Purcell filters, which serve to suppress electromagnetic radiation and enhance the readout efficiency of qubit, are an indispensable component in superconducting quantum chips. With the increasing scale of quantum chips, the requirements for the performance and scalability of Purcell filters are becoming more stringent. In this report, a novel four-stage Purcell filter that enables fast measurement without exacerbating environmental damping of the qubits is presented. The design approach of the filter is derived from the serial and parallel configurations of λ/4 resonant cavities. The filter exhibits exceptional passband-to-stopband isolation, reaching up to 40 dB of isolation within the transition range of 400 MHz. Furthermore, the filter boasts a wide bandwidth for both the stopband and the passband, with the stopband ranging from 4 to 5.5 GHz and the passband extending from 5.8 to 6.5 GHz. In terms of spatial arrangement, each filter can be connected to over ten readout resonators for qubit readout. This innovative Purcell filter will significantly contribute to the development of high quality, scalable superconducting quantum chips.
{"title":"High-suppression-ratio and wide bandwidth four-stage Purcell filter for multiplexed superconducting qubit readout","authors":"Yibiao Zhou, Xiao Cai, Yuzhen Zheng, Boyi Zhou, Yu Wang, Kanglin Xiong, Jiagui Feng","doi":"10.1063/5.0173539","DOIUrl":"https://doi.org/10.1063/5.0173539","url":null,"abstract":"Purcell filters, which serve to suppress electromagnetic radiation and enhance the readout efficiency of qubit, are an indispensable component in superconducting quantum chips. With the increasing scale of quantum chips, the requirements for the performance and scalability of Purcell filters are becoming more stringent. In this report, a novel four-stage Purcell filter that enables fast measurement without exacerbating environmental damping of the qubits is presented. The design approach of the filter is derived from the serial and parallel configurations of λ/4 resonant cavities. The filter exhibits exceptional passband-to-stopband isolation, reaching up to 40 dB of isolation within the transition range of 400 MHz. Furthermore, the filter boasts a wide bandwidth for both the stopband and the passband, with the stopband ranging from 4 to 5.5 GHz and the passband extending from 5.8 to 6.5 GHz. In terms of spatial arrangement, each filter can be connected to over ten readout resonators for qubit readout. This innovative Purcell filter will significantly contribute to the development of high quality, scalable superconducting quantum chips.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"102 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139408670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
X. Y. Luo, A. O'Hara, X. Li, P. F. Wang, E. X. Zhang, R. D. Schrimpf, S. T. Pantelides, D. M. Fleetwood
Current–voltage characteristics and low-frequency (LF) noise of industrial-quality AlGaAs/InGaAs/GaAs pseudomorphic high-electron-mobility transistors are evaluated as a function of bias stress and temperature. A small positive shift of threshold voltage Vth and negligible degradation in peak transconductance GM are observed under ON-state bias conditions at elevated temperatures. The Vth measurements suggest activation of an acceptor-like defect or impurity center. The GM measurements demonstrate that newly activated defects are not located close enough to the two-dimensional electron gas to scatter carriers strongly. First-principles calculations and comparisons with previous work suggest that OAs impurity centers, other oxygen-related defects, isolated AsGa antisites, and dopant-based DX centers may contribute significantly to low-frequency (LF) noise in as-processed devices. LF noise is relatively unaffected by voltage stress at elevated temperatures, consistent with the small changes in Vth and peak GM.
