A thermal anemometer was industrially fabricated without any preprocessing, coprocessing, or postprocessing for the first time. The total sensor footprint is only 0.245 mm(2) using TSMC's 65-nm CMOS process. The dual-mode anemometer measures wind speeds up to 1.2 m/s with a precision of 3.1% (or 0.037 m/s) calorimetrically. Alternatively, using the second hot-element mode, the sensor measures in the range of 0-7.5 ms(-1) with a 0.1 m/s accuracy and an average 1.34% precision. This is the first industrially fabricated thermopile-based CMOS anemometer, paving the way for a compact foundry SoC with inbuilt underlying computing for low-cost air speed monitoring.

A micro-fabricated silicon-based anemometer has been improved by employing a differential calorimetric measurement technique, while additional sensing information is extracted from the constant temperature heater. This combination improves the measurement range, as established experimentally and supported by finite element simulations. The straight-forward three mask fabrication process is also presented. The use of a lock-in amplifier to read out the sensing elements also provides additional information on the wind direction contained in the phase shift. With this information and theoretical basis, the combined anemometer leads to an increased measurement range and an improved <1% full-scale precision.

Spectroscopic ellipsometry of tin (Sn) thin island films on silicon (Si) is investigated to enable monitoring of the progress of deposition and etching. Since our applications only require a measure of the quantity of Sn, we consider here a fit model with low complexity. The trade-offs are high fit speed, the avoidance of complex input requirements, and broad compatibility with instrument software. The model describes the island film as an effective layer with a Lorentzian dielectric function, for which the effective (or “optical”) thickness is obtained. The key question in this paper is how this thickness can be interpreted. For experimental layers, the optical thicknesses are found to be linearly proportional to the actual tin mass thicknesses determined using x-ray fluorescence. The proportionality constant varies from 1.6 ± 0.2 for tin on hydrogenated silicon (Si:H) to 2.33 ± 0.11 on thermal SiO2. Analysis of data simulated with the Bedeaux–Vlieger model relates this major trend to differences in the island shape. Furthermore, the optical thickness from in situ data during a deposition shows a near-linear increase for hemispherical islands on Si:H, and a nonlinear increase for (nearly) full spheres on SiO2. The simulations relate this minor effect to island-island interactions that depend on island coverage and shape. It is concluded that the optical thickness is a usable measure to monitor the quantity of Sn on Si:H during a process. For Sn on SiO2, the model provides a more qualitative indication of whether growth or etching occurs.

This study presents an inline-compatible technique based on reflectance spectroscopy for characterizing both the thickness and crystalline volume fraction of polysilicon (poly-Si) layers in tunnel oxide passivated contact solar cell precursors, serving as an intermediate characterization step suitable for production and process control. An optical model based on the Fresnel equations and the transfer-matrix method is used to simulate the reflectance of a poly-Si layer on a planar silicon substrate quantitatively. The Bruggeman effective medium approximation is used to define poly-Si as crystalline silicon particles dispersed in an amorphous silicon matrix. By treating the poly-Si layer thickness and crystalline volume fraction as fit parameters, estimates of these values can be obtained from the measured inline reflectance spectra using the developed optical model. The estimated thicknesses and the crystalline volume fractions show a good correlation with the reference thickness values measured from scanning electron microscopy (SEM) and reference crystalline volume fraction values estimated with Raman spectroscopy, respectively. The maximum relative difference in thickness values obtained from reflectance spectra and SEM measurements is only 3%. Moreover, the maximum relative difference in crystalline volume fractions derived from reflectance and Raman spectra is just 1.8%.

Through machine learning (ML), the measurement range of a 1-D CMOS-MEMS anemometer has been extended by a factor of 8.3, while enabling 360(degrees) directional measurement. Without the use of ML, the angle of attack of the flow was inseparable from the wind speed using the sensor output due to its dependence on both parameters simultaneously. Random forest and gradient boosting ML algorithms have been evaluated for their performance. The random forest regression performed best in all tests, extending the sensor's measurement range from 1.2 to 10 m/s for all directions, with a 3.9% full-scale error for speed and 5% for direction. Gradient boosting performed slightly worse (4.3% and 6.6%) but did have much smaller model sizes (<1%). A Shapley additive explanation analysis was performed to determine the impact of different sensor outputs on the ML prediction, giving key insights into ways to improve sensor designs. Despite the implicit symmetry of a 1-D sensor's output for positive and negative wind angles, the ML models can extract small (hidden) features from the data, which contain information on the direction. The 1-D configuration in combination with ML allows for a state-of-the-art accuracy in both speed and direction, with a significantly smaller sensor footprint (0.245 mm(2)).

