Applied Physics
New submissions
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New submissions for Fri, 10 May 24
- [1] arXiv:2405.05346 [pdf, other]
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Title: Data-Driven Cooling Tower Optimization: A Comprehensive Analysis of Energy Savings using Microsand FiltrationSubjects: Applied Physics (physics.app-ph)
Effective management of cooling tower systems requires thorough disinfection. While traditional chemical water treatment methods are currently the most prominent strategy, they are costly and yield limited results when relied upon as the sole approach. Cross-flow microsand filtration systems offer a promising alternative with the added benefit of potentially increasing evaporative cooling efficiency, thus saving energy. A comprehensive data-driven analysis over two cooling seasons evaluated the energetic performance of a system equipped with and without an operating filter. For similar environmental conditions, the coefficient of performance was on average 18% higher and was higher 63% of the time when the filter was operating, indicating superior heat transfer efficiency and significant energy savings. It was also 41% higher during periods of high cooling demand. Consequently, the filter and the system work more efficiently at high wet-bulb temperature and thermal load. Machine learning modeling suggested that operating the filter year-round could save between 5% and 13% of the energy bill, primarily during the cooling season. Continuous filter operation is essential as it mitigates biofouling, underscoring its long-term significance, even during periods of lower thermal loads. Integrating filtration systems into cooling tower management therefore fosters sustainable practices by decreasing energy consumption and biofouling.
- [2] arXiv:2405.05401 [pdf, other]
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Title: Imaging Hot Photocarrier Transfer across a Semiconductor Heterojunction with Ultrafast Electron MicroscopyAuthors: Basamat S. Shaheen, Kenny Huynh, Yujie Quan, Usama Choudhry, Ryan Gnabasik, Zeyu Xiang, Mark Goorsky, Bolin LiaoSubjects: Applied Physics (physics.app-ph)
Semiconductor heterojunctions have gained significant attention for efficient optoelectronic devices owing to their unique interfaces and synergistic effects. Interaction between charge carriers with the heterojunction plays a crucial role in determining device performance, while its spatial-temporal mapping remains lacking. In this study, we employ scanning ultrafast electron microscopy (SUEM), an emerging technique that combines high spatial-temporal resolution and surface sensitivity, to investigate photocarrier dynamics across a Si/Ge heterojunction. Charge dynamics are selectively examined across the junction and compared to far bulk areas, through which the impact of the built-in potential, band offsets, and surface effects is directly visualized. In particular, we find that the heterojunction drastically modifies the hot photocarrier diffusivities by up to 300%. These findings are further elucidated with insights from the band structure and surface potential measured by complementary techniques. This work demonstrates the tremendous effect of heterointerfaces on charge dynamics and showcases the potential of SUEM in characterizing realistic devices.
- [3] arXiv:2405.05432 [pdf, ps, other]
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Title: 2D ferroelectrics and ferroelectrics with 2D: materials and device prospectsComments: 46 pages, 7 figuresSubjects: Applied Physics (physics.app-ph); Materials Science (cond-mat.mtrl-sci)
Ferroelectric and two-dimensional materials are both heavily investigated classes of electronic materials. This is unsurprising since they both have superlative fundamental properties and high-value applications in computing, sensing etc. In this Perspective, we investigate the research topics where 2D semiconductors and ferroelectric materials both in 2D or 3D form come together. 2D semiconductors have unique attributes due to their van der Waals nature that permits their facile integration with any other electronic or optical materials. In addition, the emergence of ferroelectricity in 2D monolayers, multilayers, and artificial structures offers further advantages since traditionally ferroelectricity has been difficult to achieve in extremely thickness scaled materials. In this perspective, we elaborate on the applications of 2D materials + ferroelectricity in non-volatile memory devices highlighting their potential for in-memory computing, neuromorphic computing, optoelectronics, and spintronics. We also suggest the challenges posed by both ferroelectrics and 2D materials, including material/device preparation, and reliable characterizations to drive further investigations at the interface of these important classes of electronic materials.
- [4] arXiv:2405.05454 [pdf, other]
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Title: Molecular dynamics characterization of the interfacial structure and forces of the methane-ethane sII gas hydrate interfaceComments: 17 pages, 7 figures, 1 tableSubjects: Applied Physics (physics.app-ph)
The nucleation of gas hydrates is of great interest in flow assurance, global energy demand, and carbon capture and storage. A complex molecular understanding is critical to control hydrate nucleation and growth in the context of potential applications. Molecular dynamics is employed in this work combined with the mechanical definition of surface tension to assess the surface stresses that control some of the behavior at the interface. Ensuring careful sampling and simulation behavior, this work extracts meaningful results from molecular properties. We characterize the interfacial tension for sII methane/ethane hydrate and gas mixtures for different temperatures and pressures. We find that the surface tension trends positively with temperature in a balance of water-solid and water-gas interactions. The molecular dipole shows the complexities of water molecule behavior in small, compressed pre-melting layer that emerges as a quasi-liquid. These behaviors contribute to the developing knowledge base surrounding practical applications of this interface.