{"title":"Low-frequency noise and defects in AlGaAs/InGaAs/GaAs pseudomorphic high-electron mobility transistors","authors":"X. Y. Luo, A. O'Hara, X. Li, P. F. Wang, E. X. Zhang, R. D. Schrimpf, S. T. Pantelides, D. M. Fleetwood","doi":"10.1063/5.0187747","DOIUrl":"https://doi.org/10.1063/5.0187747","url":null,"abstract":"Current–voltage characteristics and low-frequency (LF) noise of industrial-quality AlGaAs/InGaAs/GaAs pseudomorphic high-electron-mobility transistors are evaluated as a function of bias stress and temperature. A small positive shift of threshold voltage Vth and negligible degradation in peak transconductance GM are observed under ON-state bias conditions at elevated temperatures. The Vth measurements suggest activation of an acceptor-like defect or impurity center. The GM measurements demonstrate that newly activated defects are not located close enough to the two-dimensional electron gas to scatter carriers strongly. First-principles calculations and comparisons with previous work suggest that OAs impurity centers, other oxygen-related defects, isolated AsGa antisites, and dopant-based DX centers may contribute significantly to low-frequency (LF) noise in as-processed devices. LF noise is relatively unaffected by voltage stress at elevated temperatures, consistent with the small changes in Vth and peak GM.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"1 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139409190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maria-Thaleia Passia, Traianos V. Yioultsis, Emmanouil E. Kriezis
We derive a coupled-mode theory (CMT) formulation for the fast analysis of periodic multi-element metasurfaces in the presence of radiation losses. Full-wave simulations of periodic multi-element metasurfaces are very time- and memory-consuming, especially as the size and complexity of the metasurface increase. The CMT formulation provides a considerably faster and efficient alternative. It results in a small system of equations with size equal to the number of supported resonator modes in the frequency range of interest, allowing to calculate the resonator mode amplitudes and, consequently, the metasurface response. Subsequently, we systematically derive analytical closed-form expressions for the coupling coefficients between two weakly coupled resonators in the presence of radiation losses and incorporate them into the CMT model, which is found important for the accurate description of the metasurface, while also providing insight into the underlying physics of complex metasurfaces. We validate the proposed formulation on benchmark examples of both metal- and dielectric-based metasurface absorbers (MSAs) by comparing the CMT results to spectral FEM simulations of the composing supercell. To further demonstrate the potential of the proposed formulation, as a proof of concept, we use the CMT to synthesize a larger optimized periodic multi-element MSA. A comprehensive comparison to full-wave FEM simulations of the composing supercell is included in terms of time and computational requirements, which shows that our method provides a valuable and efficient alternative solver for synthesizing complex metasurfaces.
{"title":"A coupled-mode-theory formulation for periodic multi-element metasurfaces in the presence of radiation losses","authors":"Maria-Thaleia Passia, Traianos V. Yioultsis, Emmanouil E. Kriezis","doi":"10.1063/5.0179442","DOIUrl":"https://doi.org/10.1063/5.0179442","url":null,"abstract":"We derive a coupled-mode theory (CMT) formulation for the fast analysis of periodic multi-element metasurfaces in the presence of radiation losses. Full-wave simulations of periodic multi-element metasurfaces are very time- and memory-consuming, especially as the size and complexity of the metasurface increase. The CMT formulation provides a considerably faster and efficient alternative. It results in a small system of equations with size equal to the number of supported resonator modes in the frequency range of interest, allowing to calculate the resonator mode amplitudes and, consequently, the metasurface response. Subsequently, we systematically derive analytical closed-form expressions for the coupling coefficients between two weakly coupled resonators in the presence of radiation losses and incorporate them into the CMT model, which is found important for the accurate description of the metasurface, while also providing insight into the underlying physics of complex metasurfaces. We validate the proposed formulation on benchmark examples of both metal- and dielectric-based metasurface absorbers (MSAs) by comparing the CMT results to spectral FEM simulations of the composing supercell. To further demonstrate the potential of the proposed formulation, as a proof of concept, we use the CMT to synthesize a larger optimized periodic multi-element MSA. A comprehensive comparison to full-wave FEM simulations of the composing supercell is included in terms of time and computational requirements, which shows that our method provides a valuable and efficient alternative solver for synthesizing complex metasurfaces.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"5 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139409228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Reliable nanoswitch operation requires low contact voltages and stable electrical contact resistance (ECR). Surface cleanliness is crucial to prevent nanomechanical switch failure, which can occur due to the presence of insulating adventitious hydrocarbon films. In situ O2 plasma cleaning is effective but oxidizes metal surfaces. Here, the noble metal Pt, which forms PtOx, is employed to form electrodes. Previous studies report on PtOx electrical resistivity, but the effects of PtOx evolution at contacting interfaces due to electrical and mechanical stimuli have not been explored. This study investigates the impact of PtOx on ECR at low contact voltages under hot switching, cold switching, and mechanical cycling conditions. An increase in ECR upon plasma cleaning indicates the presence of a resistive PtOx layer. After hot and cold switch cycling at applied voltages of 300 mV or less, a low stable ECR is achieved. A higher contact voltage accelerates ECR stabilization. The results are consistent with PtOx film volatilization, which is primarily due to Joule heating rather than mechanical rupture. This investigation advances the understanding of interface evolution in plasma-cleaned nanoswitches.
