Pub Date : 2023-10-11DOI: 10.1088/1361-6463/acfe18
Songhao Wu, Zichun Liu, Han Yang, Yeliang Wang
Abstract As a simple and effective method for improving the crystalline quality of epitaxial Ga 2 O 3 film, post-thermal treatment has been identified as a competitive process involving crystal reconstruction accompanied by defect formation. In this study, β -Ga 2 O 3 films grown on a c-sapphire substrate using low-pressure chemical vapor deposition were subjected to thermal treatment at 1000 °C in air for various duration to investigate the effects of treatment time on the films. The full width at half maximum (FWHM) of x-ray rocking curves initially decreased from 1.62° to 0.98° with increasing treatment time up to 5 h, indicating improved crystallinity. This improvement is likely a result of the reduced angle between Ga 2 O 3 grains and the reconstructed Ga 2 O 3 lattice, oriented towards the (−201) plane due to the thermal treatment, as observed in the transmission electron microscope and electron back-scattering diffraction results. However, under 7 h of treatment, the crystallinity of Ga 2 O 3 degraded, as evidenced by an increased FWHM, as well as by x-ray photoelectron spectroscopy, photoluminescence, and time-of-flight secondary ion mass spectrometry results. This degradation can be attributed to the presence of massive oxygen vacancies and the substitutional incorporation of nitrogen into oxygen sites (N O ), resulting in defects.
{"title":"The effects of high temperature thermal treatments on β-Ga<sub>2</sub>O<sub>3</sub> films grown on c-sapphire by low-pressure CVD","authors":"Songhao Wu, Zichun Liu, Han Yang, Yeliang Wang","doi":"10.1088/1361-6463/acfe18","DOIUrl":"https://doi.org/10.1088/1361-6463/acfe18","url":null,"abstract":"Abstract As a simple and effective method for improving the crystalline quality of epitaxial Ga 2 O 3 film, post-thermal treatment has been identified as a competitive process involving crystal reconstruction accompanied by defect formation. In this study, β -Ga 2 O 3 films grown on a c-sapphire substrate using low-pressure chemical vapor deposition were subjected to thermal treatment at 1000 °C in air for various duration to investigate the effects of treatment time on the films. The full width at half maximum (FWHM) of x-ray rocking curves initially decreased from 1.62° to 0.98° with increasing treatment time up to 5 h, indicating improved crystallinity. This improvement is likely a result of the reduced angle between Ga 2 O 3 grains and the reconstructed Ga 2 O 3 lattice, oriented towards the (−201) plane due to the thermal treatment, as observed in the transmission electron microscope and electron back-scattering diffraction results. However, under 7 h of treatment, the crystallinity of Ga 2 O 3 degraded, as evidenced by an increased FWHM, as well as by x-ray photoelectron spectroscopy, photoluminescence, and time-of-flight secondary ion mass spectrometry results. This degradation can be attributed to the presence of massive oxygen vacancies and the substitutional incorporation of nitrogen into oxygen sites (N O ), resulting in defects.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136058101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-10DOI: 10.1088/1361-6463/acff05
rui Huang, Mingzhi Tang, Wanyu Kan, Hao Xu, Kai Wu, Zhiyong Wang, Hui Li
Abstract Lithium niobate (LiNbO 3 ) crystals are multifunctional materials with excellent performance and are widely used in integrated optical devices. In this study, 4-inch LiNbO 3 /Si and LiNbO 3 /SiO 2 /Si bonded pairs were obtained by optimizing Ar plasma activation. After pre-bonding was completed, a slicer was used to cut the LiNbO 3 /Si and LiNbO 3 /SiO 2 /Si pairs into 10 × 10 mm 2 squares, respectively. The optimal annealing temperature was determined through multiple annealing experiments. Scanning acoustic microscopy was used to confirm the high bonding rates of the two bonding pairs. Based on hydrophilic experiments and atomic force microscopy, the changes in the hydrophilicity and roughness of the LiNbO 3 , Si, and SiO 2 surfaces before and after activation can be compared. X-ray photoelectron spectroscopy was used to characterize the chemical structure composition of LiNbO 3 , Si, and SiO 2 surfaces. The dense interface without defects was observed by transmission electron microscopy. In addition, we explained the bonding mechanism between LiNbO 3 and Si-based materials. The reasons for the different bonding strengths of LiNbO 3 with Si and SiO 2 were also analyzed. Finally, the high bonding quality of LiNbO 3 and Si-based materials can meet the stringent material requirements of Si-based LiNbO 3 devices.