- [5] arXiv:2405.05491 [pdf, other]
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Title: Atomic layer etching of SiO$_2$ using sequential exposures of Al(CH$_3$)$_3$ and H$_2$/SF$_6$ plasmaComments: 19 pages, 8 figures, 1 tableSubjects: Applied Physics (physics.app-ph); Materials Science (cond-mat.mtrl-sci)
On-chip photonic devices based on SiO$_2$ are of interest for applications such as microresonator gyroscopes and microwave sources. Although SiO$_2$ microdisk resonators have achieved quality factors exceeding one billion, this value remains an order of magnitude less than the intrinsic limit due to surface roughness scattering. Atomic layer etching (ALE) has potential to mitigate this scattering because of its ability to smooth surfaces to sub-nanometer length scales. While isotropic ALE processes for SiO$_2$ have been reported, they are not generally compatible with commercial reactors, and the effect on surface roughness has not been studied. Here, we report an ALE process for SiO$_2$ using sequential exposures of Al(CH$_3$)$_3$ (trimethylaluminum, TMA) and Ar/H$_2$/SF$_6$ plasma. We find that each process step is self-limiting, and that the overall process exhibits a synergy of 100%. We observe etch rates up to 0.58 \r{A} per cycle for thermally-grown SiO$_2$ and higher rates for ALD, PECVD, and sputtered SiO$_2$ up to 2.38 \r{A} per cycle. Furthermore, we observe a decrease in surface roughness by 62% on a roughened film. The residual concentration of Al and F is around 1-2%, which can be further decreased by O$_2$ plasma treatment. This process could find applications in smoothing of SiO$_2$ optical devices and thereby enabling device quality factors to approach limits set by intrinsic dissipation.
- [6] arXiv:2405.05632 [pdf, ps, other]
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Title: Controlled Fabrication of Native Ultra-Thin Amorphous Gallium Oxide from 2D Gallium Sulfide for Emerging Electronic ApplicationsAuthors: AbdulAziz AlMutairi, Aferdita Xhameni, Xuyun Guo, Irina Chircă, Valeria Nicolosi, Stephan Hofmann, Antonio LombardoSubjects: Applied Physics (physics.app-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Oxidation of two-dimensional (2D) layered materials has proven advantageous in creating oxide/2D material heterostructures, opening the door for a new paradigm of low-power electronic devices. Gallium (II) sulfide ($\beta$-GaS), a hexagonal phase group III monochalcogenide, is a wide bandgap semiconductor with a bandgap exceeding 3 eV in single and few layer form. Its oxide, gallium oxide (Ga$_2$O$_3$), combines large bandgap (4.4-5.3 eV) with high dielectric constant (~10). Despite the technological potential of both materials, controlled oxidation of atomically-thin $\beta$-GaS remains under-explored. This study focuses into the controlled oxidation of $\beta$-GaS using oxygen plasma treatment, achieving ultrathin native oxide (GaS$_x$O$_y$, ~4 nm) and GaS$_x$O$_y$/GaS heterostructures where the GaS layer beneath remains intact. By integrating such structures between metal electrodes and applying electric stresses as voltage ramps or pulses, we investigate their use for resistive random-access memory (ReRAM). The ultrathin nature of the produced oxide enables low operation power with energy use as low as 0.22 nJ per operation while maintaining endurance and retention of 350 cycles and 10$^4$ s, respectively. These results show the significant potential of the oxidation-based GaS$_x$O$_y$/GaS heterostructure for electronic applications and, in particular, low-power memory devices.
- [7] arXiv:2405.05693 [pdf, ps, other]
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Title: Development and optimization of large-scale integration of 2D material in memristorsAuthors: Clotilde Ligaud, Lucie Le Van-Jodin, Bruno Reig, Pierre Trousset, Paul Brunet, Michaël Bertucchi, Clémence Hellion, Nicolas Gauthier, Le Van-Hoan, Hanako Okuno, Djordje Dosenovic, Stéphane Cadot, Remy Gassilloud, Matthieu JametComments: 11 pages, 6 figuresSubjects: Applied Physics (physics.app-ph); Materials Science (cond-mat.mtrl-sci)
Two-dimensional (2D) materials like transition metal dichalcogenides (TMD) have proved to be serious candidates to replace silicon in several technologies with enhanced performances. In this respect, the two remaining challenges are the wafer scale growth of TMDs and their integration into operational devices using clean room compatible processes. In this work, two different CMOS-compatible protocols are developed for the fabrication of MoS$_2$-based memristors, and the resulting performances are compared. The quality of MoS$_2$ at each stage of the process is characterized by Raman spectroscopy and x-ray photoemission spectroscopy. In the first protocol, the structure of MoS$_2$ is preserved during transfer and patterning processes. However, a polymer layer with a minimum thickness of 3 nm remains at the surface of MoS$_2$ limiting the electrical switching performances. In the second protocol, the contamination layer is completely removed resulting in improved electrical switching performances and reproducibility. Based on physico-chemical and electrical results, the switching mechanism is discussed in terms of conduction through grain boundaries.
