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Cu(In,Ga)Se2 monograin powders with different Ga content for solar cells
摘要： Monograin layer (MGL) solar cell technology based on CuIn1-xGaxSe2 (CIGSe) monograin powder crystals is a promising approach for the future low-cost production of flexible solar panels. In this study, CuIn1-xGaxSe2 monograin powders (0 ≤ x ≤ 1) were prepared from binary compounds in the liquid phase of potassium iodide as flux material in evacuated quartz ampoules at 720 °C. The crystal structure and the lattice parameters of the CIGSe monograin powder crystals were determined by using X-ray diffraction analysis. A linear decrease of the lattice parameters with increasing Ga concentration was detected. The photoluminescence (PL) spectra of the CIGSe crystals were dominated by the edge emission band that shifted towards higher energies with increasing Ga content. Moreover, additional deep PL band (below 1.0 eV) appeared for Ga contents above x = 0.21 showing higher relative intensity with increasing Ga content. The effective bandgap energy of the CIGSe monograin powder materials ranged from 1.0 eV to 1.68 eV as the [Ga]/([In] + [Ga]) ratio increased from 0 to 1.0. An efficiency of 12.8% (active area) was obtained with the MGL solar cell based on CuIn1-xGaxSe2 monograin powder with Ga content of x = 0.21.
关键词： Cu(In,Ga)Se2,Solar cell,Crystalline powder,Crystal growth
更新于2025-11-21 10:59:37
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Band gap engineered zinc oxide nanostructures <i>via</i> a sol–gel synthesis of solvent driven shape-controlled crystal growth
摘要： A reliable sol–gel approach, which combines the formation of ZnO nanocrystals and a solvent driven, low shape-controlled, crystal-growth process to form well-organized ZnO nanostructures at temperature is presented. The sol of ZnO nanocrystals showed shape-controlled crystal growth with respect to the solvent type, resulting in either nanorods, nanoparticles, or nanoslates. The solvothermal process, along with the solvent polarity facilitate the shape-controlled crystal growth process, augmenting the concept of a selective adhesion of solvents onto crystal facets and controlling the final shape of the nanostructures. The XRD traces and XPS spectra support the concept of selective adhesion of solvents onto crystal facets that leads to yield different ZnO morphologies. The shift in optical absorption maxima from 332 nm in initial precursor solution, to 347 nm for ZnO nanocrystals sol, and finally to 375 nm for ZnO nanorods, evidenced the gradual growth and ripening of nanocrystals to dimensional nanostructures. The engineered optical band gaps of ZnO nanostructures are found to be ranged from 3.10 eV to 3.37 eV with respect to the ZnO nanostructures formed in different solvent systems. The theoretical band gaps computed from the experimental XRD spectral traces lie within the range of the optical band gaps obtained from UV-visible spectra of ZnO nanostructures. The spin-casted thin film of ZnO nanorods prepared in DMF exhibits the electrical conductivity of 1.14 × 10?3 S cm?1, which is nearly one order of magnitude higher than the electrical conductivity of ZnO nanoparticles formed in hydroquinone and ZnO sols. The possibility of engineering the band gap and electrical properties of ZnO at nanoscale utilizing an aqueous-based wet chemical synthesis process presented here is simple, versatile, and environmentally friendly, and thus may applicable for making other types of band-gap engineered metal oxide nanostructures with shape-controlled morphologies and optoelectrical properties.
关键词： electrical conductivity,ZnO nanostructures,optical band gap,shape-controlled crystal growth,sol–gel synthesis
更新于2025-11-19 16:56:42
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ZnGa2Se4, a nonlinear material with wide mid infrared transparency and good thermomechanical properties
摘要： During the last decades, mid-infrared (3–12 μm) laser sources using crystals with nonlinear optical properties have attracted a particular attention due to their potential applications in different fields such as optical counter-measures and remote chemical sensing. As transparency of common oxide crystals is limited to about 4 μm, many researches have been focused on chalcopyrite compounds because of their wide transparency in the mid-IR range and their strong nonlinear optical coefficients. There is a need of such crystals able to convert efficiently the near infrared wavelengths from commercially available lasers into wavelengths higher than 5 μm through Optical Parametric Oscillators (OPO) systems. This paper presents a new compound: ZnGa2Se4 (ZGSe). Measurements made on dense polycrystals show a high thermal conductivity value in comparison with other selenides (2.9 W m?1 K?1), a wide transparency from visible to beyond the band III of the mid IR (0.6 μm–17 μm) and a coefficient of thermal expansion inferior to 10?5 K?1. These results are very encouraging and improvements of the growth process are now undertaken to obtain single crystals with the required optical quality.