{"title":"Low voltage cold and hot switching in nanoswitches cleaned by in situ oxygen plasma can achieve low stable contact resistance","authors":"Deepak Kumar, Casey M. Walker, Maarten P. de Boer","doi":"10.1063/5.0179167","DOIUrl":"https://doi.org/10.1063/5.0179167","url":null,"abstract":"Reliable nanoswitch operation requires low contact voltages and stable electrical contact resistance (ECR). Surface cleanliness is crucial to prevent nanomechanical switch failure, which can occur due to the presence of insulating adventitious hydrocarbon films. In situ O2 plasma cleaning is effective but oxidizes metal surfaces. Here, the noble metal Pt, which forms PtOx, is employed to form electrodes. Previous studies report on PtOx electrical resistivity, but the effects of PtOx evolution at contacting interfaces due to electrical and mechanical stimuli have not been explored. This study investigates the impact of PtOx on ECR at low contact voltages under hot switching, cold switching, and mechanical cycling conditions. An increase in ECR upon plasma cleaning indicates the presence of a resistive PtOx layer. After hot and cold switch cycling at applied voltages of 300 mV or less, a low stable ECR is achieved. A higher contact voltage accelerates ECR stabilization. The results are consistent with PtOx film volatilization, which is primarily due to Joule heating rather than mechanical rupture. This investigation advances the understanding of interface evolution in plasma-cleaned nanoswitches.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"51 12 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139408711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C4F7N/CO2 gas mixtures have attracted extensive attention because of their excellent insulating properties and environmental friendliness. High electrical and thermal stability is an important indicator for evaluating their performance, but there have been few molecular dynamics studies of their decomposition mechanisms. In this study, using ReaxFF molecular dynamics simulations and quantum chemistry theory, the decomposition mechanism of a C4F7N/CO2 gas mixture and the effect of the O2 content on the decomposition of the mixture were simulated on the microscopic level. It was found that there are three main decomposition pathways of C4F7N molecules, of which the generation of C3F4N⋅ and CF3⋅ free radicals is the most likely to occur. COF2 is the main oxygen-containing product of the C4F7N/CO2 gas mixture, and its generation is significantly affected by the simulation time and temperature. COF2 can be regarded as the characteristic decomposition product of the C4F7N/CO2 gas mixture. The addition of O2 slightly promotes the decomposition of C4F7N, whereas the maximum decomposition rate of CO2 decreases by 0.3% and 1% after the addition of 2% and 8% O2, respectively. Relevant results of this research can provide a theoretical basis and guidance for research into the performance of C4F7N/CO2 gas mixtures and practical engineering applications of these mixtures in the future.