{"title":"Single-crystalline LiNbO3 integrated onto Si-based substrates via Ar plasma-activated low-temperature direct bonding","authors":"rui Huang, Mingzhi Tang, Wanyu Kan, Hao Xu, Kai Wu, Zhiyong Wang, Hui Li","doi":"10.1088/1361-6463/acff05","DOIUrl":"https://doi.org/10.1088/1361-6463/acff05","url":null,"abstract":"Abstract Lithium niobate (LiNbO 3 ) crystals are multifunctional materials with excellent performance and are widely used in integrated optical devices. In this study, 4-inch LiNbO 3 /Si and LiNbO 3 /SiO 2 /Si bonded pairs were obtained by optimizing Ar plasma activation. After pre-bonding was completed, a slicer was used to cut the LiNbO 3 /Si and LiNbO 3 /SiO 2 /Si pairs into 10 × 10 mm 2 squares, respectively. The optimal annealing temperature was determined through multiple annealing experiments. Scanning acoustic microscopy was used to confirm the high bonding rates of the two bonding pairs. Based on hydrophilic experiments and atomic force microscopy, the changes in the hydrophilicity and roughness of the LiNbO 3 , Si, and SiO 2 surfaces before and after activation can be compared. X-ray photoelectron spectroscopy was used to characterize the chemical structure composition of LiNbO 3 , Si, and SiO 2 surfaces. The dense interface without defects was observed by transmission electron microscopy. In addition, we explained the bonding mechanism between LiNbO 3 and Si-based materials. The reasons for the different bonding strengths of LiNbO 3 with Si and SiO 2 were also analyzed. Finally, the high bonding quality of LiNbO 3 and Si-based materials can meet the stringent material requirements of Si-based LiNbO 3 devices.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136255261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-10DOI: 10.1088/1361-6463/acfe1a
Guohui Zheng
Abstract Caged carbon clathrates may have profound applications in thermoelectrics due to their inherent host–guest relations. Using ab initio techniques, we investigate the electronic and phononic properties of type-VII C12 clathrate, which is a prototype of the widely studied ternary X –B–C clathrate, and tune its properties using lithium atom filling and boron atom substitution. Upon the introduction of pairwise B substition and a Li filler, the half-filled and fully filled structures retain their semiconducting characteristics due to balanced electron counts; however, their indirect band gaps are reduced. By comparing the phonon and thermal properties of filled and empty structures, we show that B substitution and Li fillers lift the phonon degeneracies, increase the three-phonon scattering phase spaces and eventually cause tenfold reductions in the relaxation time of phonons. The Li filler-induced rattling of phonon modes and resonant scattering channels, which are validated by the peak features of phonon density of states and scattering rates, efficiently reduce the room temperature thermal conductivity for fully filled structures. Our findings indicate the efficiency of heteroatomic substitution and fillers to engineer the phonon and thermal properties of carbon-based clathrates.
