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European Microscopy Congress 2016: Proceedings || The microstructure of ZnSnO and its correlation to electrical and optical properties
摘要： Over the last years, the interest in the field of transparent conductive oxides (TCOs) has grown dramatically due to their wide applicability and improved properties that may be reached when incorporating these materials into devices. TCOs are mainly used in the industry of low-emissivity windows, flat panel displays, light emitting diodes and photovoltaics [1]. For photovoltaic applications, the main purpose of TCOs is to let light enter into the solar cell and to extract the electric charges allowing them to be drifted towards the electric contacts. Therefore, it is necessary for these materials to be as transparent and as conductive as possible [2]. Ideally, TCOs should be indium-free, as indium is scarce and hence expensive [3]. The goal is therefore to optimize a material that is earth-abundant, low-cost and with good electrical and optical properties. As many steps in photovoltaic device fabrication require a high temperature, a crucial requisite for TCOs is also thermal stability. Based on these criteria, an amorphous compound of Zn-Sn-O (ZTO) deposited by sputtering was selected for the present study [4]. The microstructure of ZTO is known to strongly influence its electrical and optical properties, as well as its thermal stability. In that regard, transmission electron microscopy (TEM), in situ X-ray diffraction (XRD) experiments and conventional electrical and optical characterization were performed to assess the links between annealing treatments, ZTO microstructure and optical and electrical properties. First, samples were annealed in air, in an oven up to 150 and 500 °C and then investigated by transmission electron microscopy. While electrical and optical properties were measured to change significantly upon annealing, no major microstructural change was observed in TEM images. In situ theta-2theta XRD experiments were then performed by increasing the temperature up to 1000-1200°C in air and vacuum. Substrates resistant to these temperatures were employed, namely fused silica and sapphire. Different heating rates were used, ranging from 3°C/min up to 10°C/min. The XRD results (Fig.1) demonstrate that the amorphous phase is stable up to >500 °C when annealed in air and > 900 °C when annealed in 10-4 mbar, hence highlighting a strong influence of the annealing atmosphere on the crystallisation temperature. Rutile SnO2 is the first phase to crystallize and remains the main crystal structure observed throughout the whole process, with Al2ZnO4 forming at higher temperatures as a result of an interaction between the TCO layer and the sapphire substrate. Electrical properties were measured to decrease after annealing, with TEM measurements demonstrating that Zn migration at high temperature leads to the formation of a defective crystalline structure (Fig.2). This effect is more severe when annealing in air when compared to vacuum conditions. Indeed, the presence of oxygen in the surrounding atmosphere facilitates the formation of crystalline SnO2, a process that repeals Zn atoms to grain boundaries and surfaces of the TCO layer (Fig.3). On the other hand, the formation of crystalline SnO2 and the release of zinc are both delayed when annealing in vacuum. In general, crystallisation and Zn evaporation are observed to be detrimental to the electrical properties as it leads to the formation of voids in the structure. On a technological level, the high thermal stability of the defect-free amorphous ZTO microstructure in oxygen-poor atmospheres may enable its application in high efficiency photovoltaic architectures.
关键词： TEM,XRD,crystallization kinetics,transparent conductive oxides
更新于2025-09-23 15:21:21
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Structure and Crystallization of Glasses in the MnNbOF5–BaF2–InF3 System
摘要： Glasses of the MnNbOF5–BaF2–InF3 system were prepared. The structure, thermal behavior, and crystallization of these glasses were studied by IR and Raman spectroscopy, differential scanning calorimetry (DSC), X-ray powder diffraction, and microscopy. The ions form a mixed glass network. Glass crystallization occurs in one or two steps depending on the component ratio. The major crystal phases are Ba3In2F12 and BaNbOF5. The obtainability of transparent crystal-glass samples in MnNbOF5–BaF2–InF3 glasses via heat treatment is shown.