{"title":"Decomposition mechanism of C4F7N/CO2 gas mixture based on molecular dynamics and effect of O2 content","authors":"Danchen Zhao, Jing Yan, Ruixin He, Yingsan Geng, Zhiyuan Liu, Jianhua Wang","doi":"10.1063/5.0174959","DOIUrl":"https://doi.org/10.1063/5.0174959","url":null,"abstract":"C4F7N/CO2 gas mixtures have attracted extensive attention because of their excellent insulating properties and environmental friendliness. High electrical and thermal stability is an important indicator for evaluating their performance, but there have been few molecular dynamics studies of their decomposition mechanisms. In this study, using ReaxFF molecular dynamics simulations and quantum chemistry theory, the decomposition mechanism of a C4F7N/CO2 gas mixture and the effect of the O2 content on the decomposition of the mixture were simulated on the microscopic level. It was found that there are three main decomposition pathways of C4F7N molecules, of which the generation of C3F4N⋅ and CF3⋅ free radicals is the most likely to occur. COF2 is the main oxygen-containing product of the C4F7N/CO2 gas mixture, and its generation is significantly affected by the simulation time and temperature. COF2 can be regarded as the characteristic decomposition product of the C4F7N/CO2 gas mixture. The addition of O2 slightly promotes the decomposition of C4F7N, whereas the maximum decomposition rate of CO2 decreases by 0.3% and 1% after the addition of 2% and 8% O2, respectively. Relevant results of this research can provide a theoretical basis and guidance for research into the performance of C4F7N/CO2 gas mixtures and practical engineering applications of these mixtures in the future.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"56 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139409222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Active thermography using pulsed heating is a fast and reliable method for detecting flaws in composite and metallic materials. This paper analyzes the temperature decay that occurs immediately after flash heating the front surface of stainless steel specimens as a function of time, based on a novel application of the equivalent circuit approach (ECA). The temperature decay from the front surface is equated to the discharge of a capacitor. The ECA is based on the charging (temperature rise due to flash heating) of a capacitor, followed by its discharge (temperature decay) through a series of resistors (which depends on the conductivity of the material) and capacitance (which depends on the thermal capacitance of the layers) through which the heat is dissipated. The proposed approach analyzes the sequences of temperature data obtained at each pixel location during cooling from a step wedge and a specimen with multiple flat-bottom holes. Time constant maps derived from the analysis are used to ascertain the thickness of the step wedge, detect the flaws, and evaluate the remnant thickness of the flaws. A correlation has been established between the thickness and the time constants. The above approach has been used to estimate the diameter of the flat-bottom holes.
{"title":"An equivalent circuit approach for remnant thickness evaluation and flaw sizing using pulsed thermography","authors":"Govind K. Sharma, S Mahadevan, Anish Kumar","doi":"10.1063/5.0166652","DOIUrl":"https://doi.org/10.1063/5.0166652","url":null,"abstract":"Active thermography using pulsed heating is a fast and reliable method for detecting flaws in composite and metallic materials. This paper analyzes the temperature decay that occurs immediately after flash heating the front surface of stainless steel specimens as a function of time, based on a novel application of the equivalent circuit approach (ECA). The temperature decay from the front surface is equated to the discharge of a capacitor. The ECA is based on the charging (temperature rise due to flash heating) of a capacitor, followed by its discharge (temperature decay) through a series of resistors (which depends on the conductivity of the material) and capacitance (which depends on the thermal capacitance of the layers) through which the heat is dissipated. The proposed approach analyzes the sequences of temperature data obtained at each pixel location during cooling from a step wedge and a specimen with multiple flat-bottom holes. Time constant maps derived from the analysis are used to ascertain the thickness of the step wedge, detect the flaws, and evaluate the remnant thickness of the flaws. A correlation has been established between the thickness and the time constants. The above approach has been used to estimate the diameter of the flat-bottom holes.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"17 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139409513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Magnetoelectric (ME) effects in a ferromagnetic and piezoelectric composite are the changes in the polarization caused by a magnetic field or the changes in the magnetization caused by an electric field. These effects are aided by the mechanical deformation in the ferroic phases caused by the combination of magnetostriction and piezoelectricity. Interest in ME effects is due to a variety of physical phenomena they exhibit, as well as their potential applications in the creation of highly sensitive magnetic field sensors and other electronic devices. Linear ME effects in structures with layers of different ferroic materials have been studied extensively. However, nonlinear ME effects, which are caused by the nonlinearity of the magnetic, dielectric, and acoustic properties of ferromagnets and piezoelectrics, are less well understood. The purpose of this review is to summarize the current state of knowledge on nonlinear ME (NLME) effects in composite heterostructures and to discuss their potential applications. The review begins by discussing the characteristics of materials that are conductive to the occurrence of NLME effects and ferromagnetic-piezoelectric materials that are most commonly used to study such effects. The review then provides details on theoretical approaches to the description of NLME effects in heterostructures and experimental methods for studying these effects. Finally, the review presents a chronological overview of the experimentally observed NLME effects in composite structures excited by low-frequency and pulsed magnetic or electric fields. The review concludes with a discussion on the potential applications of NLME effects for highly sensitive magnetic field sensors.