{"title":"Thermal conductivities of ultra-lightweight C12-based type-VII clathrates: an ab initio and comparative study","authors":"Guohui Zheng","doi":"10.1088/1361-6463/acfe1a","DOIUrl":"https://doi.org/10.1088/1361-6463/acfe1a","url":null,"abstract":"Abstract Caged carbon clathrates may have profound applications in thermoelectrics due to their inherent host–guest relations. Using ab initio techniques, we investigate the electronic and phononic properties of type-VII <?CDATA $mathrm{C_{12}}$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:mrow> <mml:msub> <mml:mi mathvariant=\"normal\">C</mml:mi> <mml:mrow> <mml:mn>12</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> clathrate, which is a prototype of the widely studied ternary X –B–C clathrate, and tune its properties using lithium atom filling and boron atom substitution. Upon the introduction of pairwise B substition and a Li filler, the half-filled and fully filled structures retain their semiconducting characteristics due to balanced electron counts; however, their indirect band gaps are reduced. By comparing the phonon and thermal properties of filled and empty structures, we show that B substitution and Li fillers lift the phonon degeneracies, increase the three-phonon scattering phase spaces and eventually cause tenfold reductions in the relaxation time of phonons. The Li filler-induced rattling of phonon modes and resonant scattering channels, which are validated by the peak features of phonon density of states and scattering rates, efficiently reduce the room temperature thermal conductivity for fully filled structures. Our findings indicate the efficiency of heteroatomic substitution and fillers to engineer the phonon and thermal properties of carbon-based clathrates.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"106 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136254324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The emergence of double transition metal MXenes (DTMs) has addressed the challenges associated with the high molar weight and non-metallic characteristics of early transition metal MXenes. In this study, we investigate the performance of WCrC and MoWC, DTMs, as anodes in Li/Mg-ion batteries (LIBs/MIBs) using first-principles calculations. The synergistic effect between the dual metal terminals is analyzed. Our findings reveal that the W terminal provides good electronic conductivity, while the Mo/Cr terminal reduces the molar mass, leading to enhanced energy density. The theoretical capacitance values are 648.81 mAh g −1 (WCrC anode) and 551.82 mAh g −1 (MoWC anode) in LIB, and 432.54 mAh g −1 (WCrC anode) and 367.88 mAh g −1 (MoWC anode) in MIBs. Both anodes exhibit low diffusion barriers with 0.045 eV for Li and 0.079 eV for Mg. They also maintain structural rigidity throughout the battery cycle. This study highlights the crucial role of the dual metal transition terminal synergistic effect in MXenes, influencing adatom adsorption behavior, reducing molar mass, and lowering diffusion barriers. These results contribute to the advancement of MXene surface engineering and offer valuable insights for battery research.
双过渡金属MXenes (DTMs)的出现解决了早期过渡金属MXenes的高摩尔质量和非金属特性带来的挑战。在这项研究中，我们使用第一性原理计算研究了WCrC和MoWC (dtm)作为锂/镁离子电池(LIBs/MIBs)阳极的性能。分析了双金属端子间的协同效应。我们的研究结果表明，W端提供了良好的电子导电性，而Mo/Cr端减少了摩尔质量，从而提高了能量密度。锂离子电池的理论电容值分别为648.81 mAh g−1 (WCrC阳极)和551.82 mAh g−1 (MoWC阳极)，锂离子电池的理论电容值分别为432.54 mAh g−1 (WCrC阳极)和367.88 mAh g−1 (MoWC阳极)。两种阳极均表现出低扩散势垒，Li为0.045 eV, Mg为0.079 eV。它们还可以在整个电池周期中保持结构刚性。该研究强调了双金属过渡端协同效应在MXenes中的关键作用，影响吸附原子的吸附行为，降低摩尔质量，降低扩散障碍。这些结果有助于推进MXene表面工程，并为电池研究提供有价值的见解。
{"title":"Bare W-based MXenes (WCrC and MoWC) Anode with High Specific Capacity for Li and Mg-Ion Batteries","authors":"Min Zhou, Yanqing Shen, Lingling Lv, Yu Zhang, Xianghui Meng, Xin Yang, Qirui He, Bing Zhang, Zhongxiang Zhou","doi":"10.1088/1361-6463/acfe1c","DOIUrl":"https://doi.org/10.1088/1361-6463/acfe1c","url":null,"abstract":"Abstract The emergence of double transition metal MXenes (DTMs) has addressed the challenges associated with the high molar weight and non-metallic characteristics of early transition metal MXenes. In this study, we investigate the performance of WCrC and MoWC, DTMs, as anodes in Li/Mg-ion batteries (LIBs/MIBs) using first-principles calculations. The synergistic effect between the dual metal terminals is analyzed. Our findings reveal that the W terminal provides good electronic conductivity, while the Mo/Cr terminal