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Analysis of Cu doping concentration on PbS thin films for the fabrication of solar cell using feasible nebulizer spray pyrolysis
摘要： This report portrays the analysis of Cu doping concentration (%) on PbS thin films prepared by feasible nebulizer spray technique. The doping percentage of Cu was increased from 0% to 8% in steps of 2%. X-ray diffraction study of the films evinces the nature of the films as polycrystalline with simple cubic crystal structure. The calculated crystallite size was varied from 55 to 41 nm on increasing the Cu doping concentration. SEM/AFM studies proclaim that the cubic shaped grains have covered the entire film surface. The shape of grains was amended with respect to the increase in Cu doping concentration. An elevation in band gap from 1.61 eV to 2.10 eV was spotted for the raise in Cu doping concentration from 0% to 6%. The near band edge emission peak at 575 nm was sensed from PL spectra in which the intensity was enhanced. Hall Effect measurement declared the p-type conductivity nature for the prepared PbS films. Resistivity and carrier-concentration values are 0.73×103 Ωcm and 6.04×1013 cm-3 respectively for 6% Cu doped PbS thin films. Efficiency for the solar cell FTO/n-CdS/p-Cu:PbS structure constructed with 6% Cu doped PbS film is about 0.68%.
关键词： X-ray diffraction,PL spectra,Hall Effect measurement,AFM/SEM,Cu doped PbS film
更新于2025-11-21 11:18:25
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Fabrication and characterization of lead sulfide (PbS) thin film based heterostructure (FTO/CdS/PbS/Ag) solar cell by nebulizer spray method
摘要： This work deals with the study on the key properties of PbS thin films prepared by simple nebulizer spray method. The structural study done by XRD exhibited cubic crystal structure with polycrystalline nature for the deposited PbS films. The obtained crystallite size was varied between 41 to 55 nm for various molar concentrations. The morphology study done by SEM displays uniform distribution of the grains all over the surface of the prepared PbS thin films. The observed band gap value was decreased from 1.8 eV to 1.51 eV for various molar concentrations. The emitted PL intensity was strong at about 580 nm which is related to the near band edge (NBE) emission. Electrical studies performed by Hall Effect measurement confirm the p-type conductivity of prepared films. Resistivity and carrier concentrations are 2.92×103 Ω-cm and 4.83×1013cm-3 respectively for the deposited films. In addition, a heterojunction solar cell of structure FTO/n-CdS/p-PbS/Ag was produced and its conversion efficiency was ~ 0.39%.
关键词： SEM,PbS,Heterojunction device.,Hall Effect,Photoluminescence
更新于2025-11-21 11:18:25
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Synthesis, Morphology, Optical and Electrical Properties of Cu <sub/> 1? <i>x</i> </sub> Fe <sub/><i>x</i> </sub> O Nanopowder
摘要： The pure and Fe-doped CuO nanoparticles of the series Cu1?xFexO (x = 0, 0.027, 0.055, 0.097 and 0.125) were synthesized by a simple low temperature sol–gel method. Synthesized samples were characterized by a series of techniques including Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray electron spectroscopy (EDX), Diffuse Reflectance Spectroscopy (DRS), Fourier Transform Infrared Spectroscopy (FTIR), Hall Effect Set-up and Current–Voltage (I–V) characteristics. FESEM analysis shows formation of disc type structure increasing in grain size with Fe concentration in CuO. EDX confirmed the incorporation of iron in CuO. FTIR results of pure and Fe doped CuO samples have confirmed the formation of monoclinic CuO. The optical band gap estimated using Diffuse Reflectance Spectroscopy (DRS) shows the increment in the band gap values with Fe substitution. The Hall measurements show predominantly p-type conduction in all the samples and carrier densities decrease with increased Fe substitution. I–V characteristics of pure and Fe doped CuO nanoparticles show rectification behaviour of Schottky diodes.
