be described in terms of a bimolecular process of the second order. It was found that the contributions of polarons and methanofullerene radical anions to the effective paramagnetic susceptibility increase substantially near the photon energy of 2.6 and 2.1 eV due to the exchange interaction of these charge carriers. It is shown that the mobility of polarons varies monotonically throughout all the photon energy range, whereas the librational spin dynamics of the methanofullerene globules is substantially accelerated near the photon energy of 2.0 and 2.7 eV.
关键词： Polymer nanocomposites,Spin recombination,Transport properties,Spin interaction,Polaron,Light-induced EPR
更新于2025-09-23 15:23:52
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Ab-initio study of electronic, optical, thermal, and transport properties of Cr <sub/>4</sub> AlB <sub/>6</sub>
摘要： Theoretical investigation of different physical parameters of Cr4AlB6 have been done within the framework of density functional theory. Cr4AlB6 is a no band gap material. Its Cr-3d states contributes the most at the Fermi level. Thermal properties are investigated using quasi-harmonic Debye model as implemented in Gibbs code for different values of pressure and temperature. Study of transport property suggests that its electrical conductivity increases nonlinearly with increase in temperature but the relative change in its value is very low whereas its thermal conductivity increases linearly with the increase in temperature and relative increase in thermal conductivity is very high. The behavior of Cr4AlB6 is anisotropic and property is ceramic. It has potential applications in making ceramic capacitors. Its reflectivity is high in low energy region. It suggests that material can be used as coating material for far-infrared radiation. Study of the transport property suggests that because of very high value of thermal conductivity, it can be used for heat sink applications.
关键词： optical properties,first principles,electronic properties,thermal properties,thermoelectric transport properties,structural properties
更新于2025-09-23 15:22:29
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Puzzling robust 2D metallic conductivity in undoped β-Ga2O3 thin films
摘要： Here, we report the analogy of an extremely stable topological-like ultra-wide bandgap insulator, a solid that is a pure insulator in its bulk but has a metallic conductive surface, presenting a two-dimensional conductive channel at its surface that challenges our current thinking about semiconductor conductivity engineering. Nominally undoped epitaxial b-Ga2O3 thin films without any detectable defect (after a range of state-of-the-art techniques) showed the unexpectedly low resistivity of 3 × 10^-2 Ωcm which was found to be also resistant to high dose proton irradiation (2 MeV, 5 × 10^15 cm^-2 dose) and was largely invariant (metallic) over the phenomenal temperature range of 2 K up to 850 K. The unique resilience and stability of the electrical properties under thermal and highly ionizing radiation stressing, combined with the extended transparency range (thanks to the ultra-wide bandgap) and the already known toughness under high electrical field could open up new perspectives for use as expanded spectral range transparent electrodes (e.g., for UV harvesting solar cells or UV LEDs/lasers) and robust Ohmic contacts for use in extreme environments/applications and for novel optoelectronic and power device concepts.
关键词： Electron accumulation,Wide bandgap insulator,Transport properties,Ga2O3
更新于2025-09-23 15:22:29
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Preparation of thulium iron garnet ceramics and investigation of spin transport properties in thin films
摘要： Compensated ferrimagnetic thulium iron garnet ceramics were prepared by the sol-gel method, which is significantly better than conventional solid-state reactions. Saturation magnetization yielded a maximum of 16.7 emu/g for specimens sintered at 900 °C. Subsequently, using the TmIG bulk as the target, an epitaxial film was grown by pulsed laser deposition. Furthermore, the spin transport properties of film with an attached 5 nm-thick platinum layer were studied in terms of longitudinal spin Seebeck effect (LSSE) and spin Hall magnetoresistance (SMR). The LSSE coefficient was as high as 0.38 μV/K and the SMR was 0.0072%. These results indicated that the bulk material and thin film presented excellent qualities, which are extremely important for the fundamental investigation of novel spin transport behaviour in compensated ferrimagnetic insulators. These results also provide more alternatives for spintronic materials.
关键词： Magnetic insulators,Thulium iron garnet,Spin transport properties,Compensated ferrimagnet
更新于2025-09-23 15:22:29
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Effect of Terraces at the Interface on the Structural and Physical Properties of La <sub/>0.8</sub> Sr <sub/>0.2</sub> MnO <sub/>3</sub> Thin Films
摘要： Employing atomic force microscopy, transmission electron microscopy and the second harmonic generation technique, we carefully explore the structural properties of 6-unit-cell-thick La0.8Sr0.2MnO3 films grown on SrTiO3 with atomically flat TiO2-terminated terraces on the surface. The results clearly demonstrate that the terraces on the surface of TiO2-terminated SrTiO3 can improve the layer-by-layer epitaxial growth of the manganite films, which results in uniform film coverage at the beginning of growth and thus reduces the substrate-induced disorder at or near the interface. Comparing the magnetic and transport properties of La0.8Sr0.2MnO3 films with the thicknesses varying from 6 unit cells to 80 unit cells grown respectively on as-received SrTiO3 and TiO2-terminated SrTiO3, it is found that these atomically flat terraces on the surface of TiO2-terminated SrTiO3 can greatly enhance the Curie temperature and conductivities of the ultrathin La0.8Sr0.2MnO3 films with thickness less than 50 unit cells, while no obvious difference is detected in the magnetic and transport properties of the 80 unit-cell thick films.