关键词： fluoride glasses,structure,crystallization,oxyfluoride glasses
更新于2025-09-23 15:21:21
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Phase Change Behavior of Sn <sub/>20</sub> Sb <sub/>80</sub> /Si?Nano-Composite Multilayer?Thin?Films
摘要： Nano-composite multilayer Sn20Sb80/Si thin films were studied by thermal, electrical and optical methods. Compared with Sn20Sb80, Sn20Sb80/Si film was proved to be a more promising candidate for phase change memory device applications because of its higher crystallization temperature (246?C) and larger crystallization activation energy (2.6 eV). The bandgap was broadened with the increase of Si layer thickness. The crystallization of Sn20Sb80 was restrained after the adding of more Si film layers confirmed by X-ray diffraction patterns. A smoother surface was obtained with the root-mean-square surface roughness of 0.753 nm for [Sn20Sb80(3nm)/Si(7nm)]5 thin film. The measurement using the picosecond laser technique showed that [Sn20Sb80(3nm)/Si(7nm)]5 thin film could achieve the crystalline-to-amorphous phase transform within 2.8 ns irradiated by the laser pulse.
关键词： bandgap,nano-composite multilayer thin films,picosecond laser technique,crystallization activation energy,Phase change memory,surface roughness,Sn20Sb80/Si,crystallization temperature
更新于2025-09-23 15:21:01
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Oriented Crystallization of Mixeda??Cation Tin Halides for Highly Efficient and Stable Leada??Free Perovskite Solar Cells
摘要： As the most promising lead-free branch, tin halide perovskites suffer from the severe oxidation from Sn2+ to Sn4+, which results in the unsatisfactory conversion efficiency far from what they deserve. In this work, by facile incorporation of methylammonium bromide in composition engineering, formamidinium and methylammonium mixed cations tin halide perovskite films with ultra-highly oriented crystallization are synthesized with the preferential facet of (001), and that oxidation is suppressed with obviously declined trap density. MA+ ions are responsible for that impressive orientation while Br- ions account for their bandgap modulation. Depending on high quality of the optimal MA0.25FA0.75SnI2.75Br0.25 perovskite films, their device conversion efficiency surges to 9.31% in contrast to 5.02% of the control formamidinium tin triiodide perovskite (FASnI3) device, along with almost eliminated hysteresis. That also results in the outstanding device stability, maintaining above 80% of the initial efficiency after 300 h of light soaking while the control FASnI3 device fails within 120 h. This paper definitely paves a facile and effective way to develop high-efficiency tin halide perovskites solar cells, optoelectronic devices, and beyond.
关键词： trap density,methylammonium bromide,oriented crystallization,tin halide perovskites,divalent tin ions
更新于2025-09-23 15:21:01
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SiO<sub>2</sub> nanoparticle-regulated crystallization of lead halide perovskite and improved efficiency of carbon-electrode based, low temperature planar perovskite solar cells
摘要： SiO2 nanoparticles were used to regulate the crystallizing process of lead halide perovskite film that prepared by the sequential deposition method, which was used in the low temperature processed, carbon-electrode basing, hole-conductor-free planar perovskite solar cells. It was observed that, after adding small amount of SiO2 precursor (1% in volume ratio) into the lead iodide solution, performance parameters of open-circuit voltage, short-circuit current and fill factor were all upgraded, which helped to increase the power conversion efficiency (reverse scan) from 11.44(±1.83)% (optimized at 12.42%) to 14.01(±2.14)% (optimized at 15.28%, AM 1.5G, 100 mW/cm2). Transient photocurrent decay curve measurements showed that, after the incorporation of SiO2 nanoparticles, charge extraction was accelerated, while transient photovoltage decay and dark current curve tests both showed that recombination was retarded. The improvement is due to the improved crystallinity of the perovskite film. X-ray diffraction and scanning electron microscopy studies observed that, with incorporation of amorphous SiO2 nanoparticles, smaller crystallites were obtained in lead iodide films, while larger crystallites were achieved in the final perovskite film. This study implies that, amorphous SiO2 nanoparticles could regulate the coarsening process of the perovskite film, which provides an effective method in obtaining high quality perovskite film.