关键词： Optical materials and properties,ZnGa2Se4,Crystal growth,Thermomechanical properties
更新于2025-11-19 16:56:35
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Preparation of α‐Si <sub/>3</sub> N <sub/>4</sub> by direct nitridation using the polysilicon waste by diamond wire cutting
摘要： With the rapid development of the semiconductor industry and solar photovoltaic industry, a large number of polysilicon wastes from diamond wire cutting are accumulated, which not only pollute the environment, but also cause safety problems due to the ultrafine particle size and high reactivity. The diamond wire cutting polysilicon waste was used to prepare α-Si3N4 by direct nitridation method. This method could not only fully recycle the waste and reduce environmental pollution, but also reduce the production cost of α-Si3N4. Furthermore, the effects of FeCl3, NaCl and metal Cu on the nitridation of polysilicon waste are investigated in detail, respectively. It is found that FeCl3 and NaCl are not ideal additives for the preparation of α-Si3N4. However, α-Si3N4 dominated Si3N4 can be obtained via adding 5 wt. % Cu after nitridation at 1250 oC for 8 h, and the relative content of α-Si3N4 reaches 92.37 %.
关键词： silicon nitride,crystal growth,nitridation,catalysts/catalysis,powders
更新于2025-11-14 14:48:53
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Reversed Crystal Growth
摘要： In the last decade, a reversed growth route has been found in many crystal growth processes. In these systems, a single crystal does not develop from a single nucleus. The precursor molecules/ions or nanocrystallites aggregate into some large amorphous or polycrystalline particles. Multiple-nucleation on the surface of the amorphous particles or surface re-crystallization of the polycrystalline particles then takes place, forming a single crystal shell with a regular morphology. Finally, the crystallization extends from the surface to the core to form single crystals. This non-classical crystal growth route often results in some special morphologies, such as core-shell structures, hollow single crystals, sandwich structures, etc. This article gives a brief review of the research into reversed crystal growth and demonstrates that investigation of detailed mechanisms of crystal growth enables us to better understand the formation of many novel morphologies of the crystals. Some unsolved problems are also discussed.
关键词： nucleation,crystal growth,core-shell structure,crystal morphology,hollow crystal,electron microscopy
更新于2025-09-23 15:23:52
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Enhancing Diamond NV Center Density in HPHT Substrate and Epitaxy Lateral Overgrowth Layer by Tungsten Pattern
摘要： The Nitrogen Vacancy (NV) center distribution in epitaxial lateral overgrowth (ELO) single crystal diamond layer grown on tungsten patterned HPHT substrate by microwave plasma chemical vapor deposition (CVD) system has been investigated. It has been found that in ELO diamond layer densities of NV0 and NV- center above the tungsten metal are enhanced. Meanwhile, in patterned high-pressure and high-temperature (HPHT) substrate the density of NV- center beneath the tungsten metal is much higher than that of NV0. The HPHT substrate doesn't contain NV centers before CVD growth, and there is almost no NV center in the region without tungsten metal after growth.
关键词： Defects,Carbon materials,Epitaxial growth,Luminescence,Crystal growth
更新于2025-09-23 15:23:52
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(S)TEM methods contributions to improve the fabrication of InGaN thin films on Si, and InN nanostructures on flat Si and rough InGaN
摘要： The main results of a complete study by Transmission and Scanning-Transmission Electron Microscopies ((S)TEM) are described for (i) InGaN/Si (111) heterostructures in the whole compositional range of the alloys, and (ii) InN quantum dots (InN QDs) directly grown on Si wafers or on relatively rough InGaN/Si (111) templates. The combination of many (S)TEM-based techniques allowed to evaluate different characteristics of the systems under study: (InN QD/) InGaN/Si and InN QD/Si interfaces and crystal qualities, structural and chemical imperfections and other important features. InxGa1-xN thin films are often identified as single-crystalline, very homogeneous in composition, and mostly wurtzite-type, remarkably at any value of x. Also, (S)TEM techniques revealed that the InN nanostructures were hexagonal single crystals, mostly epitaxial to the supporting lattice. The InN crystals also exhibited partially cubic arrangements when allocated onto In-rich InxGa1-xN (i.e. x > 0.7).