reduces the molar mass, leading to enhanced energy density. The theoretical capacitance values are 648.81 mAh g −1 (WCrC anode) and 551.82 mAh g −1 (MoWC anode) in LIB, and 432.54 mAh g −1 (WCrC anode) and 367.88 mAh g −1 (MoWC anode) in MIBs. Both anodes exhibit low diffusion barriers with 0.045 eV for Li and 0.079 eV for Mg. They also maintain structural rigidity throughout the battery cycle. This study highlights the crucial role of the dual metal transition terminal synergistic effect in MXenes, influencing adatom adsorption behavior, reducing molar mass, and lowering diffusion barriers. These results contribute to the advancement of MXene surface engineering and offer valuable insights for battery research.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135044045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-09DOI: 10.1088/1361-6463/acfe1b
Xiao Zhang, Zhe Xiong, Bin Tang, Chengtao Yang
Abstract The rapid advancement of mobile communications technology is imposing greater demands on electronic components. Microwave dielectric ceramics with a high dielectric constant ( ϵ r ) are crucial for the miniaturization and integration of microwave devices. Herein, The perovskite-structured (Ca 0.61 Nd 0.26 ) 1− x (Li 0.5 Nd 0.5 ) x TiO 3 (0 ⩽ x ⩽ 0.8) microwave dielectric ceramics with high ϵ r value were prepared by solid-state reaction method. The results demonstrated that the ϵ r value reached its peak at x = 0.6, which was influenced by the bond valence at B-sites. The τ f and Q × f values decreased with increasing x value. Doping (Li 0.5 Nd 0.5 ) 2+ at A-sites led to an increase in the full width at half maximum of Raman peaks, indicating higher internal loss. A high dielectric constant and temperature-stable (Ca 0.61 Nd 0.26 ) 0.27 (Li 0.5 Nd 0.5 ) 0.73 TiO 3 ceramic can be sintered with good microwave dielectric properties of ϵ r = 129.4, Q × f = 2,787 GHz, and τ f = +1.9 ppm/°C.
移动通信技术的飞速发展对电子元器件提出了更高的要求。具有高介电常数(ε)的微波介质陶瓷对于微波器件的小型化和集成化至关重要。本文采用固相反应法制备了高ε值的钙钛矿结构(Ca 0.61 Nd 0.26) 1−x (Li 0.5 Nd 0.5) x tio3(0≤x≤0.8)微波介电陶瓷。结果表明，λ λ在x = 0.6处达到峰值，其值受b位键价的影响。τ f和Q × f值随x值的增大而减小。在a位掺杂(Li 0.5 Nd 0.5) 2+导致拉曼峰半峰全宽度增加，表明内部损耗增加。可以烧结出高介电常数、温度稳定(Ca 0.61 Nd 0.26) 0.27 (Li 0.5 Nd 0.5) 0.73的tio3陶瓷，其微波介电性能良好，ε r = 129.4, Q × f = 2,787 GHz， τ f = +1.9 ppm/°C。
{"title":"Effects of (Li0.5Nd0.5)2+ on the phase evolution, Raman spectra and microwave dielectric properties in CaO–Nd2O3–TiO2 ceramic","authors":"Xiao Zhang, Zhe Xiong, Bin Tang, Chengtao Yang","doi":"10.1088/1361-6463/acfe1b","DOIUrl":"https://doi.org/10.1088/1361-6463/acfe1b","url":null,"abstract":"Abstract The rapid advancement of mobile communications technology is imposing greater demands on electronic components. Microwave dielectric ceramics with a high dielectric constant ( ϵ r ) are crucial for the miniaturization and integration of microwave devices. Herein, The perovskite-structured (Ca 0.61 Nd 0.26 ) 1− x (Li 0.5 Nd 0.5 ) x TiO 3 (0 ⩽ x ⩽ 0.8) microwave dielectric ceramics with high ϵ r value were prepared by solid-state reaction method. The results demonstrated that the ϵ r value reached its peak at x = 0.6, which was influenced by the bond valence at B-sites. The τ f and Q × f values decreased with increasing x value. Doping (Li 0.5 Nd 0.5 ) 2+ at A-sites led to an increase in the full width at half maximum of Raman peaks, indicating higher internal loss. A high dielectric constant and temperature-stable (Ca 0.61 Nd 0.26 ) 0.27 (Li 0.5 Nd 0.5 ) 0.73 TiO 3 ceramic can be sintered with good microwave dielectric properties of ϵ r = 129.4, Q × f = 2,787 GHz, and τ f = +1.9 ppm/°C.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135044046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-09DOI: 10.1088/1361-6463/acfcc7
Li Lin, Sophia Gershman, Yevgeny Raitses, Michael Keidar
Abstract Cold atmospheric plasma (CAP) in open air hosts numerous chemical species engaged in thousands of chemical reactions. Comprehensive diagnosis of its chemical composition is important across various fields from medicine, where reactive oxygen and nitrogen play key roles, to surface modification. In applications, a centimeter-scale helium–air jet operates for minutes, featuring micrometer-sized streamers and an atmospheric pressure-induced collision frequency in the hundreds of GHz range. To address this intricate multi-scale issue, we introduce a machine learning approach: using a physics-informed neural network (PINN) to tackle the multi-scale complexities inherent