Pub Date : 2024-08-30DOI: 10.1088/1361-6463/ad6fae
Céline Ruscher, Robinson Cortes-Huerto, Robert Hannebauer, Debashish Mukherji, Alireza Nojeh, A Srikantha Phani
Using large scale molecular dynamics simulations, we study the thermal conductivity of bare and surface passivated silicon nanowires (SiNWs). For the cross–sectional widths w⩽2 nm, SiNWs become unstable because of the surface amorphization and also due to the evaporation of a certain fraction of Si atoms. The observed surface (in–)stability is related to a large excess energy Δ of the surface Si atoms with respect to the bulk Si, resulting from the surface atoms being less coordinated and having dangling bonds. We first propose a practically relevant method that uses Δ as a guiding tool to passivate these dangling bonds with hydrogen or oxygen, stabilizing the SiNWs. These passivated SiNWs are used to calculate the thermal conductivity coefficient κ. While the expected trend of κ∝w is observed for all SiNWs, surface passivation provides an added flexibility of tuning κ with the surface coverage concentration c of passivated atoms. Indeed, with respect to the bulk κ, passivation of SiNW reduces κ by 75%–80% for c→50% and increases it by 50% for the fully passivated samples. Analyzing the phonon band structures via spectral energy density, we discuss separate contributions from the surface and the core to κ. Our results also reveal that surface passivation increases SiNW stiffness, contributing to the tunability in κ.
{"title":"Tuning the thermal conductivity of silicon nanowires by surface passivation","authors":"Céline Ruscher, Robinson Cortes-Huerto, Robert Hannebauer, Debashish Mukherji, Alireza Nojeh, A Srikantha Phani","doi":"10.1088/1361-6463/ad6fae","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6fae","url":null,"abstract":"Using large scale molecular dynamics simulations, we study the thermal conductivity of bare and surface passivated silicon nanowires (SiNWs). For the cross–sectional widths <inline-formula>\u0000<tex-math><?CDATA $w unicode{x2A7D} 2$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mi>w</mml:mi><mml:mtext>⩽</mml:mtext><mml:mn>2</mml:mn></mml:mrow></mml:math><inline-graphic xlink:href=\"dad6faeieqn1.gif\"></inline-graphic></inline-formula> nm, SiNWs become unstable because of the surface amorphization and also due to the evaporation of a certain fraction of Si atoms. The observed surface (in–)stability is related to a large excess energy Δ of the surface Si atoms with respect to the bulk Si, resulting from the surface atoms being less coordinated and having dangling bonds. We first propose a practically relevant method that uses Δ as a guiding tool to passivate these dangling bonds with hydrogen or oxygen, stabilizing the SiNWs. These passivated SiNWs are used to calculate the thermal conductivity coefficient <italic toggle=\"yes\">κ</italic>. While the expected trend of <inline-formula>\u0000<tex-math><?CDATA $kappa propto w$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mi>κ</mml:mi><mml:mo>∝</mml:mo><mml:mi>w</mml:mi></mml:mrow></mml:math><inline-graphic xlink:href=\"dad6faeieqn2.gif\"></inline-graphic></inline-formula> is observed for all SiNWs, surface passivation provides an added flexibility of tuning <italic toggle=\"yes\">κ</italic> with the surface coverage concentration <italic toggle=\"yes\">c</italic> of passivated atoms. Indeed, with respect to the bulk <italic toggle=\"yes\">κ</italic>, passivation of SiNW reduces <italic toggle=\"yes\">κ</italic> by 75%–80% for <inline-formula>\u0000<tex-math><?CDATA $c to 50%$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mi>c</mml:mi><mml:mo accent=\"false\" stretchy=\"false\">→</mml:mo><mml:mn>50</mml:mn><mml:mi mathvariant=\"normal\">%</mml:mi></mml:mrow></mml:math><inline-graphic xlink:href=\"dad6faeieqn3.gif\"></inline-graphic></inline-formula> and increases it by 50% for the fully passivated samples. Analyzing the phonon band structures via spectral energy density, we discuss separate contributions from the surface and the core to <italic toggle=\"yes\">κ</italic>. Our results also reveal that surface passivation increases SiNW stiffness, contributing to the tunability in <italic toggle=\"yes\">κ</italic>.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"11 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223022","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}
Pub Date : 2024-08-29DOI: 10.1088/1361-6463/ad7148
Fengming Yang, Wencong Zhang, Kama Huang, Yang Yang, Huacheng Zhu