In this paper, we present an inline characterization technique to determine spatially resolved thickness maps of ultra-thin layers on textured silicon substrates. The technique is based on multispectral imaging and optical modelling of discrete spectral reflectance data using rigorous polarization ray tracing and the transfer matrix method. The study demonstrates that quantitative inspection of ultra-thin amorphous silicon (a-Si) layers on textured silicon substrates requires an extension of the standard RGB illumination by two additional LED wavelengths in the near-UV. As the required five images are measured in less than a second, the tool is a suitable candidate for inline applications. The optical modelling requires reflectance-calibrated images which are obtained via linear calibration functions and allows the a-Si thickness to be determined at each pixel. The thin-film thickness can be determined either by a direct modelling of the measured reflectance spectra or by a differential approach using the reflectance spectra before and after coating to eliminate effects from non-idealities due to scattering as well as instrumental errors. The a-Si thickness extracted from the reflection data at the five chosen LED wavelengths shows good quantitative agreement with reference values from spectrally-resolved differential reflectance data. Evaluating a test sample with an intentional a-Si thickness variation, we compared the results from the multispectral thickness map and reference values from spectroscopic ellipsometry. We found good quantitative agreement for a-Si thicknesses above 10 nm and a slight overestimation of about 1.5 nm for thinner layers. Overall, the multispectral approach based on only five different channels proves to allow quantitative thickness maps with reasonable accuracy at inline speed.

The Belle II experiment at the SuperKEKB $e^{+}e^{-}$ collider took data from 2019 to 2022 (Run 1) and is currently undergoing its planned first long shutdown (LS1). During its operational period, SuperKEKB achieved a record-breaking instantaneous luminosity of 4.7 x 10$^{34}$ cm$^{-2}$s$^{-1}$ [1] and Belle II recorded a dataset corresponding to 428 fb$^{-1}$. The Belle II Pixel Vertex Detector (PXD), which is the innermost sub-detector, is based on the DEpleted P-channel Field Effect Transistor (DEPFET) technology [2]. Along with the Silicon Vertex Detector (SVD) [3], utilizing double-sided silicon strips, this forms the Belle II Vertex Detector system (VXD), enabling precise reconstruction of primary and decay vertices. The PXD module features a 75 $\mu$m-thin DEPFET sensor area with varying pixel sizes from 50 x 55 $\mu$m to 50 x 85 $\mu$m while maintaining a hit efficiency of about 99 %. Its average material budget inside the physics acceptance corresponds to 0.2 % X$_{0}$ per layer. PXD consist of 20 ladders arranged in two cylindrical layers around the beam axis. The Run 1 PXD was installed in a reduced configuration comprising the full inner layer (L1, eight ladders) and only two out of twelve outer layer (L2) ladders. In this article, we will illuminate the performance and operational challenges observed during its 4-year operation in a harsh environment characterized by a high beam background level. A fully populated detector can compensate acceptance losses by redundancy and reduce the probability of wrong hit assignment introduced by higher background levels resulting from increased instantaneous luminosity. During LS1 PXD was replaced by a new, fully populated PXD2. Its commissioning and testing phase during LS1 will be described. A hit efficiency of $>$98 % was measured in most regions using cosmic particles. The current installation schedule foresees beam operation to resume in winter 23/24.

The Belle II experiment at the SuperKEKB collider in Tsukuba, Japan, has collected e+e- + e - collision data between 2019 and 2022. After reaching a record-breaking instantaneous luminosity of 4.71x1034 . 71x10 34 cm -2 s -1 and recording a dataset corresponding to 424 fb -1 , it completed its first planned long shutdown phase in December 2023. Aside from upgrades of the collider and detector maintenance, the shutdown was used for the installation of the two-layer Pixel VerteX Detector (PXD). As the innermost sub-detector, multiple scattering effects need to be reduced. PXD utilizes the Depleted P-channel Field Effect Transistor (DEPFET) technology, allowing for a material budget of 0.21% X0 0 per layer. Each of the tracker's 40 modules consists of an array of 250x768 pixels with a pitch ranging from 50 mu mx 55 mu m for the inner to 85 mu mx 55 mu m for the outer layer yielding high gain and high signal-to-noise ratio while retaining about 99% hit efficiency. This article discusses the experience of the 4-year operation of the previous single-layer PXD in harsh background conditions as well as commissioning and testing of the fully-populated PXD2 during Long Shutdown 1.