Cross-lists for Fri, 10 May 24
- [8] arXiv:2405.05399 (cross-list from eess.SY) [pdf, ps, other]
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Title: 3-way equal filtering power divider using compact folded-arms square open-Loop resonatorComments: 5 pages, 5 figures, 1 tableSubjects: Systems and Control (eess.SY); Applied Physics (physics.app-ph)
Microstrip three-way (that is, 4.8 dB) integrated filtering power divider (FPD) is presented in this paper. The proposed FPD evenly distributes an input power signal into three equal output signals. The design incorporates balanced signal power division, and filtering technology for the removal of unwanted frequency elements and aimed at enhancing signal quality and efficiency in the radiofrequency (RF) front-end of communication systems. Microstrip folded-arms square open-loop resonator (FASOLR) is employed in the design implementation to achieve compact size. The proposed FPD features a 2.6 GHz centre frequency, with a 0.03 fractional bandwidth. The implementation is carried out on Rogers RT/Duroid 6010LM substrate with a dielectric constant of 10.7, a thickness of 1.27 mm and a loss tangent of 0.0023. The good agreement between the theoretical and practical results verifies the effectiveness of the FPD in delivering equal power outputs at the three output ports, and at the same time filtering out unwanted frequencies. The practical results of the prototype FPD indicate a good return loss of better than 15.5 dB and an insertion loss of better than 4.77+0.34 dB. The design prototype achieved compact size of 0.31 {\lambda}g x 0.18 {\lambda}g. {\lambda}g is the guided wavelength for the microstrip line impedance at the centre frequency of the 3-way equal filtering power divider.
- [9] arXiv:2405.05716 (cross-list from physics.optics) [pdf, ps, other]
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Title: Bimodal Plasmonic Refractive Index Sensors Based on SU-8 WaveguidesAuthors: Omkar Bhalerao, Stephan Suckow, Horst Windgassen, Harry Biller, Konstantinos Fotiadis, Stelios Simos, Evangelia Chatzianagnostou, Dimosthenis Spasopoulos, Pratyusha Das, Laurent Markey, Jean-Claude Weeber, Nikos Pleros, Matthias Schirmer, Max C. LemmeComments: 30 pagesSubjects: Optics (physics.optics); Applied Physics (physics.app-ph)
Plasmonic refractive index sensors are essential for detecting subtle variations in the ambient environment through surface plasmon interactions. Current efforts utilizing CMOS-compatible, plasmo-photonic Mach-Zehnder interferometers with active power balancing exhibit high sensitivities at the cost of fabrication and measurement complexity. Alternatively, passive bimodal plasmonic interferometers based on SU-8 waveguides present a cost-effective solution with a smaller device footprint, though they currently lack opto-mechanical isolation due to exposed photonic waveguides. In this work, we introduce innovative polymer-core and polymer-cladded bimodal plasmonic refractive index sensors with high refractive index contrast. Our sensors feature an aluminum stripe, a bilayer SU-8 photonic waveguide core, and the experimental optical cladding polymer SX AR LWL 2.0. They achieve a sensitivity of (6300 $\pm$ 460) nm/RIU (refractive index unit), surpassing both traditional and polymer-based plasmo-photonic sensors. This approach enables integrated, wafer-scale, CMOS-compatible, and low-cost sensors and facilitates plasmonic refractive index sensing platforms for various applications.
Replacements for Fri, 10 May 24
- [10] arXiv:2405.03818 (replaced) [pdf, other]
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Title: AniMAIRE - A New Openly Available Tool for Calculating Atmospheric Ionising Radiation Dose Rates and Single Event Effects During Anisotropic ConditionsComments: 22 pages, 7 figures, manuscript submitted to Space Weather Journal. The previous version of this had the incorrect abstract and title, this has been fixed in this versionSubjects: Applied Physics (physics.app-ph); Computational Physics (physics.comp-ph); Space Physics (physics.space-ph)
- [11] arXiv:2310.06049 (replaced) [pdf, other]
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Title: Quantum Illumination and Quantum Radar: A Brief OverviewSubjects: Quantum Physics (quant-ph); Applied Physics (physics.app-ph); Data Analysis, Statistics and Probability (physics.data-an); Instrumentation and Detectors (physics.ins-det); Optics (physics.optics)
- [12] arXiv:2401.10701 (replaced) [pdf, ps, other]
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Title: Physics to System-level Modeling of Silicon-organic-hybrid Nanophotonic DevicesComments: 15 pages, 7 figures,Subjects: Optics (physics.optics); Applied Physics (physics.app-ph)
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