The microwave-to-plasma energy conversion efficiency and the ease of plasma self-ignition are critical factors affecting the applications for microwave plasma sources (MPSs). This study presents a novel MPS utilizing dielectric wedges for self-ignition and improved energy conversion. Firstly, we crafted a dielectric wedge with a gradient refractive index, guiding the electric field from air to dielectric materials and facilitating microwave propagation along the dielectric in a waveguide. Through electromagnetic simulation, we explored how the size and permittivity of the dielectric wedge affect the electric field distribution. Then, the MPS based on the dielectric wedge was designed. In this configuration, a dielectric tube encloses the discharge tube, connecting to dielectric wedges to guide electromagnetic waves to the plasma. We analyzed the MPS performance using the Drude model, evaluating microwave energy conversion efficiency across various electron densities and collision frequencies. The results were compared with a commonly used MPS based on a tapered waveguide, demonstrating the proposed MPS has wider applicability across different operation conditions. Finally, experiments under low pressures were conducted using various gases, showing an average energy conversion efficiency of approximately 40% higher than the tapered waveguide MPS. The experiments also indicate the proposed MPS has a greater capability of self-ignition at lower power levels. These findings highlight the efficacy of incorporating dielectric wedges to enhance MPS performance, making it conducive for broader industrial applications.
{"title":"A high-performance microwave plasma source employing dielectric wedges","authors":"Fengming Yang, Wencong Zhang, Kama Huang, Yang Yang, Huacheng Zhu","doi":"10.1088/1361-6463/ad7148","DOIUrl":"https://doi.org/10.1088/1361-6463/ad7148","url":null,"abstract":"The microwave-to-plasma energy conversion efficiency and the ease of plasma self-ignition are critical factors affecting the applications for microwave plasma sources (MPSs). This study presents a novel MPS utilizing dielectric wedges for self-ignition and improved energy conversion. Firstly, we crafted a dielectric wedge with a gradient refractive index, guiding the electric field from air to dielectric materials and facilitating microwave propagation along the dielectric in a waveguide. Through electromagnetic simulation, we explored how the size and permittivity of the dielectric wedge affect the electric field distribution. Then, the MPS based on the dielectric wedge was designed. In this configuration, a dielectric tube encloses the discharge tube, connecting to dielectric wedges to guide electromagnetic waves to the plasma. We analyzed the MPS performance using the Drude model, evaluating microwave energy conversion efficiency across various electron densities and collision frequencies. The results were compared with a commonly used MPS based on a tapered waveguide, demonstrating the proposed MPS has wider applicability across different operation conditions. Finally, experiments under low pressures were conducted using various gases, showing an average energy conversion efficiency of approximately 40% higher than the tapered waveguide MPS. The experiments also indicate the proposed MPS has a greater capability of self-ignition at lower power levels. These findings highlight the efficacy of incorporating dielectric wedges to enhance MPS performance, making it conducive for broader industrial applications.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"438 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223060","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}
Pub Date : 2024-08-29DOI: 10.1088/1361-6463/ad7152
Hucheng Liang, Boxue Du
Epoxy insulators in gas-insulated power apparatus are subjected to the combined effects of electrical and mechanical loads. In this work, a simulation model is built based on the energy theory to explore the electrical tree growth of epoxy resin under tensile and compressive stresses. With increasing AC voltage, the electrical tree growth is promoted, exhibiting a morphology with more branches. Tensile stress accelerates the electrical tree growth, while proper compressive stress has the opposite effect. However, when the compressive stress exceeds a certain value, electrical tree growth is promoted again. When the mechanical stress is vertical to the needle electrode, these effects primarily impact the length of the trees. Conversely, in parallel cases, mechanical stress mainly affects the width of the electrical trees. Filler doping play the role of obstacles as well as enhancing the electric field concentration, the electrical tree growth is firstly inhibited and then promoted as the doping content increases. The electrical tree morphologies of simulation and experiment are in good consistency, proving the reasonability of the simulation model.
