A comparative study of different emitter diffusion profiles on the performance of Si solar cells

We have investigated the effect of emitter design key parameters such as depth factor and the peak concentration for different types of emitter diffusion profiles (uniform, exponential, Gaussian, and Erfc) on the performance of silicon (Si) solar cells. The value of the depth factor is optimized as 0.1 µm for all these emitter diffusion profiles. Afterward, the peak concentration value is optimized for all the diffusion profiles. A close examination of relative diffusion lengths, conductivities, recombination rates, internal and external quantum efficiencies for these diffusion profiles revealed that among all the considered emitter diffusion profiles, the Erfc profile exhibits the maximum efficiency of 23.53% with an optimized peak concentration of 2×1020 cm-3 for emitter and 1×1019 cm-3 for the back surface filed doping. PC1D was used for all the simulations.

SEEDING to enable sensitive electrochemical detection of biomarkers in undiluted biological samples

The interface between an electrode and a liquid plays a critical role in the overall performance of electrochemical biosensors. Surface morphology and roughness affect key parameters, such as the active area, diffusion profiles, and apparent electron transfer kinetics, whereas porosity may hinder the diffusion of fouling proteins. However, there is no simple and rapid method compatible with photolithographic electrodes to generate both nanostructured and porous surfaces. Herein, we demonstrate the interplay between the preferential etching of chloride and surfactant-assisted anisotropic gold reduction to create homogeneous, nanostructured, and nanoporous substrates on photolithographic gold electrodes within a minute and without using templates. We coined this process, SEEDING, that is, Surfactant-based Electrochemical Etch-Deposit Interplay for Nanostructure/Nanopore Growth. SEEDING on electrodes enhanced the sensitivity and anti-biofouling capabilities, enabling direct analysis of small molecules, proteins, and cancer-derived extracellular vesicles in complex biological fluids such as undiluted plasma and urine samples.

Confirmation of slow Ti diffusion in quartz by diffusion couple experiments and evidence from natural samples

Titanium diffusion profiles in natural quartz crystals have become an increasingly popular tool to reconstruct the time scales of various magmatic, metamorphic, and hydrothermal processes. However, the original calibration of Ti diffusion rates in quartz has recently been challenged, and diffusivities were found to be about three orders of magnitude lower. We performed annealing experiments on crystal-crystal diffusion couples consisting of Ti-free synthetic quartz seeds over which Ti-rich quartz (100–3000 μg/g Ti) was grown hydrothermally. The annealing experiments were performed at 1000–1600 °C and 0.1 MPa to 2.0 GPa, and they lasted for 3–84 days. The resulting diffusion profiles were mapped by cathodoluminescence (CL), transmission electron microscope–energy-dispersive X-ray spectroscopy (TEM-EDXS), and, for the first time, by helium ion microscope–secondary ion mass spectrometry (HIM-SIMS). Obtained diffusion coefficients range from values similar to the lower range in previous research to values up to two orders of magnitude lower. In addition, inversely zoned quartz and sanidine phenocrysts in a natural rhyolite were studied. Comparison of the diffusion profiles suggests that at ~735 °C, the Ti diffusivity in quartz is ~1.5 and 3.0 orders of magnitude lower than that of Ba and Sr, respectively, in sanidine. The combined evidence confirms that Ti diffusion in quartz is very slow, potentially even slower than proposed earlier. Consequently, previous time scales derived from Ti diffusion profiles in quartz are likely orders of magnitude too short, and further experiments are necessary to fully clarify the issue.

Er3+/ Yb3+ Doped Active Optic Y Splitter Realized by Diffusion Waveguides with Ag+ - Na+ Ion Exchange

We reported on the active channel waveguides, formed in novel types of silicate glasses, doped with rare-earth elements, and Zn were investigated. The silicate glass GZ4 with Er 3+ and Yb 3+ content was studied, and the best doping ratio was estimated about luminescent properties. The composition of the glass samples (GZ4) with the content of 0.25 at. % Er 3+ and 5.0 at. % Yb 3+ and Zn 4.0 at. % resp. 5.6 at. % Zn was optimized. This glass was evaluated as the most suitable material for integrated amplifiers in the telecommunication band of 1 530 – 1 565 nm. Other samples were prepared with an active channel waveguides and active planar optical power splitter Y with a splitting ratio of 1x2 by two-step ion-exchange Na + -Ag + . Diffusion profiles of the created samples were analyzed by the EMA microscope and compared with the near mode-field distribution measurement results. Afterward, the amplification properties of the designed structures were studied, and the differential gain from 1.2 to 1.6 dB (0.48 to 0.64 dB/cm) was achieved by pumping 200 mW at 980 nm.

Paroxysms at Stromboli Volcano (Italy): Source, Genesis and Dynamics

Deciphering the triggering mechanisms of violent explosive activity is of broad interest for understanding the dynamics of basaltic open-vent volcanic systems. For nearly 1300 years Stromboli has been renowned not only for its continuous degassing activity and mild explosions at the summit craters, but also for short-lived, violent explosive events of variable scale, known as major explosions and paroxysms. Here, we focus on the 1456 and 1930 paroxysms and on the most recent events, in July and August 2019 at Stromboli. We show that shallow phenomena such as flank collapse, lava outpouring through fractures opening, or partial emptying of the shallow conduit, only speed up volatile-rich magma ascent by increasing the decompression rate, whereas pressurization of the crustal system and the deep refilling by magma and its CO2-rich gas phase play a major role in triggering paroxysms. Moreover, we present new data on the geochemistry of the 2019 bulk pumice, along with a compilation of data from the literature, chemical profiles in olivine crystals, and the physical parameters of explosive eruptions of wide ranging magnitude and intensity. For small and large paroxysms, timescales were derived from Fe–Mg diffusion profiles in olivine. In both types of explosion, the last phases of crystallization-diffusion indicate rapid magma ascent rates of two to ten days prior to eruption. Trace element concentrations (Nb, La and Ba) and ratios (Rb/Th) indicate that the 2019 pumice samples plot in the domain of magma batches erupted within the last 20 years at Stromboli. As a whole, there is no correlation between magma geochemistry and magnitude or intensity of explosive eruptions, which span a range of ∼3 orders of magnitude (from major explosions to large paroxysms) based on estimates of erupted tephra volumes. In contrast, olivine compositions are a good proxy for erupted tephra volumes and magma flux. The correlation among physical and chemical parameters, which is valid for the overall spectrum of eruptions, implies that the magmatic source ultimately controls eruptive dynamics.

Assessing analytical convolution effects in diffusion studies: Applications to experimental and natural diffusion profiles

Given that all in-situ analytical techniques have a non-zero beam size, all measured profiles, resulting from diffusion or otherwise, will be artefactually elongated to some degree. Profiles where the total length over which the concentration changes approaches the resolution of the analytical technique likely suffer from serious convolution; the measured profiles may be considerably elongated relative to the true profile. Resolving this effect is non-trivial, except for some specific combinations of profile type and beam geometry. In this study, a versatile method for numerically deconvoluting diffusion profiles acquired using techniques with Gaussian, Lorentzian, (pseudo-)Voigt, circular/elliptical or square/rectangular interaction volumes, is presented. A MATLAB code, including a user-friendly interface (PACE-the Program for Assessing Convolution Effects in diffusion studies), is also provided, and applied to several experimental and natural profiles interpreted as resulting from diffusion, showing various degrees of convolution.