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Correlation between magneto-optical and transport properties of Sr doped manganite films
摘要： The features of electronic structure of La0.7Sr0.3MnO3, Pr0.8Sr0.2MnO3, and Pr0.6Sr0.4MnO3 polycrystalline films of different thickness have been investigated using magnetic circular dichroism (MCD) in the range of 1.1e4.2 eV. The temperature behavior of the samples electrical resistance were also has been studied. It was found that films with high Sr content (0.3 and 0.4) act as high-temperature semiconductors, while the maximum in the temperature dependences of resistivity these films indicates the transition of the samples to the metallic state at some temperature TM-S, which is different for different sample thickness. The films with the lower Sr content (0.2) act as insulators in the used temperature range. The MCD spectra have been decomposed to the Gaussian-shaped lines, and the temperature dependence of intensity of each line has been analyzed in comparison with temperature dependence of the films magnetization and with their electric conductivity type. Different temperature behavior of the intensity of four specified Gaussian-lines was revealed for semiconductor films. In the case of insulating Pr0.8Sr0.2MnO3 samples, the intensity of three specified Gaussian lines changes with the temperature in the same way as the magnetization changed. It was established that the lanthanide (La, Pr) type does not affect the MCD spectra shape for the films with the same electrical conductivity type. Besides, the correlation between the MCD data of the films and their conductivity type was revealed. Due to the detailed analysis of the specified Gaussian lines with taking into account the well-known in the literature absorption bands, lying outside the studied spectral region, the MCD bands for the studied manganite films have been identified with electronic transitions of a different nature.
关键词： Magnetic circular dichroism,Thin films,Electronic properties,Electrical transport,Crystal structure,Manganites
更新于2025-09-23 15:23:52
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Schottky Contacts on Polarity-Controlled Vertical ZnO Nanorods
摘要： Polarity-controlled growth of ZnO by chemical bath deposition provides a method for controlling the crystal orientation of vertical arrays of nanorods. The ability to define the morphology and structure of the nanorods is essential to maximising the performance of optical and electrical devices such as piezoelectric nanogenerators; however, well-defined Schottky contacts to the polar facets of the structures have yet to be explored. In this work, we demonstrate a process to fabricate metal-semiconductor-metal device structures from vertical arrays with Au contacts on the uppermost polar facets of the nanorods and show the O-polar nanorods (~0.44 eV) have a greater effective barrier height than the Zn-polar nanorods (~0.37 eV). Oxygen plasma treatment is shown by Cathodoluminescence (CL) spectroscopy to reduce mid-gap defects associated with radiative emissions that improves the Schottky contacts from weakly-rectifying to strongly-rectifying. Interestingly, the plasma treatment was shown to have a much greater effect in reducing the number of carriers in O-polar nanorods through quenching of the donor-type substitutional hydrogen on oxygen sites (HO) when compared to the zinc vacancy related hydrogen defect complexes (VZn, Hn) in Zn-polar nanorods that evolve to lower coordinated complexes. The effect on HO in the O-polar nanorods coincided with a large reduction in the visible range defects producing a lower conductivity and creating the larger effective barrier heights. This combination can allow radiative losses and charge leakage to be controlled enhancing devices such as dynamic photodetectors, strain sensors, and LEDs while showing the O-polar nanorods can outperform Zn-polar nanorods in such applications.
关键词： ZnO,Cathodoluminescence,Electrical Transport,Polarity,Schottky Contacts,Nanorods,Defects
更新于2025-09-23 15:21:01
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Tl2S-GeS GeS2 system: Glass formation, macroscopic properties, and charge transport
摘要： the previously obtained conductivity and A relevant approach was found to study the glass-forming region, macroscopic properties and electrical conductivity changes in the Tl2S-GeS-GeS2 system by analysing two composition glass lines (Tl2S)x(GeS2)100-x (0 ≤ x ≤ 50) and (Tl2S)10(GeS)x(GeS2)90-x (0 ≤ x ≤ 90) together with three thallium containing crystalline compounds Tl4Ge4S10, Tl4Ge2S6 and Tl4GeS4. The crystallization ability variation in the binary Tl2S-GeS2 system can be explained comparing the structural characteristics of glasses and closest crystalline compounds. The room temperature dc conductivity increases by 7 orders of magnitude with increasing thallium concentration and reaches the value of 10-8 S cm-1 for (Tl2S)50(GeS2)50 sample. Combined with thallium diffusion parameters for (Tl2S)x(GeS)60(GeS2)40-x and (Tl2S)x(GeS)50-x/2(GeS2)50-x/2 composition lines as well as with conductivity characteristics for the crystalline analogues, ionic and electronic conductivities in the (Tl2S)x(GeS2)100-x glasses were estimated separately. The Tl-poor glasses (x ≤ 0.25) are essentially semiconductors, while the Tl-rich vitreous alloys appear to be ionic conductors. The conductivity parameters for (Tl2S)10(GeS)x(GeS2)90-x glasses change non- monotonically with GeS concentration passing by the conductivity minimum for 60% mol. GeS. The same behaviour was observed for thallium free (GeS)x(GeS2)100-x matrix, showing the influence of the GeS/GeS2 ratio on the properties of the thallium-poor semiconducting glasses.
