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Topics in Present-day Science Technology and Innovation: Ultrafast Relaxation Processes in Semiconductors
摘要： The nowadays notable development of all the modern technology, fundamental for the progress and well being of world society, imposes a great deal of stress in the realm of basic Physics, more precisely on Thermo-Mechanical Statistics. In electronics and optoelectronics we face situations involving physical-chemical systems far-removed-from equilibrium, where ultrafast (in pico- and femto-second scale) and non-linear processes are present. Here we describe in an extended overview the question of ultrafast relaxation processes in the excited plasma in semiconductors.
关键词： nonequilibrium thermodynamic,ultrafast relaxation,semiconductors
更新于2025-09-19 17:15:36
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Synthesis of SnSb2Te4 Microplatelets by High-energy Ball Milling
摘要： In this work we demonstrate that high-energy ball milling process can be used to synthesize SnSb2Te4 without surfactant and further annealing. Milling parameters such as ball to raw material ratio (5:1) and milling time (2h) were determined to be suitable for synthesizing microplatelets of SnSb2Te4. The powders after milling for various durations were characterized by X-ray powder diffraction, scanning electron microscopy and electrical resistance measurements.
关键词： mechanical alloying,semiconductors,electrical properties
更新于2025-09-19 17:15:36
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Synthesis and structural characterization of microcrystalline Ga2S3 layers on a GaP semiconductor substrate
摘要： Gallium sulfide (Ga2S3) belongs to a group of wide bandgap semiconductors with interesting properties for infrared and nonlinear optics applications. Recent interest in Ga2S3 material focuses on the passivation of various semiconductor surfaces to enhance their electrical and optical properties. This work concerns the growth of microcrystalline gallium sulfide layers on semiconductive GaP substrates. The Ga2S3 layers were successfully obtained by reacting sulfur vapour with thin GaP semiconductor plates at two different temperatures: 450 °C and 600 °C. At the lower temperature (400 °C), no gallium sulfide layer formation was observed on the GaP substrate. Atomic force microscopy and Scanning Electron Microscopy were applied to illustrate the topography of the obtained Ga2S3 layers. Their thickness ranged from a few hundred nanometers to about 1–2 μm. The synthesized layers were structurally characterized by Raman spectroscopy. Raman polarization measurements were used to determine the crystalline phase of the Ga2S3 films. Raman tensor coefficients were obtained by fitting the most intensive Ga2S3 peaks to experimental data. The symmetry of the Raman peaks was in good agreement with the monoclinic Ga2S3 crystal phase.
关键词： Ga2S3 layers,Raman polarization measurements,Gallium (III) sulfide,Wide bandgap semiconductors
更新于2025-09-19 17:15:36
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Influences of Mn doping on the microstructural, semiconducting and optoelectronic properties of HgO nanostructure films
摘要： Mn-doped HgO nanostructured thin films (Hg1-xMnxO) have been prepared using electron beam evaporation technique on Corning glass (1022) substrate at room temperature with different concentrations x = 0, 0.015, 0.05, 0.1, 0.15 and 0.2. The microstructural, morphological, semiconducting and optoelectronic properties of the films have been investigated. The X-ray diffraction spectra suggest a hexagonal wurtzite type structure with lattice parameters decreased with increasing Mn content. It was found that the average particle size of the films decreases with increasing Mn doping which is confirmed by FE-SEM and AFM micrographs. The optical band gap of the investigated Mn-doped HgO nanocrystalline films is determined from the absorption coefficient and found to increase with the increase of Mn concentration which is attributed to the sp-d exchange interaction and/or the quantum confinement effect. The refractive index and extinction coefficient of the Mn-doped HgO films are also reported. The refractive index dispersion n(λ) is analyzed by single-effective-oscillator dispersion model proposed by the Wemple–DiDomenico (WDD). The oscillator parameters were estimated. The obtained dispersion values are suitable for the design of optoelectronic devices.
关键词： microstructure properties,Nanomaterial,Diluted magnetic semiconductors,single oscillator parameters,optical properties
更新于2025-09-19 17:15:36
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Synthesis of cocoon-like Ag3PO4 and its high-performance in photocatalytic degradation of ciprofloxacin
摘要： Cocoon-like Ag3PO4 (C-Ag3PO4) with hollow structure was synthesized via ion-exchange route using Ag2MoO4 and Na2HPO4 as precursors. Photocatalytic degradation experiments of the C-Ag3PO4 toward ciprofloxacin (CIP) were investigated under visible light irradiation. The C-Ag3PO4 showed superior photodegradation of CIP owing to its larger surface area and hollow structure. Besides, the C-Ag3PO4 exhibited improved photocatalytic performance and good stability after repeating cycles, which could be attributed to the formed metal silver under visible light irradiation. Moreover, radical trap experiment was carried out, which indicated that the photo-induced holes (h+) and superoxide radicals (?O2?) acted as the main reactive species in the photodegradation process.
关键词： Ciprofloxacin,Hollow structure,Semiconductors,Ag3PO4,Photocatalysis
更新于2025-09-19 17:15:36
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Modeling the AC Electrokinetic Behavior of Semiconducting Spheres
摘要： We study theoretically the dielectrophoresis and electrorotation of a semiconducting microsphere immersed in an aqueous electrolyte. To this end, the particle polarizability is calculated from first principles for arbitrary thickness of the Debye layers in liquid and semiconductor. We show that the polarizability dispersion arises from the combination of two relaxation interfacial phenomena: charging of the electrical double layer and the Maxwell–Wagner relaxation. We also calculate the particle polarizability in the limit of thin electrical double layers, which greatly simplifies the analytical calculations. Finally, we show the model predictions for two relevant materials (ZnO and doped silicon) and discuss the limits of validity of the thin double layer approximation.
