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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Evaluation of localized vertical current formation in carrier selective passivation layers of silicon solar cells by conductive AFM
摘要： Carrier selective contacts are of growing interest in the development and optimization of high efficiency silicon solar cell concepts. In particular, the passivation mechanism of ultra-thin oxide layers in interaction with poly-Si layers came into focus and the origin of tunnel currents and the so called pinhole conductivity is discussed. Many process parameters and their influence on the passivation effect are not clear, yet. The present study investigates the electrical properties in Si/SiOx/poly-Si layer system from different processes. For this purpose, high-resolution electrical evaluation of the current path density through the interfacial oxide is investigated by conductive AFM using a newly developed image calculation software tool to determine the vertical current path density. We compared two thicknesses of poly-Si (n+ PECVD) layers each at optimum annealing temperature (corresponding to highest i-VOC). The influence of three annealing temperatures (at optimum passivation, below and above) is investigated for an ozone oxide and pinhole densities are analyzed by the TMAH method. Finally, the optimum properties of the layer stack for three interfacial oxides (each at optimum passivation) are studied.
关键词： silicon solar cells,pinhole conductivity,passivation layers,carrier selective contacts,conductive AFM
更新于2025-09-16 10:30:52
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A Comparative Investigation of Plasmonic Properties between Tunable Nanoobjects and Metallized Nanoprobes for Optical Spectroscopy
摘要： In order to evaluate the optical efficiency of tip-based probes for future tip-enhanced optical spectroscopy applications, we have developed an experimental setup based on the coupling of an achromatic inverted microscope equipped with a total internal reflection objective and an atomic force microscopy (AFM) head. This spectroscopic tool has been validated using individual nanofabricated antennas (gold nanodisks/nanocones) on a glass substrate, which act as nanoresonators based on localized surface plasmons. Spectrally tunable transverse electric and magnetic plasmonic resonances are identified and are in excellent agreement with numerical calculations performed as a function of the nano-antenna geometry and size. We have investigated a series of state-of-the-art gold-coated AFM probes, which are commonly used for tip-enhanced (Raman spectroscopy) optical experiments. Their scattering spectrum consists of resonances depending on the tip sharpness or granularity superimposed on a broad emission spectrum due to semi-infinite metal layer acting as a non-resonant antenna. From the comparison between the plasmonic response of both types of optical antennas, a new generation of probes for tip-enhanced optical spectroscopy is proposed, in which single plasmonic nano-antennas are engineered at the apex of a non-metallic AFM tip. As from numerical simulation results, such tips would ensure a spectral tunability as a function of the material, size, and geometry, together with expected high enhancement factors. Such features would allow the design of spectrally tunable surface enhanced Raman spectroscopy substrates, and should be a reliable and efficient alternative to tips commonly used in tip-enhanced optical spectroscopy experiments such as tip-enhanced Raman spectroscopy.
关键词： Optical Spectroscopy,Plasmonics,TERS,Nano-antennas,AFM
更新于2025-09-12 10:27:22
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The passivity of selective laser melted 316L stainless steel
摘要： The passive film properties of as-received selective laser-melted 316L stainless steel (SLMed 316L SS) without obvious pores were studied and compared with those of wrought and solution-annealed (SA) SLMed 316L SSs. Among the samples, the as-received SLMed 316L SS had the lowest passive current density, which was attributed to two factors: the super high sub-grain boundary density increased the number of nucleation sites for passive film formation, and the micro-galvanic effect between the sub-grain boundary and the inner sub-grains also accelerated the rapid formation of a thick protective layer. The poor passivation and re-passivation abilities of the SA SLMed 316L SS were ascribed to the extensively precipitated nanosized oxide and sulfide particles, especially those at the grain boundary.