in predicting the complete list of species concentrations, gas temperature, and electron temperature of a CAP jet supplied with a mixture of helium and air. Experimental measurements of O 3 , N 2 O, and NO 2 concentrations downstream of the plasma jet, combined with fundamental physics laws, the conservation of mass and charge, constrain the PINN, enabling it to predict the concentrations of all species that are not available from the experiment, along with gas and electron temperatures. The results, therefore, obey all the physical laws we provided and can have a chemical balance with the measured concentrations. This methodology holds promise for describing and potentially regulating complex systems with limited experimental datasets.
{"title":"Data-driven prediction of the output composition of an atmospheric pressure plasma jet","authors":"Li Lin, Sophia Gershman, Yevgeny Raitses, Michael Keidar","doi":"10.1088/1361-6463/acfcc7","DOIUrl":"https://doi.org/10.1088/1361-6463/acfcc7","url":null,"abstract":"Abstract Cold atmospheric plasma (CAP) in open air hosts numerous chemical species engaged in thousands of chemical reactions. Comprehensive diagnosis of its chemical composition is important across various fields from medicine, where reactive oxygen and nitrogen play key roles, to surface modification. In applications, a centimeter-scale helium–air jet operates for minutes, featuring micrometer-sized streamers and an atmospheric pressure-induced collision frequency in the hundreds of GHz range. To address this intricate multi-scale issue, we introduce a machine learning approach: using a physics-informed neural network (PINN) to tackle the multi-scale complexities inherent in predicting the complete list of species concentrations, gas temperature, and electron temperature of a CAP jet supplied with a mixture of helium and air. Experimental measurements of O 3 , N 2 O, and NO 2 concentrations downstream of the plasma jet, combined with fundamental physics laws, the conservation of mass and charge, constrain the PINN, enabling it to predict the concentrations of all species that are not available from the experiment, along with gas and electron temperatures. The results, therefore, obey all the physical laws we provided and can have a chemical balance with the measured concentrations. This methodology holds promise for describing and potentially regulating complex systems with limited experimental datasets.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135043501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The electron density is a key parameter to characterize any plasma. Most of the plasma applications and research in the area of low-temperature plasmas (LTPs) are based on the accurate estimations of plasma density and plasma temperature. The conventional methods for electron density measurements offer axial and radial profiles for any given linear LTP device. These methods have major disadvantages of operational range (not very wide), cumbersome instrumentation, and complicated data analysis procedures. The article proposes a deep learning (DL) assisted microwave-plasma interaction-based non-invasive strategy, which can be used as a new alternative approach to address some of the challenges associated with existing plasma density measurement techniques. The electric field pattern due to microwave scattering from plasma is utilized to estimate the density profile. The proof of concept is tested for a simulated training data set comprising a low-temperature, unmagnetized, collisional plasma. Different types of symmetric (Gaussian-shaped) and asymmetrical density profiles, in the range 10 16 –10 19 m −3 , addressing a range of experimental configurations have been considered in our study. Real-life experimental issues such as the presence of noise and the amount of measured data (dense vs sparse) have been taken into consideration while preparing the synthetic training data-sets. The DL-based technique has the capability to determine the electron density profile within the plasma. The performance of the proposed DL-based approach has been evaluated using three metrics- structural similarity index, root mean square logarithmic error, and mean absolute percentage error. The obtained results show promising performance in estimating the 2D radial profile of the density for the given linear plasma device and affirms the potential of the proposed machine learning-based approach in plasma diagnostics.