关键词： Defect States,Hall Effect,Schottky Diode,Cation Vacancies,Fe-Substituted CuO
更新于2025-11-19 16:56:35
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Diluted Oxide Interfaces with Tunable Ground States
摘要： The metallic interface between two oxide insulators, such as LaAlO3/SrTiO3 (LAO/STO), provides new opportunities for electronics and spintronics. However, due to the presence of multiple orbital populations, tailoring the interfacial properties such as the ground state and metal-insulator transitions remains challenging. Here, an unforeseen tunability of the phase diagram of LAO/STO is reported by alloying LAO with a ferromagnetic LaMnO3 insulator without forming lattice disorder and at the same time without changing the polarity of the system. By increasing the Mn-doping level, x, of LaAl1?xMnxO3/STO (0 ≤ x ≤ 1), the interface undergoes a Lifshitz transition at x = 0.225 across a critical carrier density of nc = 2.8 × 1013 cm?2, where a peak TSC ≈255 mK of superconducting transition temperature is observed. Moreover, the LaAl1?xMnxO3 turns ferromagnetic at x ≥ 0.25. Remarkably, at x = 0.3, where the metallic interface is populated by only dxy electrons and just before it becomes insulating, a same device with both signatures of superconductivity and clear anomalous Hall effect (7.6 × 1012 cm?2 < ns ≤ 1.1 × 1013 cm?2) is achieved reproducibly. This provides a unique and effective way to tailor oxide interfaces for designing on-demand electronic and spintronic devices.
关键词： anomalous Hall effect,2D electron liquid,oxide interfaces,superconductivity,metal-insulator transitions
更新于2025-09-23 15:23:52
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Nuclear spin dynamics in [001] AlAs quantum well in the regime of integer and fractional quantum Hall effect
摘要： Relaxation of nuclear spins located in the vicinity of 2D electron system confined in a 16 nm [001] AlAs/AlGaAs quantum well was studied with the aid of electron spin resonance (ESR) in the regime of integer and fractional quantum Hall effect. Nuclear spin-lattice relaxation time τ was measured from the time decay of the Overhauser shift near different filling factors of the electron system. The resultant dependence of τ on filling factor turned out to be nontrivial. At the temperature 1.5 K τ reached its maximal value at the exact filling ν = 1 and decreased when ν was altered, yet this maximum vanished when the system was cooled down to 0.5 K. The fractional quantum Hall effect state at the filling of 2/3 was formed at the temperature of 0.5 K, and the development of this state was accompanied by the slowing of the nuclear spin relaxation. This observation suggests the enhancement of energy gap in the spin excitation spectrum of two-dimensional electrons at 2/3 state.
关键词： quantum wells,quantum Hall effect,spin dynamics,electron paramagnetic resonance
更新于2025-09-23 15:23:52
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Electromagnetic and gravitational responses of photonic Landau levels
摘要： Topology has recently become a focus in condensed matter physics, arising in the context of the quantum Hall effect and topological insulators. In both of these cases, the topology of the system is defined through bulk properties (‘topological invariants’) but detected through surface properties. Here we measure three topological invariants of a quantum Hall material—photonic Landau levels in curved space—through local electromagnetic and gravitational responses of the bulk material. Viewing the material as a many-port circulator, the Chern number (a topological invariant) manifests as spatial winding of the phase of the circulator. The accumulation of particles near points of high spatial curvature and the moment of inertia of the resultant particle density distribution quantify two additional topological invariants—the mean orbital spin and the chiral central charge. We find that these invariants converge to their global values when probed over increasing length scales (several magnetic lengths), consistent with the intuition that the bulk and edges of a system are distinguishable only for sufficiently large samples (larger than roughly one magnetic length). Our experiments are enabled by applying quantum optics tools to synthetic topological matter (here twisted optical resonators). Combined with advances in Rydberg-mediated photon collisions, our work will enable precision characterization of topological matter in photon fluids.
关键词： photonic Landau levels,quantum Hall effect,chiral central charge,Chern number,mean orbital spin,topological invariants
更新于2025-09-23 15:23:52
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An adapted method for analyzing 4H silicon carbide metal-oxide-semiconductor field-effect transistors
摘要： Silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs) are key devices for next-generation power electronics. However, accurate determination of device parameters from 3-terminal characteristics is hampered by the presence of interface traps. Here we present a method that, in contrast to previous evaluation schemes, explicitly considers those defects. A well-tractable parametrization of the SiC/SiO2-specific interface trap spectrum is introduced that reflects the body of known data. With this ingredient, we develop an analysis that targets for an accurate determination of device parameters from simple 3-terminal characteristics. For its validation, we investigate MOSFETs with significantly different defect densities. The resulting parameters – charge carrier density, mobility and threshold voltage – are in excellent agreement with Hall effect investigations on the very same devices, avoiding systematic errors inherent to conventional evaluation techniques. With this adapted scheme, 4H-SiC power MOSFETs, even packaged, can be meaningfully characterized, speeding up innovation cycles in energy-saving power electronics.