关键词： Cellular structure,Passive film,Stainless steel,Selective laser melting,AFM
更新于2025-09-12 10:27:22
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ZnO nano-sized particles preparation by laser ablation in liquids
摘要： In this paper, we used laser ablation in liquids to prepare ZnO nanoparticles. In our experiment, the pulsed laser was focused onto the Zn target submerged in water. We used di?erent laser energy to form the ZnO nanoparticles. The size, structure and photoluminescence spectra of ZnO nanoparticles were displayed by using XRD and AFM. The relationship between diameter of ZnO nanoparticles and laser energy was analyzed. In addition, we also studied the variation of photoluminescence spectra of ZnO nanoparticles with di?erent laser energy.
关键词： Laser ablation in liquids,XRD,ZnO nanoparticles,AFM
更新于2025-09-12 10:27:22
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Atomic Force Microscope Guided SERS Spectra Observation for Au@Ag-4MBA@PVP Plasmonic Nanoparticles
摘要： Recently polymer encapsulated surface-enhanced-Raman-scattering (SERS) probes with internal noble metal core–shell structure has found growing applications in biomedical applications. Here we studied the SERS spectra of Au@Ag–4MBA@PVP (4MBA: 4-mercaptobenzoic acid; PVP: polyvinylpyrrolidone) plasmonic nanoparticles produced from a chemical reduction method. By linking the atomic force microscope (AFM) with the homebuilt confocal Raman spectrometer thus to use AFM images as guidance, we realized the measurement of the SERS spectra from separated nanoparticles. We investigated the cases for single nanoparticles and for dimer structures and report several observed results including SERS spectra linearly scaled with laser power, abrupt boosting and abnormal shape changing of SERS spectra for dimer structures. Based on the finite element method simulation, we explained the observed ratio of SERS signals between the dimer structure and the single nanoparticle, and attributed the observed abnormal spectra to the photothermal effect of these plasmonic nanoparticles. Our study provides valuable guidance for choosing appropriate laser power when applying similar SERS probes to image biological cells.
关键词： SERS probes,AFM imaging,confocal Raman spectrometer,SERS spectra,photothermal effect,plasmonic nanoparticles
更新于2025-09-11 14:15:04
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Investigation on structural, optical and photovoltaic properties of Barium doped cuprous oxide thin films by nebulizer spray technique
摘要： In present work, pure and barium (Ba) doped cuprous oxide (Cu2O) films are coated on heated glass substrate by Nebulizer spray technique (NST) by taking different doping concentration (0%, 3%, 5%, and 7%) of Ba. The XRD, AFM, optical, electrical resistivity and solar cell studies of pure and Ba doped samples were discussed. The XRD pattern confirms the polycrystalline cubic structure with a preferred (111) plane orientation. Atomic force microscopy (AFM) reveals the spherical shape nano particles. The Raman analysis confirmed the cuprous oxide phase of prepared films. The Optical analysis was revealed the decreasing in band gap with increasing barium doping concentration. The photoluminescence studies confirmed the single emission peak obtained at 630 nm for all the films corresponds to Cu2O phase. The electrical resistivity is found to be 0.45 × 102 Ω cm for 7% Ba doped Cu2O thin film and the photovoltaic properties of the fabricated solar cell i.e. FTO/n-ZnO/p-7% Ba:Cu2O/Ag was formed for 7% Ba: Cu2O thin film. Further, the efficiency of the fabricated solar cell is found to be 0.85%.
关键词： solar cell,Barium doped,AFM studies,spray pyrolysis,electrical measurements
更新于2025-09-11 14:15:04
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Micron-Sized Constrictions Fabricated Using the Femtosecond Laser Technique on YBCO Thin Films
摘要： In this paper, I report on the fabrication of micron-sized constrictions in YBCO thin films using the femtosecond laser technique. The constrictions are S-shaped superconducting weak links fabricated on YBCO thin films. The constrictions show a measurable superconducting current flowing through them. Current-voltage (I–V) characteristics were used to determine the critical current IC of the constrictions at 77 K. The width of the constrictions was determined at the narrowest point using SEM (scanning electron microscope). Three micron-sized constrictions were fabricated with a width of 2.88 μm, 1.72 μm, and 1.69 μm and a length of 5 μm. Based on the width and length of these constrictions in relation to the coherence length (ξ) of the YBCO, these constrictions should conduct supercurrent by Abrikosov vortices. The SEM images show that the femtosecond laser heats the samples beyond the geometric boundary, damaging some of the superconductive phases of the YBCO constrictions. As a result, the constrictions conduct current by one-dimensional depairing.