{"title":"Deep Learning assisted microwave-plasma interaction based technique for plasma density estimation","authors":"Pratik Ghosh, Bhaskar Chaudhury, Shishir Purohit, Vishv Joshi, Ashray Kothari, Devdeep Shetranjiwala","doi":"10.1088/1361-6463/acfdb6","DOIUrl":"https://doi.org/10.1088/1361-6463/acfdb6","url":null,"abstract":"Abstract The electron density is a key parameter to characterize any plasma. Most of the plasma applications and research in the area of low-temperature plasmas (LTPs) are based on the accurate estimations of plasma density and plasma temperature. The conventional methods for electron density measurements offer axial and radial profiles for any given linear LTP device. These methods have major disadvantages of operational range (not very wide), cumbersome instrumentation, and complicated data analysis procedures. The article proposes a deep learning (DL) assisted microwave-plasma interaction-based non-invasive strategy, which can be used as a new alternative approach to address some of the challenges associated with existing plasma density measurement techniques. The electric field pattern due to microwave scattering from plasma is utilized to estimate the density profile. The proof of concept is tested for a simulated training data set comprising a low-temperature, unmagnetized, collisional plasma. Different types of symmetric (Gaussian-shaped) and asymmetrical density profiles, in the range 10 16 –10 19 m −3 , addressing a range of experimental configurations have been considered in our study. Real-life experimental issues such as the presence of noise and the amount of measured data (dense vs sparse) have been taken into consideration while preparing the synthetic training data-sets. The DL-based technique has the capability to determine the electron density profile within the plasma. The performance of the proposed DL-based approach has been evaluated using three metrics- structural similarity index, root mean square logarithmic error, and mean absolute percentage error. The obtained results show promising performance in estimating the 2D radial profile of the density for the given linear plasma device and affirms the potential of the proposed machine learning-based approach in plasma diagnostics.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135044185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-09DOI: 10.1088/1361-6463/ad015d
Cónal Murphy, Eoin P O'Reilly, Christopher A Broderick
We present a theoretical analysis of mid-infrared radiative recombination in InAs/GaSb superlattices (SLs). We employ a semi-analytical plane wave expansion method in conjunction with an 8-band $mathbf{k} cdot mathbf{p}$ Hamiltonian to compute the SL electronic structure, paying careful attention to the identification and mitigation of spurious solutions. The calculated SL eigenstates are used directly to compute spontaneous emission spectra and the radiative recombination coefficient $B$. We elucidate the origin of the relatively large $B$ coefficients in InAs/GaSb SLs which, despite the presence of spatially indirect (type-II-like) carrier confinement, are close to that of bulk InAs and compare favourably to those calculated for mid-infrared type-I pseudomorphic and metamorphic quantum well structures having comparable emission wavelengths. Our analysis explicitly quantifies the roles played by carrier localisation (specifically, partial delocalisation of bound electron states) and miniband formation (specifically, miniband occupation and optical selection rules) in determining the magnitude of $B$ and its temperature dependence. We perform a high-throughput optimisation of the room temperature $B$ coefficient in InAs/GaSb SLs across the 3.5 -- 7 $mu$m wavelength range, quantifying the dependence of $B$ on the relative thickness of the electron-confining InAs and hole-confining GaSb layers. This analysis provides guidance for the growth of optimised SLs for mid-infrared light emitters. Our results, combined with the expected low non-radiative Auger recombination rates in structures having spatially indirect electron and hole confinement, corroborate recently observed high output power in prototype InAs/GaSb SL inter-band cascade light-emitting diodes.