关键词： glass formation,electrical transport,ionic conduction,Thallium thiogermanate glasses
更新于2025-09-23 15:21:01
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A Predictive Model for the Electrical Transport Within Nanowire Networks
摘要： Thin networks of high aspect ratio conductive nanowires can combine high electrical conductivity with excellent optical transparency, which has led to a widespread use of nanowires in transparent electrodes, transistors, sensors, and ?exible and stretchable conductors. Although the material and application aspects of conductive nanowire ?lms have been thoroughly explored, there is still no model which can relate fundamental physical quantities, like wire resistance, contact resistance and nanowire density, to the sheet resistance of the ?lm. Here we derive an analytical model for the electrical conduction within nanowire networks based on an analysis of the parallel resistor network. The model captures the transport characteristics and ?ts a wide range of experimental data, allowing for the determination of physical parameters and performance limiting factors, in sharp contrast to the commonly employed percolation theory. The model thus constitutes a useful tool with predictive power for the evaluation and optimization of nanowire networks in various applications.
关键词： nanowires,electrical transport,model,percolation,carbon nanotubes,nanowire network,silver nanowires
更新于2025-09-23 15:21:01
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Electrical transport properties and complex impedance investigation of Fe3+ and La3+ co-doping (Pb,Sr)TiO3 thin films
摘要： This work investigates the impact of Fe3+ and La3+ co-doping on the structural, electrical transport and dielectric relaxation properties of PST thin films. XRD and Raman spectroscopy data show that the Fe3+ and La3+ doping induce a pseudocubic to tetragonal structural phase transformation. Schottky barrier heights calculated from temperature-dependent current–voltage plots for the PST, PSTF and PSLTF films decreased to 1.20, 0.59, and 0.36 eV, respectively. This behavior was directly assigned to the increase in oxygen vacancies. The frequency dependence of sample’s impedance revealed the presence of the typical electrical relaxation phenomenon in all films. Activation energies calculated from the imaginary part of the impedance are 1.73 and 0.57 eV: the high value (1.73 eV, PST films) suggests the presence of long-range oxygen vacancy diffusion, while the lower one (0.57 eV PSLTF films) should be associated to the short-range oxygen vacancy diffusion.
关键词： Dielectric relaxation,Thin films,Electrical transport,Impedance spectroscopy
更新于2025-09-23 15:21:01
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A Synergy of Strain Loading and Laser Radiation in Determining the High-Performing Electrical Transports in the Single Cu-Doped SnSe Microbelt
摘要： Semiconducting microbelts are key components of the thermoelectric micro-devices, and their electrical transport properties play significant roles in determining the thermoelectric performance. Here, we report heavily Cu-doped single-crystal SnSe microbelts as potential candidates employed in thermoelectric micro-devices, fabricated by a facile solvothermal route. The considerable Cu-doping concentration of ~11.8 % up to the solubility contributes to a high electrical conductivity of ~416.6 S m-1 at room temperature, improved by one order of magnitude compared with pure SnSe (38.0 S m-1). Meanwhile, after loading ~1 % compressive strain and laser radiation, the electrical conductivity can be further improved to ~601.9 S m-1 and ~589.2 S m-1, respectively, indicating great potentials for applying to thermoelectric micro-devices. Comprehensive structural and compositional characterizations indicate that the Cu+ doping state provides more hole carriers into the system, contributing to the outstanding electrical conductivity. Calculations based on first-principle density functional theory reveal that the heavily doped Cu lowers the Fermi level down into the valence bands, generating holes, and the 1 % strain can further reduce the bandgap, strengthening the ability to release holes, and, in turn, leading to such an excellent electrical transport performance. This study fills the gaps of finding novel materials as potential candidates employed in the thermoelectric micro-devices and provides new ideas for micro/nanoscale thermoelectric material design.
关键词： Cu-doping,tin selenide,electrical transport performance,laser radiation,strain loading
更新于2025-09-23 15:19:57
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Controlled optoelectronic properties and abrupt change in photosensitivity by suppressing density of oxygen vacancies in SnO <sub/>2</sub> nanocrystalline thin films prepared at various spray-deposition temperatures
摘要： Nanostructured SnO2 thin films were synthesized at various substrate temperatures using a modified chemical spray pyrolysis (MCSP) technique. The x-ray diffraction (XRD) patterns confirmed the presence of a rutile SnO2 with tetragonal structure for all the resultant film samples. The XRD results ascertained increase in the grain growth rate and consequent enhancement in crystallinity with increasing the spray-deposition temperature. The optical spectroscopic analysis revealed a significant increase in the optical transmission within the visible region as well as a considerable increase in the optical bandgap by increasing the deposition temperature. However, the spectral distribution of the absorption coefficient ascertained the dominance of direct allowed transition for the SnO2 film samples. The analysis of the current-voltage characteristic curves revealed that the variation of the spray-deposition temperature strongly influences the photosensitivity of the film samples. Based on the electrical results, these film samples reveal a semiconductor behaviour of the transport property over the entire investigated range of the working temperature, with two different conduction mechanisms. The optical and electrical results were combined to evaluate the influence of varying the deposition temperature on the figure of merit (FOM) factor for the SnO2 film samples.