关键词： SiO2 (61.46.Hk),crystallization(81.10.-h),low temperature(84.60.Jt),perovskite solar cell(88.40.H-),lead iodide(61.82.Rx),carbon-electrode(88.40.HJ)
更新于2025-09-23 15:21:01
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Unraveling the impact of hole transport materials on photostability of perovskite films and p-i-n solar cells
摘要： We investigated the impact of a series of hole transport layer materials (HTLs) such as PEDOT:PSS, NiOx, PTAA, and PTA on photostability of thin films and solar cells based on MAPbI3, Cs0.15FA0.85PbI3, Cs0.1MA0.15FA0.75PbI3, Cs0.1MA0.15FA0.75Pb(Br0.15I0.85)3, and Cs0.15FA0.85Pb(Br0.15I0.85)3 complex lead halides. Mixed halide perovskites showed reduced photostability in comparison with similar iodide-only compositions. In particular, we observed light-induced recrystallization of all perovskite films except MAPbI3 with the strongest effects revealed for Br-containing systems. Moreover, halide and β FAPbI3 phase segregations were also observed mostly in mixed-halide systems. Interestingly, coating perovskite films with PCBM layer spectacularly suppressed light-induced growth of crystalline domains as well as segregation of Br-rich and I-rich phases or β FAPbI3. We strongly believe that all three effects are promoted by the light-induced formation of surface defects, which are healed by adjacent PCBM coating. While comparing different hole-transport materials, we found that NiOx and PEDOT:PSS are the least suitable HTLs due to their interfacial (photo)chemical interactions with perovskite absorbers. On the contrary, polyarylamine-type HTLs PTA and PTAA form rather stable interfaces, which makes them the best candidates for durable p-i-n perovskite solar cells. Indeed, multilayered ITO/PTA(A)/MAPbI3/PCBM stacks revealed no aging effects within 1000 h of continuous light soaking and delivered stable and high power conversion efficiencies in solar cells. The obtained results suggest that using polyarylamine-type HTLs and simple single-phase perovskite compositions paves a way for designing stable and efficient perovskite solar cells.
关键词： stable HTL/perovskite interface,interface-induced degradation,light-induced perovskite crystallization,photo-induced degradation,p-i-n perovskite solar cells
更新于2025-09-23 15:21:01
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[IEEE 2019 Compound Semiconductor Week (CSW) - Nara, Japan (2019.5.19-2019.5.23)] 2019 Compound Semiconductor Week (CSW) - Structural and optical properties of GaAs film grown on a glass substrate using a large-grained Ge seed layer for solar cell applications
摘要： We fabricate a light absorbing GaAs layer on a glass substrate using a Ge seed layer formed by Al-induced crystallization. The GaAs layer grown at 520 °C exhibits the grain size of 50 μm and the internal quantum efficiency of 60% with a bias voltage of 1.0 V. These values are the largest among the GaAs layers grown on amorphous substrates at low temperatures (< 600 °C).