铁磁和压电复合材料中的磁电效应（ME）是指磁场引起的极化变化或电场引起的磁化变化。这些效应得益于磁致伸缩性和压电性共同作用下铁磁相的机械变形。人们之所以对 ME 效应感兴趣，是因为它们所表现出的各种物理现象，以及它们在制造高灵敏度磁场传感器和其他电子设备方面的潜在应用。人们已经对具有不同铁性材料层的结构中的线性 ME 效应进行了广泛研究。然而，由铁磁体和压电体的磁性、介电性和声学特性的非线性所引起的非线性 ME 效应却不那么为人所知。本综述旨在总结复合异质结构中非线性 ME（NLME）效应的知识现状，并讨论其潜在应用。综述首先讨论了对 NLME 效应发生具有传导性的材料特性，以及最常用于研究此类效应的铁磁压电材料。然后，综述详细介绍了描述异质结构中 NLME 效应的理论方法和研究这些效应的实验方法。最后，综述按时间顺序概述了在低频和脉冲磁场或电场激励下，在复合结构中观察到的 NLME 效应。综述最后讨论了 NLME 效应在高灵敏磁场传感器中的潜在应用。
{"title":"Nonlinear magnetoelectric effects in layered multiferroic composites","authors":"Y. K. Fetisov, G. Srinivasan","doi":"10.1063/5.0183351","DOIUrl":"https://doi.org/10.1063/5.0183351","url":null,"abstract":"Magnetoelectric (ME) effects in a ferromagnetic and piezoelectric composite are the changes in the polarization caused by a magnetic field or the changes in the magnetization caused by an electric field. These effects are aided by the mechanical deformation in the ferroic phases caused by the combination of magnetostriction and piezoelectricity. Interest in ME effects is due to a variety of physical phenomena they exhibit, as well as their potential applications in the creation of highly sensitive magnetic field sensors and other electronic devices. Linear ME effects in structures with layers of different ferroic materials have been studied extensively. However, nonlinear ME effects, which are caused by the nonlinearity of the magnetic, dielectric, and acoustic properties of ferromagnets and piezoelectrics, are less well understood. The purpose of this review is to summarize the current state of knowledge on nonlinear ME (NLME) effects in composite heterostructures and to discuss their potential applications. The review begins by discussing the characteristics of materials that are conductive to the occurrence of NLME effects and ferromagnetic-piezoelectric materials that are most commonly used to study such effects. The review then provides details on theoretical approaches to the description of NLME effects in heterostructures and experimental methods for studying these effects. Finally, the review presents a chronological overview of the experimentally observed NLME effects in composite structures excited by low-frequency and pulsed magnetic or electric fields. The review concludes with a discussion on the potential applications of NLME effects for highly sensitive magnetic field sensors.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"23 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139408667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The effect of inserting a nm-scale layer of Zn(Si,Ge)N2 into an AlGaN quantum well structure designed for light emission in the wavelength range from 255 to 305 nm is investigated here. The enhanced confinement of the hole within the quantum well results in an enhancement of the overlap of the hole and electron wave functions, resulting in an enhancement of the radiative recombination rate. In this theoretical calculation, for emission at a 270 nm wavelength, the enhancement in the wavefunction overlap can reach a factor of 7 when compared to an AlGaN quantum well device specifically engineered for optimal emission at the identical wavelength. Increases of almost an order of magnitude in both the peak spontaneous emission intensity and the radiative recombination rate are predicted. The peak emission wavelength can be tuned from 255 to 305 nm by adjusting the width and/or the composition of the inserted layer. The proposed structures provide a route to higher efficiency ultraviolet practical light emitting diodes and lasers.