关键词： MCSP technique,optical spectroscopic analysis,electrical transport properties,figure of merit,structural properties,spray deposition temperature
更新于2025-09-23 15:19:57
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Structural and electrical properties of Sb<sub>x</sub>W<sub>1-x</sub>Se<sub>2</sub> (0, 0.5) ternary alloys
摘要： In present article, we demonstrated for the first time the synthesis and properties of SbXW1-XSe2 (0, 0.5) ternary alloys. The crystals of SbXW1-XSe2 (0, 0.5) ternary alloys were grown by direct vapour transport technique. The XRD results confirm the 2H-hexagonal lattice structure with P63/mmc space group and grown crystals are highly crystallographic c-axis oriented. The screw dislocation mechanism is predominating in the growth process of Sb0.5W0.5Se2 crystals. The results of electrical characterization show n-type semiconducting nature. The Raman spectra exhibit peaks corresponding to out of plane A1g, in-plane E2g and 2LA modes of vibration which is attributing the 2H-polymorph of grown SbXW1-XSe2 (0, 0.5) ternary alloys. The results shows substitution of Sb (+5) on W (+4) lattice site due to similar ionic size. The band gap tailoring from 0.93 to 1.40 eV is achieved, suggesting the effective way to tune the material characteristics for high performance devices.
关键词： structural properties,SbXW1-XSe2 (0,Growth of single crystal,0.5) ternary alloys,electrical transport
更新于2025-09-19 17:15:36
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Universal Hall Coefficient Correction in Strongly Coupled Cr‐SiO <sub/>2</sub> Nanogranular Metals
摘要： The microstructure and electrical transport properties of Crx(SiO2)1?x nanogranular films with Cr volume faction x ≈ 0.67 and 0.72 are systematically investigated. The transmission electron microscopy images and elemental mappings indicate that the films are quite inhomogeneous: some Cr granules directly connect to others while some Cr granules with size ≈1–3 nm disperse in the SiO2 dielectric matrix. For each film, the Hall coefficient RH varies linearly with the natural logarithm of temperature, i.e., ΔRH ∝ lnT, above ≈60 K, saturates at ≈60 K, and retains the saturating value below ≈60 K. The temperature dependence of Hall coefficient can be explained by the recent theory in granular metals and originates from virtual diffusion of electrons through the metallic granules. For the conductivity σ, a robust Δσ ∝ √T is observed from ≈50 down to 2 K. The behavior of the conductivity stems from the “Altshuler–Aronov” correction, whose influence on the Hall coefficient is not present in the films.
关键词： Hall transport,electrical transport,quantum effects of Coulomb interaction,granular films
更新于2025-09-19 17:13:59
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Defects controlled doping and electrical transport in TiS <sub/>2</sub> single crystals
摘要： TiS2 has been intensively studied as an electrode material and a thermoelectric material for energy storage and conversion applications due to its high electrical conductivity. Understanding the influence of defects on electrical transport is of importance not only to resolve the long-standing question concerning the nature of TiS2, but also for the rational design of TiS2 based devices for energy scavenging applications. In this study, we integrate photoemission spectroscopy, Raman spectroscopy, and electrical transport measurements to determine the chemical compositions dominated by defects and their influence on the doping and electrical properties. Our results demonstrate that TiS2 is a heavily self-doped semiconductor with the Fermi level close to the conduction band, which serves as the conclusive experimental evidence regarding the semiconducting nature of TiS2. The doping effect is sensitive to the (subtle) changes in the chemical composition. The electron donation from the Ti interstitials (Tii) to the TiS2 host explains the high carrier concentration. The Ti Frenkel pair (TiF) acting as the acceptor is responsible for the decrease in the electron carrier concentration and electrical conductivity. High conductivity maintains upon partial oxidization, indicating the oxidization-tolerance in terms of the electronic structure. Our results provide valuable insight into the evolution of electronic properties modulated by defects that reveal unambiguously the self-doped semiconducting nature of TiS2 and chemical- and environment-tolerance of TiS2 as an advanced energy scavenging material.
关键词： TiS2,doping,defects,electrical transport,energy storage,energy conversion,photoemission spectroscopy,thermoelectric material,Raman spectroscopy
更新于2025-09-19 17:13:59