{"title":"Simulation study on electrical tree propagation under electrical and mechanical stresses","authors":"Hucheng Liang, Boxue Du","doi":"10.1088/1361-6463/ad7152","DOIUrl":"https://doi.org/10.1088/1361-6463/ad7152","url":null,"abstract":"Epoxy insulators in gas-insulated power apparatus are subjected to the combined effects of electrical and mechanical loads. In this work, a simulation model is built based on the energy theory to explore the electrical tree growth of epoxy resin under tensile and compressive stresses. With increasing AC voltage, the electrical tree growth is promoted, exhibiting a morphology with more branches. Tensile stress accelerates the electrical tree growth, while proper compressive stress has the opposite effect. However, when the compressive stress exceeds a certain value, electrical tree growth is promoted again. When the mechanical stress is vertical to the needle electrode, these effects primarily impact the length of the trees. Conversely, in parallel cases, mechanical stress mainly affects the width of the electrical trees. Filler doping play the role of obstacles as well as enhancing the electric field concentration, the electrical tree growth is firstly inhibited and then promoted as the doping content increases. The electrical tree morphologies of simulation and experiment are in good consistency, proving the reasonability of the simulation model.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"22 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223064","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}
Aramid fiber (AF)-reinforced epoxy (EP) resin composite materials are widely used in the application of insulation rod-reinforced components, but the adhesion performance between AFs and EP resin is poor, which easily leads to interfacial defects and even gradually develops into breakdown, flashover, and other faults. In this study, a simple, environmentally friendly, diverse, and highly designable layer-by-layer self-assembly modification method was adopted to assemble aramid nanofibers/SiO2 onto the surface of AFs. The modified AFs were then used to produce composite materials with EP resin. By testing the interface breakdown, flashover, and leakage current of the AF/EP resin composite materials, the influence mechanism of AF surface modification on the material interface insulation performance was studied. The results show that the insulation performance of the modified composite material first increases and then decreases with the increase in the number of assembled layers, with the maximum increase in breakdown voltage being 93.56% and the maximum increase in flashover voltage being 30.91%.
芳纶纤维（AF）增强环氧树脂（EP）复合材料在绝缘杆增强构件中应用广泛，但AF与EP树脂之间的粘附性能较差，容易导致界面缺陷，甚至逐渐发展为击穿、闪络等故障。本研究采用一种简单、环保、多样且可设计性强的逐层自组装改性方法，将芳纶纳米纤维/二氧化硅组装到 AFs 表面。改性后的 AFs 可用于生产 EP 树脂复合材料。通过测试 AF/EP 树脂复合材料的界面击穿、闪络和泄漏电流，研究了 AF 表面改性对材料界面绝缘性能的影响机理。结果表明，随着组装层数的增加，改性复合材料的绝缘性能先升后降，击穿电压的最大升幅为 93.56%，闪络电压的最大升幅为 30.91%。
{"title":"Effect characteristics of ANFs/SiO2 layer self-assembly on the insulation properties of aramid/epoxy composites","authors":"Jun Xie, Chengming Hu, Guowei Xia, Youzhi Zhang, Longyin Qiao, Bobin Xu, Xiaoyu Shi, Qing Xie","doi":"10.1088/1361-6463/ad714d","DOIUrl":"https://doi.org/10.1088/1361-6463/ad714d","url":null,"abstract":"Aramid fiber (AF)-reinforced epoxy (EP) resin composite materials are widely used in the application of insulation rod-reinforced components, but the adhesion performance between AFs and EP resin is poor, which easily leads to interfacial defects and even gradually develops into breakdown, flashover, and other faults. In this study, a simple, environmentally friendly, diverse, and highly designable layer-by-layer self-assembly modification method was adopted to assemble aramid nanofibers/SiO<sub>2</sub> onto the surface of AFs. The modified AFs were then used to produce composite materials with EP resin. By testing the interface breakdown, flashover, and leakage current of the AF/EP resin composite materials, the influence mechanism of AF surface modification on the material interface insulation performance was studied. The results show that the insulation performance of the modified composite material first increases and then decreases with the increase in the number of assembled layers, with the maximum increase in breakdown voltage being 93.56% and the maximum increase in flashover voltage being 30.91%.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"61 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223065","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}
Pub Date : 2024-08-29DOI: 10.1088/1361-6463/ad7036