关键词： Atomic force microscope (AFM),Abrikosov vortices,Flux pinning,YBCO thin film,Lasers,Critical currents,Scanning electron microscopy (SEM)
更新于2025-09-11 14:15:04
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Linewidth calibration using a metrological atomic force microscope with a tip-tilting mechanism
摘要： The linewidth or critical dimension (CD) of a nanoscale line pattern is calibrated using a metrological atomic force microscope with a tip-tilting mechanism (tilting-mAFM). The tilting tip allows scanning of the line pattern’s vertical sidewalls. The tilting-mAFM performs two measurements on each side of the line pattern, and two datasets are stitched together to reconstruct the complete shape of the line pattern. Further, CD is measured based on this pattern. A linewidth standard with a subnanometer-scale uncertainty was used as a target sample to verify this CD calibration procedure. The calibrated CD using tilting-mAFM was 111.2 nm with an expanded uncertainty of 1.0 nm, which was the smallest uncertainty that was observed among the CD measurements that were reported using the tilting-AFM instruments. Further, the difference of this CD value from the reference CD was only 0.2 nm. The results reveal that tilting-mAFM can be used for CD metrology with a single-nanometer accuracy.
关键词： metrological AFM,critical dimension (CD),calibration,tilting-AFM,nanometrology,linewidth
更新于2025-09-10 09:29:36
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Fabrication and Characterization of Superconducting Bilayer (Al/Ti) Transition-Edge Sensor Bolometer Array
摘要： A four-by-four transition-edge sensor (TES) bolometer array based on an Al/Ti bilayer on an Si3N4 substrate for thermal connection, showing an unbiased transition temperature of 1.2 K, was fabricated and characterized. Formation of the Al/Ti bilayer with tetragonal structure was confirmed by x-ray diffraction analysis. The surface roughness of 3.11 nm calculated by atomic force microscopy was found to be negligible compared with the particle size (19.66 nm), indicating a smooth surface. The smoothness of the resistance–temperature (R–T) curve corresponds to the smoothness of the surface of the bilayer sensor, and the superconducting transition curve of the suspended bilayer TES was designed with a biased Tc of 0.45 K and DTc = 2 mK. Such TES bolometer arrays are suitable for astrophysical observations and are extensively used in cosmic microwave background polarization detection.
关键词： AFM,sensor,bolometer,XRD,TES
更新于2025-09-10 09:29:36
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Dynamics of surface evolution of rutile TiO <sub/>2</sub> (110) after ion irradiation
摘要： The dynamics of TiO2 surfaces evolving under 60 keV Ar+ ions have been explored here. Dynamic scaling ansatz, height–height correlation (HHC) model and power spectral density (PSD) model have been applied to investigate the growth mechanisms. The surfaces are growing under non-equilibrium growth processes and three separate domains of evolution have been noticed. Early time growth of the surfaces can be characterized by roughness exponent, α ～ 0.72–0.74, and growth exponent, β ～ 0.3. Dominance of diffusion is also noticed with Edward Wilkinson (EW) growth scaling. In the next time regime, non-local instabilities get incorporated, due to sputter-induced nanostructuring of the surfaces, resulting in a rapid surface roughening with a high value of β. The surface roughness saturates in late time regime.
关键词： height–height correlations,TiO2,power spectral density,AFM
更新于2025-09-10 09:29:36