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Device simulation of Cu(In,Ga)Se2 solar cells by means of voltage dependent admittance spectroscopy
摘要： The simulation of solar cell devices is important for the understanding of defect physics and loss mechanisms in real solar cells. On the other hand, voltage dependent admittance spectroscopy delivers essential information for establishing a baseline simulation model of Cu(In,Ga)Se2 (CIGSe) solar cells. Here we give an explanation for the weak temperature dependence of the N1-signal, the latter being not compatible with a bulk defect or with a simple hole barrier at the Mo back contact. Furthermore, we find a Ed,IF – EV ≈ 0.3 eV deep recombination-active acceptor state at the absorber/buffer interface made of air-light exposed CIGSe absorbers. This gives us the ability to explain the reduction of power conversion efficiency of solar cells made from air-light exposed absorbers. From the voltage dependent capacitance step of this interface defect we can deduce the formerly unknown position of the Fermi level at the hetero junction in equilibrium which is close to mid-gap. Simulation of dark J-V curves allows a refinement of the parameter of this absorber/buffer interface defect, resulting in a defect density of Nd,IF ≈ 3.5·1011 cm-2 as well as capture cross sections of σn ≈ 4·10-16 cm2 for electrons and σp ≈ 3·10-11 cm2 for holes.
关键词： device simulation,Cu(In,Ga)Se2,admittance spectroscopy,defect physics,solar cells
更新于2025-11-14 17:28:48
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Microscopic Control and Detection of Ultracold Strontium in Optical-Tweezer Arrays
摘要： Optical tweezers provide a versatile platform for the manipulation and detection of single atoms. Here, we use optical tweezers to demonstrate a set of tools for the microscopic control of atomic strontium, which has two valence electrons. Compared to the single-valence-electron atoms typically used with tweezers, strontium has a more complex internal state structure with a variety of transition wavelengths and linewidths. We report single-atom loading into an array of subwavelength scale optical tweezers and light-shift-free control of a narrow-linewidth optical transition. We use this transition to perform three-dimensional ground-state cooling and to enable high-fidelity nondestructive imaging of single atoms on subwavelength spatial scales. These capabilities, combined with the rich internal structure of strontium, open new possibilities including tweezer-based metrology, new quantum computing architectures, and new paths to low-entropy many-body physics.
关键词： Quantum Information,Atomic and Molecular Physics,Quantum Physics
更新于2025-09-23 15:23:52
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Alkaline-Earth Atoms in Optical Tweezers
摘要： We demonstrate single-shot imaging and narrow-line cooling of individual alkaline-earth atoms in optical tweezers; specifically, strontium trapped in 515.2-nm light. Our approach enables high-fidelity detection of single atoms by imaging photons from the broad singlet transition while cooling on the narrow intercombination line, and we extend this technique to highly uniform two-dimensional tweezer arrays with 121 sites. Cooling during imaging is based on a previously unobserved narrow-line Sisyphus mechanism, which we predict to be applicable in a wide variety of experimental situations. Further, we demonstrate optically resolved sideband cooling of a single atom to near the motional ground state of a tweezer, which is tuned to a magic-trapping configuration achieved by elliptical polarization. Finally, we present calculations, in agreement with our experimental results, that predict a linear-polarization and polarization-independent magic crossing at 520(2) nm and 500.65(50) nm, respectively. Our results pave the way for a wide range of novel experimental avenues based on individually controlled alkaline-earth atoms in tweezers—from fundamental experiments in atomic physics to quantum computing, simulation, and metrology.
关键词： Quantum Information,Atomic and Molecular Physics,Quantum Physics
更新于2025-09-23 15:23:52
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High-Efficiency Measurement of an Artificial Atom Embedded in a Parametric Amplifier
摘要： A crucial limit to measurement efficiencies of superconducting circuits comes from losses involved when coupling to an external quantum amplifier. Here, we realize a device circumventing this problem by directly embedding an artificial atom, comprised of a transmon qubit, within a flux-pumped Josephson parametric amplifier. This configuration is able to enhance dispersive measurement without exposing the qubit to appreciable excess backaction. Near-optimal backaction is obtained by engineering the circuit to permit high-power operation that reduces information loss to unmonitored channels associated with the amplification and squeezing of quantum noise. By mitigating the effects of off-chip losses downstream, the on-chip gain of this device produces end-to-end measurement efficiencies of up to 80%. Our theoretical model accurately describes the observed interplay of gain and measurement backaction and delineates the parameter space for future improvement. The device is compatible with standard fabrication and measurement techniques and, thus, provides a route for definitive investigations of fundamental quantum effects and quantum control protocols.
关键词： Quantum Information,Condensed Matter Physics,Quantum Physics
更新于2025-09-23 15:23:52
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Globo de plasma: uma montagem simples com amplo potencial para discuss?es em sala de aula
摘要： Given the importance and necessity of integration of Modern and Contemporary Physics in High School curriculum, this article shows how to make an alternative plasma globe with easily acquired materials, that can be easily reproduced by teachers and students. The apparatus has the potential to support discussions guided by structuring themes proposed in Brazilian official documents, in a contextualized way, which shows the relationship between the phenomenon, the natural world and technological applications present in the daily lives of students.