Eunjin Lim, Dahye Kim, Jongmin Park, Minsuk Koo, Sungjun Kim
The increasing demand of information and communication technology has pushed conventional computing paradigm to its limit. In addition, physical and technological factors have constrained the advancement of conventional memory devices. Considering the rapid back-and-forth transfer of a large amount of information, emerging memory should demonstrate space efficiency, fast speed, and low-cost requirements. Accordingly, ferroelectric films based on HfOx are being intensively researched owing to their high energy efficiency and compatibility with complementary metal oxide semiconductor. Particularly, owing to the simplicity of their structure, low power, and less variation, hafnia-based ferroelectric tunnel junctions (FTJs) stand out among ferroelectric memories. Numerous studies have demonstrated the improved ferroelectricity of FTJs using various engineering methods, including doping, annealing, and varying electrodes. To improve the properties of HfOx-based FTJs and enhance their applications, it is necessary to organize and discuss recent studies and prospects. Therefore, this paper reviews in-depth and comprehensive studies on FTJs and their advantages compared to other emerging devices. Additionally, in-memory computing applications, outlook, and challenges of hafnia-based FTJs are presented.
{"title":"Recent advances in the mechanism, properties, and applications of hafnia ferroelectric tunnel junctions","authors":"Eunjin Lim, Dahye Kim, Jongmin Park, Minsuk Koo, Sungjun Kim","doi":"10.1088/1361-6463/ad7036","DOIUrl":"https://doi.org/10.1088/1361-6463/ad7036","url":null,"abstract":"The increasing demand of information and communication technology has pushed conventional computing paradigm to its limit. In addition, physical and technological factors have constrained the advancement of conventional memory devices. Considering the rapid back-and-forth transfer of a large amount of information, emerging memory should demonstrate space efficiency, fast speed, and low-cost requirements. Accordingly, ferroelectric films based on HfO<italic toggle=\"yes\"><sub>x</sub></italic> are being intensively researched owing to their high energy efficiency and compatibility with complementary metal oxide semiconductor. Particularly, owing to the simplicity of their structure, low power, and less variation, hafnia-based ferroelectric tunnel junctions (FTJs) stand out among ferroelectric memories. Numerous studies have demonstrated the improved ferroelectricity of FTJs using various engineering methods, including doping, annealing, and varying electrodes. To improve the properties of HfO<italic toggle=\"yes\"><sub>x</sub></italic>-based FTJs and enhance their applications, it is necessary to organize and discuss recent studies and prospects. Therefore, this paper reviews in-depth and comprehensive studies on FTJs and their advantages compared to other emerging devices. Additionally, in-memory computing applications, outlook, and challenges of hafnia-based FTJs are presented.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"29 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223054","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}
Pub Date : 2024-08-29DOI: 10.1088/1361-6463/ad6f23
V N Androsenko, M A Kotov, N G Solovyov, A N Shemyakin, M Yu Yakimov
This paper is devoted to the experimental study of the characteristics of a continuous optical discharge (COD) sustained by high power continuous wave laser radiation at a wavelength λ = 1.08 μm in high pressure argon. New data on the COD threshold laser power dependence of argon pressure in the range 20–50 bar is obtained. The COD threshold laser power is shown to be in good agreement with the data obtained by other authors and theoretical evaluations provided the contribution of plasma energy loss due to thermal radiation is taken into account properly. The maximum plasma temperature was estimated to be 20–21 kk or higher, favorable to obtain high UV spectral radiance. A study of the convective plume oscillations around COD in argon has been carried out. It is found that in the pressure range 25–35 bars the growth of the laser radiation power leads to a decrease in convection oscillation frequency from 33 to 29 Hz, while the radius of the convective plume grows accordingly. The oscillation frequency ν and characteristic radius of the convective plume r0 were found to obey the similarity relation ν=0.5g/2r0 previously established in experiments with COD in xenon. These results are promising for using COD in argon as a high brightness broadband UV radiation source.