关键词： microspheres,dielectrophoresis,electrorotation,semiconductors,electrokinetics
更新于2025-09-19 17:15:36
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Structural and Optical Properties of Ga2Se3 Crystals by Spectroscopic Ellipsometry
摘要： Optical and crystalline structure properties of Ga2Se3 crystals were analyzed utilizing ellipsometry and x-ray diffraction (XRD) experiments, respectively. Components of the complex dielectric function (e = e1 + ie2) and refractive index (N = n + ik) of Ga2Se3 crystals were spectrally plotted from ellipsometric measurements conducted from 1.2 eV to 6.2 eV at 300 K. From the analyses of second-energy derivatives of e1 and e2, interband transition energies (critical points) were determined. Absorption coefficient–photon energy dependency allowed us to achieve a band gap energy of 2.02 eV. Wemple and DiDomenico single effective oscillator and Spitzer–Fan models were accomplished and various optical parameters of the crystal were reported in the present work.
关键词： critical points,optical properties,optical constants,Semiconductors
更新于2025-09-19 17:15:36
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Ge <sub/>x</sub> Si <sub/>1-x</sub> Virtual-Layer Enhanced Ferromagnetism in Self-assembled Mn <sub/>0.06</sub> Ge <sub/>0.94</sub> Quantum Dots Grown on Si Wafers by Molecular Beam Epitaxy
摘要： The self-assembled Mn0.06Ge0.94 quantum dots (QDs) on Si substrate or GexSi1-x virtual substrate (VS) were grown by molecular beam epitaxy. The GexSi1-x VS of different thicknesses and Ge compositions x were utilized to modulate the ferromagnetic properties of the above QDs. The MnGe QDs on GexSi1-x VS show a significant enhanced-ferromagnetism with a Curie temperature above 220 K. On the basis of the microstructural and magnetization results, the ferromagnetic properties of the QDs on GexSi1-x VS are believed to come from the intrinsic MnGe ferromagnetic phase rather than any intermetallic ferromagnetic compounds of Mn and Ge. At the same time, we found that by increasing Ge composition x of GexSi1-x VS, the ferromagnetism of QDs grown on VS will markedly increase due to the improvements of hole concentration and Ge composition inside the QDs. These results are fundamentally important in the understanding and especially to the realization of high Curie temperature MnGe diluted magnetic semiconductors.
关键词： ferromagnetism,molecular beam epitaxy,diluted magnetic semiconductors,GexSi1-x virtual substrate,MnGe quantum dots
更新于2025-09-19 17:13:59
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Effective design of novel low band gap acceptors for non-fullerene solar cells via modulating molecular planarity and F atom substitution
摘要： Due to the highly tunable molecular energy levels and potential for reducing synthesis costs, increased efforts have been devoted to developing non-fullerene acceptors. Herein we report two novel low band gap NF-SMAs for OSCs, namely IDBTC and IDBTCF. Thiophene-substituted benzothiadiazole is introduced between the donor and acceptor to regulate the coplanarity of the molecule and enhance intramolecular push-pull effect. In addition, the ?uorine atom was introduced into the benzothiadiazole to study the effect of ?uorination on the properties of NF-SMAs. As expected, they all exhibited good near infrared absorption and narrow band gap (Eopt < 1.6 ev). What’s more, the absorption spectrum is slightly enhanced and the energy level is shifted, by the introduction of ?uorine atoms into NF-SMAs. Furthermore, NF-SMAs were treated as acceptor and P3HT as donor in OSCs. The best device based on IDBTCF delivered a PCE of 3.22%. The PCE has increased from 2.5% (IDBTC) to 3.22% (IDBTCF) after introduction of ?uorine atoms. It indicates that the optical properties and electronic energy levels of NF-SMAs can be readily tuned by modulation of molecular planarity and the introduction of ?uorine atoms, which provides great opportunities for enhance the ef?ciency of OSCs.
关键词： Solar energy material,Organic,Semiconductors
更新于2025-09-19 17:13:59
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Low-Cost RoHS Compliant Solution Processed Photovoltaics enabled by Ambient Condition Synthesis of AgBiS2 Nanocrystals
摘要： Two major challenges exist before colloidal nanocrystal solar cells can take their place in the market: So far these devices are based on Pb/Cd containing nanocrystals and secondly the synthesis of these nanocrystals takes place in inert atmosphere at elevated temperatures due to the use of air-sensitive chemicals. In this report, a room-temperature, ambient-air synthesis for non-toxic AgBiS2 nanocrystals is presented. As this method utilizes stable precursors, the need for the use of a protective environment is eliminated, enabling the large-scale production of AgBiS2 nanocrystals. The production cost of AgBiS2 NCs at room temperature and under ambient conditions reduces by ~ 60 % compared to prior reports based on hot injection and the solar cells made of these nanocrystals yield a promising power conversion efficiency (PCE) of 5.5 %, the highest reported to date for a colloidal nanocrystal material free of Pb or Cd synthesized at room temperature and under ambient conditions.
关键词： semiconductors,room temperature,non-toxic,solar cells,nanocrystals
更新于2025-09-19 17:13:59