关键词： Al-induced crystallization,GaAs epitaxy,Thin film solar cell
更新于2025-09-23 15:21:01
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Carbon Nanotubes - Recent Progress || Stability and Reliability of an Electrical Device Employing Highly Crystalline Single-Walled Carbon Nanotubes as a Field Emitter
摘要： Carbon nanomaterial is drawing keen interest from researchers as well as materials scientists. Carbon nanotubes (CNTs)—and their nanoscale needle shape—offering chemical stability, thermal conductivity, and mechanical strength exhibit unique properties as a quasi-one-dimensional material. Among the expected applications, field emission electron sources appear the most promising industrially and are approaching practical utilization. However, efforts to construct a field emission (FE) cathode with single-walled carbon nanotubes (SWCNTs) have so far only helped average out a non-homogeneous electron emitter plane with large FE current fluctuations and a short emission life-time because they failed to realize a stable emission current owing to crystal defects of the carbon network in CNTs. The utilization of CNTs to obtain an effective cathode, one with a stable emission and low FE current fluctuation, relies on the ability to disperse CNTs uniformly in liquid media. In particular, highly crystalline SWCNTs hold promise to obtain good stability and reliability. The author successfully manufactured highly crystalline SWCNTs-based FE lighting elements that exhibit stable electron emission, a long emission life-time, and low power consumption for electron emitters. This FE device employing highly crystalline SWCNTs has the potential for conserving energy through low power consumption in our habitats.
关键词： wet coating process,high crystallization,field emission,single-walled carbon nanotube,scratch,thin film,planar light source,cathode luminescence
更新于2025-09-23 15:21:01
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On the Formation of Amorphous Ge Nanoclusters and Ge Nanocrystals in GeSixOy Films on Quartz Substrates by Furnace and Pulsed Laser Annealing
摘要： Nonstoichiometric GeO0.5[SiO2]0.5 and GeO0.5[SiO]0.5 germanosilicate glassy films are produced by the high-vacuum coevaporation of GeO2 and either SiO or SiO2 powders with deposition onto a cold fused silica substrate. Then the films are subjected to furnace or laser annealing (a XeCl laser, λ = 308 nm, pulse duration of 15 ns). The properties of the samples are studied by transmittance and reflectance spectroscopy, Raman spectroscopy, and photoluminescence spectroscopy. As shown by analysis of the Raman spectra, the GeO[SiO] film deposited at a substrate temperature of 100°C contains amorphous Ge clusters, whereas no signal from Ge–Ge bond vibrations is observed in the Raman spectra of the GeO[SiO2] film deposited at the same temperature. The optical absorption edge of the as-deposited GeO[SiO2] film corresponds to ~400 nm; at the same time, in the GeO[SiO] film, absorption is observed right up to the near-infrared region, which is apparently due to absorption in Ge clusters. Annealing induces a shift of the absorption edge to longer wavelengths. After annealing of the GeO[SiO2] film at 450°C, amorphous germanium clusters are detected in the film, and after annealing at 550°C as well as after pulsed laser annealing, germanium nanocrystals are detected. The crystallization of amorphous Ge nanoclusters in the GeO[SiO] film requires annealing at a temperature of 680°C. In this case, the size of Ge nanoclusters in this film are smaller than that in the GeO[SiO2] film. It is not possible to crystallize Ge clusters in the GeO[SiO] film. It seems obvious that the smaller the semiconductor nanoclusters in an insulating matrix, the more difficult it is to crystallize them. In the low-temperature photoluminescence spectra of the annealed films, signals caused by either defects or Ge clusters are detected.
关键词： crystallization,pulsed laser annealing,germanosilicate glasses,germanium nanoclusters
更新于2025-09-23 15:21:01
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Particulars of Femtosecond Laser Modification of Antimony-Silicate Glass
摘要： The particulars of the effect of focused femtosecond laser pulses on antimony silicate glass with the composition 25Sb2O3–75SiO2 % (molar content) in thermal and athermal regimes were studied. It was found that in contrast to quartz, alkali silicate, and some borosilicate glasses the birefringence of the form characteristic for the formation of nanogratings does not arise in the laser-modified zones of the studied glass. Weak birefringence with slow axis parallel to the polarization plane of the writing laser beam, accompanied by precipitation of crystalline phases, seemingly including the cubic modification of Sb2O3, arises in the modified zones under irradiation by 106 pulses with energy > 100 nJ and repetition frequency 10 and 200 kHz.
关键词： senarmontite,Raman scattering spectroscopy,crystallization,antimony silicate glass,femtosecond laser modification
更新于2025-09-23 15:21:01