{"title":"Properties of a continuous optical discharge sustained by short-wave infrared laser radiation in high pressure argon","authors":"V N Androsenko, M A Kotov, N G Solovyov, A N Shemyakin, M Yu Yakimov","doi":"10.1088/1361-6463/ad6f23","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6f23","url":null,"abstract":"This paper is devoted to the experimental study of the characteristics of a continuous optical discharge (COD) sustained by high power continuous wave laser radiation at a wavelength <italic toggle=\"yes\">λ</italic> = 1.08 <italic toggle=\"yes\">μ</italic>m in high pressure argon. New data on the COD threshold laser power dependence of argon pressure in the range 20–50 bar is obtained. The COD threshold laser power is shown to be in good agreement with the data obtained by other authors and theoretical evaluations provided the contribution of plasma energy loss due to thermal radiation is taken into account properly. The maximum plasma temperature was estimated to be 20–21 kk or higher, favorable to obtain high UV spectral radiance. A study of the convective plume oscillations around COD in argon has been carried out. It is found that in the pressure range 25–35 bars the growth of the laser radiation power leads to a decrease in convection oscillation frequency from 33 to 29 Hz, while the radius of the convective plume grows accordingly. The oscillation frequency ν and characteristic radius of the convective plume <italic toggle=\"yes\">r</italic><sub>0</sub> were found to obey the similarity relation <inline-formula>\u0000<tex-math><?CDATA $nu = 0.5sqrt {{g mathord{left/ {vphantom {g {2{r_0}}}} right. } {2{r_0}}}} $?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mi>ν</mml:mi><mml:mo>=</mml:mo><mml:mn>0.5</mml:mn><mml:msqrt><mml:mrow><mml:mi>g</mml:mi><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:mrow><mml:mn>2</mml:mn><mml:mrow><mml:msub><mml:mi>r</mml:mi><mml:mn>0</mml:mn></mml:msub></mml:mrow></mml:mrow></mml:mrow></mml:msqrt></mml:mrow></mml:math><inline-graphic xlink:href=\"dad6f23ieqn1.gif\"></inline-graphic></inline-formula> previously established in experiments with COD in xenon. These results are promising for using COD in argon as a high brightness broadband UV radiation source.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"1 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223055","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}
Pub Date : 2024-08-29DOI: 10.1088/1361-6463/ad6faf
Takahiro Goya, Keiichiro Urabe, Koji Eriguchi
Recently, plasma process-induced damage (PID) has garnered significant interest in the design of thin dielectric films implemented in semiconductor devices. Silicon nitride (SiN) films, a material of interest in strain engineering, are found to suffer from PID because they are exposed to various plasmas during device manufacturing processes. Only a limited amount of experimental evidence is available at present regarding plasma-induced mechanical property changes of SiN films. In this study, we investigated the mechanical property change in SiN and SiO2 films using a cyclic nanoindentation technique. We focused on the contact stiffness (S) as the principal mechanical property parameter. Firstly, a single loading/unloading test confirmed an increase in S after Ar and He plasma exposures. Subsequently, we examined the time-dependent features of damaged SiN and SiO2 films under cyclic loading/unloading. From the cyclic test, an increase in S was seen with the number of loading/unloading cycles (N) for both SiN and SiO2 films. A larger increase in S was observed for the damaged SiN, while no significant increase was seen for the damaged SiO2 films. The observed increase in S and its time dependence are attributed to the strain developed by the created defects (e.g. interstitial species) and the reconstruction and stabilization of plasma-damaged Si–N networks with created defects, respectively. The time-dependent S analysis under cyclic loading/unloading is useful for evaluating the effects of PID on the mechanical properties of thin films.