A post‐mortem analysis is conducted after potential‐induced degradation (PID) of a commercial copper‐indium‐gallium‐selenide (CIGS) photovoltaic module. After PID, the conversion efficiency of the total module decreased by 62%. Electroluminescence images of the module show that the edges of the modules were much more affected by the PID than the middle part of the module. Coring samples were prepared of the different areas and chemical compositional information of the various areas was combined with electrical characterisation, cell modelling and luminescence data to obtain an overall perspective on the root cause of degradation in these modules during high voltage stress. Consistent with earlier studies on cell level, the module analysis shows the occurrence of alkali migration. From current–voltage modelling, it was concluded that the degradation of the most affected areas is due to an increase in bulk and CdS/CIGS interface defects, likely induced by ion migration. Further degradation on the same samples occurred when they are taken out of the argon‐filled glovebox and stored under ambient conditions. Remarkably, the PID‐degraded areas show stronger degradation when left in ambient atmosphere, as well as a stronger Na redistribution. These new results show that ion migration not only causes the immediate degradation but also strongly affects the longer‐term stability of the cells in ambient atmosphere. This indicates that PID degradation makes CIGS devices more vulnerable to hermeticity problems, which are most prominent at the module edges.

This paper presents the main results of COST Action PEARL PV, aiming at finding connections between the observed performance of monitored PV systems and degradation causes and failure modes according to literature with a focus on the most dominant technology among installed PV modules, namely silicon PV. It is found that there there exists a great potential for performance improvements, though in practice it is difficult to identify exact causes for failure and underperformance.

We present the analysis and measurement results of photodiodes (PDs) fabricated in 22 nm Fully-Depleted Silicon-On-Insulator (FDSOI) technology at a wavelength of 850 nm. To the best of our knowledge this is the first paper to give detailed information about PDs in 22 nm FDSOI. FDSOI has the unique opportunity to place a PD in SOI, which is potentially very fast, on top of bulk devices such as PNP-transistors for temperature sensors. Its measured responsivity is 4 μA/W at a bandwidth (BW) of 3.4 GHz. Several bulk PDs, including PW/NW/DNW, PW/DNW/PSUB, and NW/PSUB have also been characterised. They have responsivities between 6 mA/W and 207 mA/W and BWs between 23 MHz and 5.8 GHz. 22 nm FDSOI shows potential for fully-integrated high-speed optical receivers, as it combines ∼90 nm bulk CMOS PD performance with 22 nm RF and digital processing capabilities on a single die.

Carbon black doped polymer filaments for Fused Filament Fabrication (FFF) have previously been shown to exhibit temperature dependent resistance. In this work three commercially available filaments were characterized by thermal treatment and exposure, whilst monitoring their electrical resistance. Temperature coefficients of resistance were determined for the materials, along with the influence of printing orientation.

We report a search for lepton-flavor-violating decays $\tau^- \to \ell^- \phi$ ($\ell^- =e^-,\mu^-$) at the Belle II experiment, using a sample of electron-positron data produced at the SuperKEKB collider in 2019-2021 and corresponding to an integrated luminosity of 190 fb$^{-1}$. We use a new untagged selection for $e^+e^- \to \tau^+\tau^-$ events, where the signal $\tau$ is searched for as a neutrinoless final state of a single charged lepton and a $\phi$ meson and the other $\tau$ is not reconstructed in any specific decay mode, in contrast to previous measurements by the BaBar and Belle experiments. We find no evidence for $\tau^- \to \ell^- \phi$ decays and obtain upper limits on the branching fractions at 90% confidence level of 23 $\times 10^{-8}$ and 9.7$\times 10^{-8}$ for $\tau^- \rightarrow e^-\phi$ and $\tau^- \rightarrow \mu^-\phi$, respectively

We present a measurement of the branching fractions of four $B^{0,-}\to D^{(*)+,0} K^- K^{0}_S$ decay modes. The measurement is based on data from SuperKEKB electron-positron collisions at the $\Upsilon(4S)$ resonance collected with the Belle II detector and corresponding to an integrated luminosity of ${362~\text{fb}^{-1}}$. The event yields are extracted from fits to the distributions of the difference between expected and observed $B$ meson energy to separate signal and background, and are efficiency-corrected as a function of the invariant mass of the $K^-K_S^0$ system. We find the branching fractions to be: \[ \text{B}(B^-\to D^0K^-K_S^0)=(1.89\pm 0.16\pm 0.10)\times 10^{-4}, \] \[ \text{B}(\overline B{}^0\to D^+K^-K_S^0)=(0.85\pm 0.11\pm 0.05)\times 10^{-4},\] \[ \text{B}(B^-\to D^{*0}K^-K_S^0)=(1.57\pm 0.27\pm 0.12)\times 10^{-4}, \] \[ \text{B}(\overline B{}^0\to D^{*+}K^-K_S^0)=(0.96\pm 0.18\pm 0.06)\times 10^{-4},\] where the first uncertainty is statistical and the second systematic. These results include the first observation of $\overline B{}^0\to D^+K^-K_S^0$, $B^-\to D^{*0}K^-K_S^0$, and $\overline B{}^0\to D^{*+}K^-K_S^0$ decays and a significant improvement in the precision of $\text{B}(B^-\to D^0K^-K_S^0)$ compared to previous measurements.