关键词： Semiconductors,TEM,Heterojunctions,Crystal structure.,Nitride materials,Crystal growth,Transmission Electron Microscopy
更新于2025-09-23 15:23:52
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Perovskite CsPbBr3 single crystal detector for alpha-particle spectroscopy
摘要： Here we report the first spectroscopic alpha particle detection based on CsPbBr3 detectors with asymmetric contacts. The CsPbBr3 single crystal was grown from the melt using Bridgman method and then fabricated into detectors with different contacts. The In/CsPbBr3/Au detector presented a low dark current density (~100 nA/cm2) and temporal stable performance under high electric field (1000 V/cm). Such detector demonstrated excellent gamma ray resolving capability with a full-width at half maximum (FWHM) of ~5.9 keV for the 57Co 122 keV γ ray. The CsPbBr3 detector was capable of simultaneously resolving both the alpha particle (5.5 MeV) and γ ray (59.5 keV) peaks from 241Am radioactive isotope. The transport properties of CsPbBr3 were then determined based on the alpha particle spectra and corresponding rise time distributions. The equivalent values of electron and hole mobilities were indicated as 63 and 49 cm2/(V·s) respectively. The calculated electron and hole mobility-lifetime products were 4.5 × 10-4 and 9.5 × 10-4 cm2/V, respectively, demonstrating superior transport properties of holes over electrons in CsPbBr3. This work widens the scope of perovskite detectors to encompass charged radiation as well as high energy X/γ rays, and will significantly promote and guide further studies on perovskite materials for radiation detection applications.
关键词： CsPbBr3,Alpha particle detection,Crystal growth,Perovskite single crystal
更新于2025-09-23 15:23:52
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Growth and Optical Characterization of Europium and Cerium Doped KCl Single Crystals by Czochralski Method for Dosimetric Applications
摘要： Rare-earth-doped alkali halide single crystals KCl:Eu, KCl:Ce, and KCl:Eu,Ce were grown from melt using the Czochralski technique, and optical characterization was carried out with the prime focus on dosimetric applications. The grown crystals were investigated using XRD analysis, PL analysis, TSL measurements, and OSL measurements. The XRD of the crystals matched well with ICDD patterns (00-041-1476), and diffraction peaks can be assigned to the KCl structure, indicating that all the crystals have the same structure as KCl. The enhanced intensity of TSL and OSL was observed for co-doping of (Eu, Ce) in KCl crystals as compared to single doping. The appearance of a single glow peak in KCl:Eu,Ce at 230°C compared to single-doped KCl:Ce crystals suggested the use of the material in TL dosimetry. The intensity of OSL also showed a two-fold increase compared to single-doped crystals, suggesting its use in OSL dosimetry. PL studies showed a very high enhancement of intensity in Eu2+ emissions, reaching a maximum of about 421 nm in the (Eu2+, Ce3+) co-doped crystal compared to single-doped crystals. This justifies the occurrence of energy transfer from Ce3+ to Eu2+ in the KCl host lattice. These results showed that KCl:Eu,Ce acts as a potential TL and OSL dosimeter due to its high sensitivity to ionizing radiation.
关键词： crystal growth,Single crystal,potassium chloride,optical characterization,Czochralski method
更新于2025-09-23 15:23:52
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Structural and vibrational properties of PVT grown BiTeCl microcrystals
摘要： High-quality BiTeCl microcrystals are grown by the physical vapor transport (PVT) method without using a foreign transport agent. The plate-like microcrystals with a developed (0001) surface are up to ~500 μm in diameter. The grown crystal phase composition was identified by the X-ray single crystal structure analysis in space group P63mc: a = 4.2475(6) ?, c = 12.409(2) ?, Z = 2 (R = 0.0343). The BiTeCl microcrystal phase purity was verified by Raman microspectrometry under excitation at λ = 632.8 and 532.1 nm.
关键词： PVT crystal growth,crystal structure,topological insulator,SEM,BiTeCl,Raman spectroscopy
更新于2025-09-23 15:23:52