{"title":"Design of AlGaN-Zn(Si,Ge)N2 quantum wells for high-efficiency ultraviolet light emitters","authors":"Chenxi Hu, Kathleen Kash, Hongping Zhao","doi":"10.1063/5.0182716","DOIUrl":"https://doi.org/10.1063/5.0182716","url":null,"abstract":"The effect of inserting a nm-scale layer of Zn(Si,Ge)N2 into an AlGaN quantum well structure designed for light emission in the wavelength range from 255 to 305 nm is investigated here. The enhanced confinement of the hole within the quantum well results in an enhancement of the overlap of the hole and electron wave functions, resulting in an enhancement of the radiative recombination rate. In this theoretical calculation, for emission at a 270 nm wavelength, the enhancement in the wavefunction overlap can reach a factor of 7 when compared to an AlGaN quantum well device specifically engineered for optimal emission at the identical wavelength. Increases of almost an order of magnitude in both the peak spontaneous emission intensity and the radiative recombination rate are predicted. The peak emission wavelength can be tuned from 255 to 305 nm by adjusting the width and/or the composition of the inserted layer. The proposed structures provide a route to higher efficiency ultraviolet practical light emitting diodes and lasers.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"9 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139408759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Paulo Victor Sciammarella, Matheus Almeida de Souza, Luciano de Moura Guimarães, Maria Ivonete Nogueira da Silva, Juan Carlos González Pérez, Leandro Gutierrez Rizzi, Eduardo Nery Duarte Araujo
Due to the growing demand for miniaturization and energy efficiency in modern electronic devices, there is a renewed interest for optoelectronic memories and sensors based on 2D materials. In particular, the molybdenum ditelluride (MoTe2) is one of the most promising materials for applications in nonvolatile phase-change memory devices, as its properties can be controlled by visible-light illumination. Among the several ways to synthesize MoTe2, the molybdenum oxide tellurization through isothermal close space sublimation (CSS) annealing in gas atmosphere is a simple and low-cost effective method for large-scale production of devices based on this layered material. Therefore, the understanding of the physical properties of MoTe2 thin films produced by this technique is crucial for future applications. Surprisingly, our results indicate that there is a photoinduced growth of the crystalline phase of tellurium on the 1T′-MoTe2 matrix even when the power density of the laser is low. From Raman spectroscopy investigations, we were able to show that nanometer-sized tellurium crystallites work as seed sites for the photocrystallization of tellurium. By assuming that the overall crystallization process is described by a kinetic approach that is based on the Kolmogorov–Johnson–Mehl–Avrami theory, our results indicate that the process is governed by an anisotropic organization of the tellurium atoms in helical structures during the crystal growth.