The degradation of photovoltaic (PV) systems is one of the key factors to address in order to reduce the cost of the electricity produced by increasing the operational lifetime of PV systems. To reduce the degradation, it is imperative to know the degradation and failure phenomena. This review article has been prepared to present an overview of the state-of-the-art knowledge on the reliability of PV modules. Whilst the most common technology today is mono- and multi-crystalline silicon, this article aims to give a generic summary which is relevant for a wider range of photovoltaic technologies including cadmium telluride, copper indium gallium selenide and emerging low-cost high-efficiency technologies. The review consists of three parts: firstly, a brief contextual summary about reliability metrics and how reliability is measured. Secondly, a summary of the main stress factors and how they influence module degradation. Finally, a detailed review of degradation and failure modes, which has been partitioned by the individual component within a PV module. This section connects the degradation phenomena and failure modes to the module component, and its effects on the PV system. Building on this knowledge, strategies to improve the operational lifetime of PV systems and thus, to reduce the electricity cost can be devised. Through extensive testing and failure analysis, researchers now have a much better overview of stressors and their impact on long term stability.

We present results on the semileptonic decays $B^0 \to \rho^- \ell^+ \nu_\ell$ and $B^+ \to \rho^0 \ell^+ \nu_\ell$ in a sample corresponding to 189.9/fb of Belle II data at the SuperKEKB $e^- e^+$ collider. Signal decays are identified using full reconstruction of the recoil $B$ meson in hadronic final states. We determine the total branching fractions via fits to the distributions of the square of the "missing" mass in the event and the dipion mass in the signal candidate and find ${\mathcal{B}(B^0\to\rho^-\ell^+ \nu_\ell) = (4.12 \pm 0.64(\mathrm{stat}) \pm 1.16(\mathrm{syst})) \times 10^{-4}}$ and ${\mathcal{B}({B^+\to\rho^0\ell^+\nu_\ell}) = (1.77 \pm 0.23 (\mathrm{stat}) \pm 0.36 (\mathrm{syst})) \times 10^{-4}}$ where the dominant systematic uncertainty comes from modeling the nonresonant $B\to (\pi\pi)\ell^+\nu_\ell$ contribution.

Recently, the Cox-Strack method for contact resistivity determination is increasingly used in the context of photovoltaic cell engineering. This document reviews the literature published in the period 2017-2021 containing Cox-Strack measurement results. As the Cox-Strack method is error-prone, we analyze this literature on the possible inaccuracies that may arise due to (1) approximations by Cox and Strack, (2) the choice of contact diameters, and (3) resistive coatings. On the basis of our findings, more than half of the 93 reviewed articles may need additional analysis for an accurate quantification of the lower reported contact resistance values. The article concludes with recommendations for an improved Cox-Strack methodology.

The Belle II experiment at the SuperKEKB accelerator has started its physics data taking with the full detector setup in March 2019. It aims to collect 40 times more e+e- collision data compared with its predecessor Belle experiment. The Belle II pixel detector (PXD) is based on the Depleted P-channel Field Effect Transistor (DEPFET) technology. The PXD plays an important role in the tracking and vertexing of the Belle II detector. Its two layers are arranged at radii of 14 mm and 22 mm around the interaction point. The sensors are thinned down to 75 mu m to minimize multiple scattering, and each module has interconnects and ASICs integrated on the sensor with silicon frames for mechanical support. PXD showed good performance during data taking. It also faces several operational challenges due to the high background level from the SuperKEKB accelerator, such as the damage from beam loss events, the drift in the HV working point due to radiation effect, and the impact of the high background.

AbstractA comprehensive understanding of failure modes of solar photovoltaic (PV) modules is key to extending their operational lifetime in the field. In this review, first, specific failure modes associated with mature PV technologies, such as crystalline silicon (c‐Si), copper indium gallium selenide (CIGS) and cadmium telluride (CdTe), are framed by sources of specific failure modes, their development from the early‐developmental stages onwards and their impact upon long term performance of PV modules. These failure modes are sorted by both PV technology and location of occurrence in PV modules, such as substrate, encapsulant, front and rear electrode, absorber and interlayers. The second part of the review is focused on emerging PV technologies, such as perovskites solar cells, dye sensitised and organic PVs, where due to their low to medium technology readiness levels, specific long‐term degradation mechanisms have not fully emerged, and most mechanisms are only partially understood. However, an in‐depth summary of the known stability challenges associated with each emerging PV technology is presented. Finally, in this paper, lessons learned from mature PV technologies are reviewed, and considerations are given in to how these might be applied to the further development of emerging technologies. Namely, any emerging PV technology must eventually pass industry‐standard qualification tests, while warranties for the lifetime of modern c‐Si‐based modules might be extended beyond the existing warranted life of 25 years.