{"title":"Theory and optimisation of radiative recombination in broken-gap InAs/GaSb superlattices","authors":"Cónal Murphy, Eoin P O'Reilly, Christopher A Broderick","doi":"10.1088/1361-6463/ad015d","DOIUrl":"https://doi.org/10.1088/1361-6463/ad015d","url":null,"abstract":"We present a theoretical analysis of mid-infrared radiative recombination in InAs/GaSb superlattices (SLs). We employ a semi-analytical plane wave expansion method in conjunction with an 8-band $mathbf{k} cdot mathbf{p}$ Hamiltonian to compute the SL electronic structure, paying careful attention to the identification and mitigation of spurious solutions. The calculated SL eigenstates are used directly to compute spontaneous emission spectra and the radiative recombination coefficient $B$. We elucidate the origin of the relatively large $B$ coefficients in InAs/GaSb SLs which, despite the presence of spatially indirect (type-II-like) carrier confinement, are close to that of bulk InAs and compare favourably to those calculated for mid-infrared type-I pseudomorphic and metamorphic quantum well structures having comparable emission wavelengths. Our analysis explicitly quantifies the roles played by carrier localisation (specifically, partial delocalisation of bound electron states) and miniband formation (specifically, miniband occupation and optical selection rules) in determining the magnitude of $B$ and its temperature dependence. We perform a high-throughput optimisation of the room temperature $B$ coefficient in InAs/GaSb SLs across the 3.5 -- 7 $mu$m wavelength range, quantifying the dependence of $B$ on the relative thickness of the electron-confining InAs and hole-confining GaSb layers. This analysis provides guidance for the growth of optimised SLs for mid-infrared light emitters. Our results, combined with the expected low non-radiative Auger recombination rates in structures having spatially indirect electron and hole confinement, corroborate recently observed high output power in prototype InAs/GaSb SL inter-band cascade light-emitting diodes.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135044596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Intelligent wearable electronics have gained considerable research interest as it presents a huge market prospect. As the fundamental component of wearable electronics, patterned electrodes play a key role as it combines advantages such as mechanical flexibility, multiple functions, and cost-effectiveness. Patterned electrodes have drawn attention due to their wide application potential for wearable electronics and other devices. Herein, we briefly summarized the recent reports on the classification of fabrication methods for patterned electrodes, and their applications in wearable human movements detection sensors, optoelectronic devices, and energy harvesting devices. Finally, with the development of fabrication methods that combine advantages such as multifunctional, short fabricating cycles, and cost efficiency, the trend of multifunctional integration has great value in the field of wearable electronics.
{"title":"Recent progress of patterned electrodes in wearable electronics: fabrication and application","authors":"Xin-Ran Zhang, Hai-Tao Deng, Xu Zeng, Yi-Lin Wang, Peng Huang, Xiao-Sheng Zhang","doi":"10.1088/1361-6463/acfaac","DOIUrl":"https://doi.org/10.1088/1361-6463/acfaac","url":null,"abstract":"Abstract Intelligent wearable electronics have gained considerable research interest as it presents a huge market prospect. As the fundamental component of wearable electronics, patterned electrodes play a key role as it combines advantages such as mechanical flexibility, multiple functions, and cost-effectiveness. Patterned electrodes have drawn attention due to their wide application potential for wearable electronics and other devices. Herein, we briefly summarized the recent reports on the classification of fabrication methods for patterned electrodes, and their applications in wearable human movements detection sensors, optoelectronic devices, and energy harvesting devices. Finally, with the development of fabrication methods that combine advantages such as multifunctional, short fabricating cycles, and cost efficiency, the trend of multifunctional integration has great value in the field of wearable electronics.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135302598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The search for an ecofriendly treatment for the strong greenhouse gas SF 6 has become a global hot issue. Herein, the mixed-terminal Ti 3 C 2 T x MXene catalyzing conversion of SF 6 in aqueous solution was explored. The catalytic network on realistic Ti 3 C 2 T x was constructed. By theoretical calculations, target products and the microscopic reaction mechanism were studied. Firstly, SF 6 exhibited different degrees of chemisorption on the constructed Ti 3 C 2 T x surfaces of three varying terminal proportions, with different terminals showing synergistic effects. Secondly, taking the effect of H 2 O and surface hydroxyl into account, the catalytic conversion system of SF 6 on a Ti 3 C 2 (OH) 0.66 O 1.33 surface was constructed, containing 25 sub-reactions with H 2 S as one of the final products. SF 6 went through successive defluorination on the Ti 3 C 2 (OH) 0.66 O 1.33 surface to form low-fluorine sulfide SF x ( x = 5, 4, 3, 2, 1), with energy of 80.685 kcal mol −1 released during the whole process. The energy barriers of all the SF 6 decomposition sub-reactions were significantly lower than that in free space. Besides, O terminals were regarded as potential hydroxyl terminals in aqueous solution, which continuously provided active hydroxyl groups for the Ti 3 C 2 (OH) 0.66 O 1.33 surface. Thus, SF 6 conversion in aqueous solution will not result in deactivation of Ti 3 C 2 T x catalyst. This work provides a theoretical basis for MXene to catalyze SF 6 decomposition in an efficient way.