关键词： mobility,Silicon carbide,Hall effect,interface traps,threshold voltage,MOSFET
更新于2025-09-23 15:23:52
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Sharp increase in the density of states in PbTe upon approaching a saddle point in the band structure
摘要： PbTe is a leading mid-range thermoelectric material with a zT that has been enhanced by, amongst other methods, band engineering. Here we present an experimental study of the Hall effect, quantum oscillations, specific heat, and electron microprobe analysis that explores the evolution of the electronic structure of PbTe heavily doped with the 'ideal' acceptor Na up to the solubility limit. We identify two phenomenological changes that onset as the electronic structure deviates from a Kane-type dispersion at around 180 meV; a qualitative change in the field dependence of the Hall effect indicative of an increase in the high-field limit and a change in the Fermiology, and a sharp increase in the density of states as a function of energy. Following consideration of three possible origins for the observed phenomenology we conclude that the most likely source is nonellipsoidicity of the L pocket upon approach to a saddle point in the band structure, which is evidenced directly by our quantum oscillation measurements. Comparison to density functional theory calculations imply that this evolution of the electronic structure may be a key contributor to the large thermopower in PbTe.
关键词： band structure,PbTe,Hall effect,density of states,thermoelectric,quantum oscillations
更新于2025-09-23 15:23:52
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High-frequency breakdown of the integer quantum Hall effect in GaAs/AlGaAs heterojunctions
摘要： The integer quantum Hall effect is a well-studied phenomenon at frequencies below about 100 Hz. The plateaus in high-frequency Hall conductivity were experimentally proven to retain up to 33 GHz, but the behavior at higher frequencies has remained largely unexplored. Using continuous-wave terahertz spectroscopy, the complex Hall conductivity of GaAs/AlGaAs heterojunctions was studied in the range of 69–1100 GHz. Above 100 GHz, the quantum plateaus are strongly smeared out and replaced by weak quantum oscillations in the real part of the conductivity. The amplitude of the oscillations decreases with increasing frequency. Near 1 THz, the Hall conductivity does not reveal any features related to the filling of Landau levels. Similar oscillations are observed in the imaginary part as well; this effect has no analogy at zero frequency. This experimental picture is in disagreement with existing theoretical considerations of the high-frequency quantum Hall effect.
关键词： integer quantum Hall effect,GaAs/AlGaAs heterojunctions,terahertz spectroscopy,high-frequency Hall conductivity,quantum oscillations
更新于2025-09-23 15:22:29
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Room temperature spin Hall effect in graphene/MoS <sub/>2</sub> van der Waals heterostructures
摘要： Graphene is an excellent material for long distance spin transport but allows little spin manipulation. Transition metal dichalcogenides imprint their strong spin-orbit coupling into graphene via proximity effect, and it has been predicted that efficient spin-to-charge conversion due to spin Hall and Rashba-Edelstein effects could be achieved. Here, by combining Hall probes with ferromagnetic electrodes, we unambiguously demonstrate experimentally spin Hall effect in graphene induced by MoS2 proximity and for varying temperature up to room temperature. The fact that spin transport and spin Hall effect occur in different parts of the same material gives rise to a hitherto unreported efficiency for the spin-to-charge voltage output. Remarkably for a single graphene/MoS2 heterostructure-based device, we evidence a superimposed spin-to-charge current conversion that can be indistinguishably associated with either the proximity-induced Rashba-Edelstein effect in graphene or the spin Hall effect in MoS2. By comparing our results to theoretical calculations, the latter scenario is found the most plausible one. Our findings pave the way towards the combination of spin information transport and spin-to-charge conversion in two-dimensional materials, opening exciting opportunities in a variety of future spintronic applications.
关键词： Spin Hall effect,Spin-orbit proximity,Rashba-Edelstein effect,Graphene,Transition metal dichalcogenides
更新于2025-09-23 15:22:29