近来，等离子体过程诱导损伤（PID）在半导体器件薄介质薄膜的设计中引起了极大的关注。氮化硅（SiN）薄膜是应变工程中的一种重要材料，由于在设备制造过程中暴露于各种等离子体中，因此会受到 PID 的影响。目前，有关等离子体诱导氮化硅薄膜机械性能变化的实验证据非常有限。在本研究中，我们使用循环纳米压痕技术研究了 SiN 和 SiO2 薄膜的机械性能变化。我们将接触刚度（S）作为主要的力学性能参数。首先，单次加载/卸载测试证实了在氩和氦等离子体暴露后 S 值的增加。随后，我们研究了在循环加载/卸载下受损的 SiN 和 SiO2 薄膜随时间变化的特征。在循环测试中，SiN 和 SiO2 薄膜的 S 值都随着加载/卸载循环次数（N）的增加而增加。在受损的 SiN 薄膜上观察到的 S 值增幅较大，而在受损的 SiO2 薄膜上则没有观察到明显的增幅。观察到的 S 值增加及其时间依赖性分别归因于产生的缺陷（如间隙物种）所产生的应变，以及等离子体损坏的 Si-N 网络与产生的缺陷的重建和稳定。在循环加载/卸载条件下进行的随时间变化的 S 分析有助于评估 PID 对薄膜机械性能的影响。
{"title":"Evaluation of plasma process-induced mechanical property change in SiN films using a cyclic nanoindentation technique","authors":"Takahiro Goya, Keiichiro Urabe, Koji Eriguchi","doi":"10.1088/1361-6463/ad6faf","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6faf","url":null,"abstract":"Recently, plasma process-induced damage (PID) has garnered significant interest in the design of thin dielectric films implemented in semiconductor devices. Silicon nitride (SiN) films, a material of interest in strain engineering, are found to suffer from PID because they are exposed to various plasmas during device manufacturing processes. Only a limited amount of experimental evidence is available at present regarding plasma-induced mechanical property changes of SiN films. In this study, we investigated the mechanical property change in SiN and SiO<sub>2</sub> films using a cyclic nanoindentation technique. We focused on the contact stiffness (<italic toggle=\"yes\">S</italic>) as the principal mechanical property parameter. Firstly, a single loading/unloading test confirmed an increase in <italic toggle=\"yes\">S</italic> after Ar and He plasma exposures. Subsequently, we examined the time-dependent features of damaged SiN and SiO<sub>2</sub> films under cyclic loading/unloading. From the cyclic test, an increase in <italic toggle=\"yes\">S</italic> was seen with the number of loading/unloading cycles (<italic toggle=\"yes\">N</italic>) for both SiN and SiO<sub>2</sub> films. A larger increase in <italic toggle=\"yes\">S</italic> was observed for the damaged SiN, while no significant increase was seen for the damaged SiO<sub>2</sub> films. The observed increase in <italic toggle=\"yes\">S</italic> and its time dependence are attributed to the strain developed by the created defects (e.g. interstitial species) and the reconstruction and stabilization of plasma-damaged Si–N networks with created defects, respectively. The time-dependent <italic toggle=\"yes\">S</italic> analysis under cyclic loading/unloading is useful for evaluating the effects of PID on the mechanical properties of thin films.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"7 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223057","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}
Pub Date : 2024-08-29DOI: 10.1088/1361-6463/ad714a
Meize Li, Yahong Liu, Xin Zhou, Lianlian Du, Peng Li, Liyun Tao, Kun Song, Zhenfei Li, Xiaopeng Zhao
Recent works exploiting photonic valley Hall effect show that large-area topological states can be realized by inserting gapless photonic crystal structures into topological interfaces, thus effectively introducing mode width degree of freedom. However, the previously reported works focus on gapless edge states. It is rare to investigate gapped edge states, especially large-area gapped edge states. In this paper, large-area gapped edge states in a valley photonic crystal heterostructure are achieved and experimentally proved. Compared with large-area gapless topological states, the present gapped edge states are more localized, which provides a more effective way to manipulate electromagnetic waves. We implement a topological energy concentrator and topological resonator cavity based on the large-area topological transmission with the gapped edge states. It is expected that our results broaden photonic systems, which can be used in topological lasing, field enhancement, and high-capacity energy transport.