关键词： Plasma globe. Contemporary Physics teaching.
更新于2025-09-23 15:23:52
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Mechanism Behind the Easy Exfoliation of Ga <sub/>2</sub> O <sub/>3</sub> Ultra-Thin Film Along (100) Surface
摘要： The transparent wide band gap semiconductor β-Ga2O3 has gained wide attention due to its suitability to a wide range of applications. Despite not being a van der Waals material and having highly strong ionic bonding, the material can be mechanically cleaved and exfoliated easily along favorable surfaces to make ultra-thin layers and used in device fabrications. One of the interesting properties of this material is that thin layers preserve the pristine bulk-like electronic properties, which makes it even more promising for applications in power devices. However, very little is known about the mechanism why such ultra-thin film or even single bilayer exfoliation is favorable from the bulk. In this letter, we have explained the mechanism of such phenomenon by detailed analyses of different types of Ga–O bonding character. The protocol of methodology used and developed in this study can be utilized in general to understand bond breaking and forming of other complex materials as well. This understanding will give us a better control to fabricate thin film 2D devices.
关键词： density functional theory,bond energy,computational physics,2D Ga2O3,easy exfoliation,surface energy
更新于2025-09-23 15:23:52
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Experimental studies and mathematical simulation of intermittent infrared and convective drying of sweet potato (Ipomoea batatas L.)
摘要： Intermittent infrared and convective drying (IIRCD) is a novel drying method that can enhance energy efficiency and quality of dried product. The mechanism of drying using this method is not yet fully understood. Mathematical models that describe the drying process of IIRCD for agricultural crops do not exist. In this study, a physics based mathematical model was developed to understand the mechanism of drying sweet potato using IIRCD. The model was based on shrinkage dependent diffusivity and evaporation phenomenon. COMSOL Multiphysics finite element software was employed for the model simulation. The simulation results of moisture and temperature distribution were validated by experimental drying data. The results fitted closely with experimental data. Drying of sweet potato using IIRCD was found to be more efficient in terms of final product quality compared to convective hot-air drying method.
关键词： quality of dried products,COMSOL,Physics-based model,modelling and simulation
更新于2025-09-23 15:23:52
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Processing a New Hyperspectral Data Set for Target Detection and Atmospheric Compensation Algorithm Assessment: The RIT2017 Data Set
摘要： This paper introduces a new and challenging hyperspectral dataset to the remote sensing community called the 'RIT2017 Data Set' which can be used for the assessment of target detection algorithms. This dataset encompasses 90 targets in a background of up to 8 million pixels (or less if sub-setting). The same dataset can also be used for atmospheric compensation studies for it has identical sets of large panels in both the sun and full shadow. This paper briefly introduces the data collection campaign, the target objects, and addresses the radiometric fidelity of the imaging spectrometer data, which showed very good results. Lastly, the data is atmospherically compensated using an in-scene technique, which also showed fairly good results.
关键词： atmospheric compensation,physics-based modeling,hyperspectral imaging,target detection,radiative transfer
更新于2025-09-23 15:23:52
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Characterisation of Timepix3 with 3D sensor
摘要： Tests were performed at the SPS facilities at CERN using a 40 GeV/c pion beam with prototype 3D-Timepix3 detectors (3D detector). A planar-Timepix3 (planar detector) was placed along the beam axis together with the 3D detectors in a telescope arrangement for comparison and reference. We demonstrate that the combination of 3D-geometry silicon sensors and Timepix3 module can reduce the effect of charge sharing and lowers the carrier drift-time, while giving the same spectroscopy performance without sacrificing the timing or any performance advantages of the Timepix3 module.
关键词： Performance of High Energy Physics Detectors,databases),Detector control systems (detector and experiment monitoring and slow-control systems,hardware,algorithms,architecture
更新于2025-09-23 15:23:52
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The LXe calorimeter and the pixelated timing counter in the MEG II experiment
摘要： The MEG experiment is to look for a lepton flavor violating μ + → e+γ decay with an unprecedented sensitivity, and we set an upper limit of the branching ratio for this decay, 5.7 × 10?13 at 90% C.L. in 2013 which is a twenty times more stringent limit than the previous experiment, MEGA. Since the sensitivity improvement was limited by the accidental background, we have considered the major detector upgrade. A proposal was submitted to PSI committee, and was approved in 2013, which aims at a sensitivity enhancement of one order of magnitude compared with the current MEG experiment. Here mainly two components of the MEG detector will be introduced, a γ-ray calorimeter with 900 L of liquid xenon (LXe), and a pixelated timing counter. The LXe detector will be improved by increasing the granularity at the incident face, by replacing the current PMTs with a larger number of smaller photosensors (MPPC) and optimizing the photosensor layout also on the lateral faces. A new highly segmented, fast timing counter array will replace the old system to allow improved timing resolution capabilities.
关键词： visible and IR photons (solid-state),HPG,Large detector systems for particle and astroparticle physics,Photon detectors for UV,CZT,Gamma detectors (scintillators,HgI etc),Timing detectors
更新于2025-09-23 15:23:52