关键词： La0.8Sr0.2MnO3,transport properties,SrTiO3,terraces,magnetic properties,structural properties
更新于2025-09-23 15:21:21
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Electronic transport in degenerate (100) scandium nitride thin films on magnesium oxide substrates
摘要： Scandium nitride (ScN) is a degenerate n-type semiconductor with very high carrier concentrations, low resistivity, and carrier mobilities comparable to those of transparent conducting oxides such as zinc oxide. Because of its small lattice mismatch to gallium nitride (GaN), <1%, ScN is considered a very promising material for future GaN based electronics. Impurities are the source of the degeneracy. Yet, which specific impurities are the cause has remained in contention. ScN thin films of various thicknesses were grown on magnesium oxide substrates in a (001) orientation using reactive magnetron sputtering across a range of deposition conditions. X-ray diffraction was used to verify crystal orientation. Film thicknesses ranging from 39 to 85 nm were measured using scanning electron microscopy. The electronic transport properties of the films were characterized using Hall-effect measurements at temperatures ranging from 10 to 320 K. At 10 K, the electron concentration varies from 4.4 (cid:2) 1020 to 1.5 (cid:2) 1021 cm(cid:3)3, resistivity from 2.1 (cid:2) 10(cid:3)4 to 5.0 (cid:2) 10(cid:3)5 X(cid:4)cm, and Hall mobility from 66 to 97 cm2/V(cid:4)s. Secondary ion mass spectroscopy (SIMS) was used to determine film compositions. Finally, density functional theory (DFT) was used to compute the activation energies for various point defects including nitrogen and scandium vacancies and oxygen and fluorine substituting for nitrogen. For both oxygen and fluorine substitution, the energies were negative, indicating spontaneous formation. Nevertheless, the combined results of the Hall, SIMS, and DFT strongly suggest that oxygen substitution is the primary mechanism behind the high carrier concentration in these samples.
关键词： degenerate n-type semiconductor,Hall-effect measurements,Scandium nitride,density functional theory,electronic transport properties
更新于2025-09-23 15:21:21
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Energy band and transport properties in magnetic aperiodic graphene superlattices of Thue-Morse sequence
摘要： Utilizing the transfer matrix method, we develop the electronic band structure and transport properties in Thue-Morse aperiodic graphene superlattices with magnetic barriers. It is found that the normal transmission is blocked and the position of the Dirac point can be shifted along the wavevector axis by changing the height and width ratio of magnetic barriers, which is intrinsic di?erent from electronic ?eld modulated superlattices. In addition, the angular threshold property of the transmission spectra and the oscillatory property of the conductance have been studied.
关键词： graphene superlattices,transport properties,electronic band structure,magnetic barriers,Thue-Morse sequence
更新于2025-09-23 15:21:01
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Alignment of Lyotropic Liquid Crystalline Conjugated Polymers in Floating Films
摘要： Directed alignment of polymer chains plays an indispensable role in charge transport properties. We focus not only on a specific method to induce the alignment but also on the design of a liquid crystalline (LC) conjugated polymer to take advantage of an intrinsic self-assembly characteristic. We synthesized a lyotropic LC conjugated polymer, CP1-P, having o-nitrobenzyl (ONB) esters as photocleavable side chains and adopted a floating film transfer method to induce the polymer chain alignment through a lyotropic LC phase transition. An optimum amount of a high boiling point solvent (1,2-dichlorobenzene) in chloroform turned out to be an important factor to maximize the polymer chain alignment. The hole transport mobility along the polymer chain alignment direction was 13?14 times higher than that in the direction perpendicular to the alignment. In addition, the removal of side chains resulted in the solvent resistivity while maintaining the alignment feature in organic thin-film transistors.
关键词： floating films,liquid crystalline conjugated polymers,photocleavable side chains,polymer chain alignment,charge transport properties
更新于2025-09-23 15:21:01
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films
摘要： We report proximity effects of spin-orbit coupling in EuO1?x ?lms capped with a Pt overlayer. Transport measurements suggest that current ?ows along a conducting channel at the interface between the Pt and EuO. The temperature dependence of the resistivity picks up the critical behaviors of EuO, i.e., the metal-to-insulator transition. We also ?nd an unusual enhancement of the magnetic anisotropy in this structure from its bulk value, which results from strong spin-orbit coupling across the Pt/EuO1?x interface.
关键词： magnetic anisotropy,Pt/EuO interface,spin-orbit coupling,transport properties
更新于2025-09-23 15:21:01