{"title":"Photoinduced growth of the crystalline phase of tellurium on a 1T′-MoTe2 matrix","authors":"Paulo Victor Sciammarella, Matheus Almeida de Souza, Luciano de Moura Guimarães, Maria Ivonete Nogueira da Silva, Juan Carlos González Pérez, Leandro Gutierrez Rizzi, Eduardo Nery Duarte Araujo","doi":"10.1063/5.0152814","DOIUrl":"https://doi.org/10.1063/5.0152814","url":null,"abstract":"Due to the growing demand for miniaturization and energy efficiency in modern electronic devices, there is a renewed interest for optoelectronic memories and sensors based on 2D materials. In particular, the molybdenum ditelluride (MoTe2) is one of the most promising materials for applications in nonvolatile phase-change memory devices, as its properties can be controlled by visible-light illumination. Among the several ways to synthesize MoTe2, the molybdenum oxide tellurization through isothermal close space sublimation (CSS) annealing in gas atmosphere is a simple and low-cost effective method for large-scale production of devices based on this layered material. Therefore, the understanding of the physical properties of MoTe2 thin films produced by this technique is crucial for future applications. Surprisingly, our results indicate that there is a photoinduced growth of the crystalline phase of tellurium on the 1T′-MoTe2 matrix even when the power density of the laser is low. From Raman spectroscopy investigations, we were able to show that nanometer-sized tellurium crystallites work as seed sites for the photocrystallization of tellurium. By assuming that the overall crystallization process is described by a kinetic approach that is based on the Kolmogorov–Johnson–Mehl–Avrami theory, our results indicate that the process is governed by an anisotropic organization of the tellurium atoms in helical structures during the crystal growth.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"1 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139409193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Many natural substances in nature exhibit magnetism, which has a significant impact on human life. However, accurately predicting, analyzing, and manipulating magnetic fields requires the use of precise mathematical simulation techniques. One such method is numerical modeling with element matrices, which is crucial for simulating and analyzing complex physical models. In conventional mesh-based modeling, there is always a residual error, and the accuracy of the solution can be greatly affected by the mesh density. This work proposed a new numerical modeling theory for the field of magnetics, which is based on specially designed points within an element. With this new computational framework, the mesh-dependence feature of the element matrix can be significantly reduced, allowing for more efficient convergence to the theoretical value with minimal differences. This method can handle a wide range of extreme physical conditions in both three-dimensional and two-dimensional scenarios, which are beyond the capabilities of conventional methods, and can provide highly accurate computational solutions. The proposed method is demonstrated through the passive shielding design of a 9.4 T whole-body magnetic resonance imaging superconducting magnet, and the concept design of an extremely weak magnetic field scientific facility with cross-scale geometry was exemplified by the proposed method.
自然界中的许多天然物质都具有磁性，这对人类生活有着重大影响。然而，准确预测、分析和操控磁场需要使用精确的数学模拟技术。其中一种方法是使用元素矩阵进行数值建模，这对于模拟和分析复杂的物理模型至关重要。在传统的基于网格的建模中，总会存在残余误差，而且网格密度会极大地影响求解的准确性。本研究针对磁学领域提出了一种新的数值建模理论，该理论基于元素内特殊设计的点。利用这种新的计算框架，可以显著降低元素矩阵的网格依赖特征，从而以最小的差异更有效地收敛到理论值。这种方法可以在三维和二维场景中处理各种极端物理条件，这超出了传统方法的能力范围，并能提供高精度的计算解决方案。该方法通过 9.4 T 全身磁共振成像超导磁体的被动屏蔽设计进行了演示，并以跨尺度几何的极弱磁场科学设施的概念设计为例进行了示范。
{"title":"Accurate magnetization modeling in multi-dimensional applications","authors":"Yaohui Wang, Wenhui Yang, Feng Liu, Qiuliang Wang","doi":"10.1063/5.0173725","DOIUrl":"https://doi.org/10.1063/5.0173725","url":null,"abstract":"Many natural substances in nature exhibit magnetism, which has a significant impact on human life. However, accurately predicting, analyzing, and manipulating magnetic fields requires the use of precise mathematical simulation techniques. One such method is numerical modeling with element matrices, which is crucial for simulating and analyzing complex physical models. In conventional mesh-based modeling, there is always a residual error, and the accuracy of the solution can be greatly affected by the mesh density. This work proposed a new numerical modeling theory for the field of magnetics, which is based on specially designed points within an element. With this new computational framework, the mesh-dependence feature of the element matrix can be significantly reduced, allowing for more efficient convergence to the theoretical value with minimal differences. This method can handle a wide range of extreme physical conditions in both three-dimensional and two-dimensional scenarios, which are beyond the capabilities of conventional methods, and can provide highly accurate computational solutions. The proposed method is demonstrated through the passive shielding design of a 9.4 T whole-body magnetic resonance imaging superconducting magnet, and the concept design of an extremely weak magnetic field scientific facility with cross-scale geometry was exemplified by the proposed method.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"81 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139409221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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