寻找强温室气体sf6的环保处理方法已成为全球热点问题。本文研究了混合端ti3c2txmxene在水溶液中催化sf6的转化。在真实的ti3c2tx上构建了催化网络。通过理论计算，对目标产物和微观反应机理进行了研究。首先，sf6在构建的三种不同末端比例的ti3c2tx表面表现出不同程度的化学吸附，不同的末端表现出协同效应。其次，考虑到h2o和表面羟基的影响，构建了sf6在Ti 3c_2 (OH) 0.66 O 1.33表面上的催化转化体系，该体系包含25个亚反应，最终产物之一为h2s。sf6在Ti 3 C 2 (OH) 0.66 O 1.33表面连续脱氟生成低氟硫化物sfx (x = 5,4,3,2,1)，整个过程释放能量为80.685 kcal mol−1。SF - 6分解亚反应的能垒均明显低于自由空间。此外，O端被认为是水溶液中潜在的羟基端，它不断地为Ti 3c (OH) 0.66 O 1.33表面提供活性羟基。因此，sf6在水溶液中的转化不会导致ti3c2tx催化剂失活。本研究为MXene高效催化sf6分解提供了理论基础。
{"title":"Mixed terminal MXenes react with SF6 in aqueous solution: reaction mechanism and pathway","authors":"Fuping Zeng, Xinnuo Guo, Xiaoyue Chen, Kexin Zhu, Hao Qiu, Shiling Zhang, Ju Tang","doi":"10.1088/1361-6463/acf9b4","DOIUrl":"https://doi.org/10.1088/1361-6463/acf9b4","url":null,"abstract":"Abstract The search for an ecofriendly treatment for the strong greenhouse gas SF 6 has become a global hot issue. Herein, the mixed-terminal Ti 3 C 2 T x MXene catalyzing conversion of SF 6 in aqueous solution was explored. The catalytic network on realistic Ti 3 C 2 T x was constructed. By theoretical calculations, target products and the microscopic reaction mechanism were studied. Firstly, SF 6 exhibited different degrees of chemisorption on the constructed Ti 3 C 2 T x surfaces of three varying terminal proportions, with different terminals showing synergistic effects. Secondly, taking the effect of H 2 O and surface hydroxyl into account, the catalytic conversion system of SF 6 on a Ti 3 C 2 (OH) 0.66 O 1.33 surface was constructed, containing 25 sub-reactions with H 2 S as one of the final products. SF 6 went through successive defluorination on the Ti 3 C 2 (OH) 0.66 O 1.33 surface to form low-fluorine sulfide SF x ( x = 5, 4, 3, 2, 1), with energy of 80.685 kcal mol −1 released during the whole process. The energy barriers of all the SF 6 decomposition sub-reactions were significantly lower than that in free space. Besides, O terminals were regarded as potential hydroxyl terminals in aqueous solution, which continuously provided active hydroxyl groups for the Ti 3 C 2 (OH) 0.66 O 1.33 surface. Thus, SF 6 conversion in aqueous solution will not result in deactivation of Ti 3 C 2 T x catalyst. This work provides a theoretical basis for MXene to catalyze SF 6 decomposition in an efficient way.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135302898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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