{"title":"Large-area gapped edge states in a valley photonic crystal heterostructure","authors":"Meize Li, Yahong Liu, Xin Zhou, Lianlian Du, Peng Li, Liyun Tao, Kun Song, Zhenfei Li, Xiaopeng Zhao","doi":"10.1088/1361-6463/ad714a","DOIUrl":"https://doi.org/10.1088/1361-6463/ad714a","url":null,"abstract":"Recent works exploiting photonic valley Hall effect show that large-area topological states can be realized by inserting gapless photonic crystal structures into topological interfaces, thus effectively introducing mode width degree of freedom. However, the previously reported works focus on gapless edge states. It is rare to investigate gapped edge states, especially large-area gapped edge states. In this paper, large-area gapped edge states in a valley photonic crystal heterostructure are achieved and experimentally proved. Compared with large-area gapless topological states, the present gapped edge states are more localized, which provides a more effective way to manipulate electromagnetic waves. We implement a topological energy concentrator and topological resonator cavity based on the large-area topological transmission with the gapped edge states. It is expected that our results broaden photonic systems, which can be used in topological lasing, field enhancement, and high-capacity energy transport.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"12 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223061","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}
Pub Date : 2024-08-29DOI: 10.1088/1361-6463/ad7039
Nicola Roccato, Francesco Piva, Matteo Buffolo, Carlo De Santi, Nicola Trivellin, Camille Haller, Jean-François Carlin, Nicolas Grandjean, Gaudenzio Meneghesso, Enrico Zanoni, Matteo Meneghini
We investigate the degradation mechanisms of In0.2Ga0.8N/GaN light emitting diodes through combined experimental analysis and simulations. The devices were submitted to constant current stress at 100 mA. Depending on the measuring current level, two degradation trends were observed: at high test currents (e.g. 200 mA), a monotonic decrease in optical power was observed; at low test currents (e.g. 5 mA), an initial degradation was observed, followed by an improvement in device efficiency (positive ageing). For the first time, such recovery effect was analyzed and modeled, as due to the generation of charged defects at the InGaN/GaN interface, resulting in the increase in the injection efficiency at low bias levels. The role of interface defects was validated by means of numerical simulations, with good agreement with the experimental data.
{"title":"Investigation and modeling of the role of interface defects in the optical degradation of InGaN/GaN LEDs","authors":"Nicola Roccato, Francesco Piva, Matteo Buffolo, Carlo De Santi, Nicola Trivellin, Camille Haller, Jean-François Carlin, Nicolas Grandjean, Gaudenzio Meneghesso, Enrico Zanoni, Matteo Meneghini","doi":"10.1088/1361-6463/ad7039","DOIUrl":"https://doi.org/10.1088/1361-6463/ad7039","url":null,"abstract":"We investigate the degradation mechanisms of In<sub>0.2</sub>Ga<sub>0.8</sub>N/GaN light emitting diodes through combined experimental analysis and simulations. The devices were submitted to constant current stress at 100 mA. Depending on the measuring current level, two degradation trends were observed: at high test currents (e.g. 200 mA), a monotonic decrease in optical power was observed; at low test currents (e.g. 5 mA), an initial degradation was observed, followed by an improvement in device efficiency (positive ageing). For the first time, such recovery effect was analyzed and modeled, as due to the generation of charged defects at the InGaN/GaN interface, resulting in the increase in the injection efficiency at low bias levels. The role of interface defects was validated by means of numerical simulations, with good agreement with the experimental data.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"5 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223058","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}
Pub Date : 2024-08-29DOI: 10.1088/1361-6463/ad6fac
Hongsheng Zhai, Man Liu, Endong Wang, Yufang Liu
The growth mechanism of thiolate-protected gold nanoclusters (AuNCs) has been advanced, but precise crystal structure information is lacking. Recent mass spectrometry and nuclear magnetic resonance analysis experiments traced the Au24(SR)18 cluster as a non-negligible byproduct intermediate during the reaction between [Au25(SR)18]−, the flagship cluster of the remarkable nanocluster ship, and Au25(SR)19, a cluster with 25 Au atoms but featuring a completely different structure than the [Au25(SR)18]− cluster. However, the precise structure of the Au24(SR)18 cluster is unknown. In this study, a total of seven Au24(SR)18 isomers were constructed using the grand unified model. Density functional theory calculations demonstrated that two of them could be considered quasi-degenerate suggesting that both might coexist in experiments. Geometrical features, electronic structures, and absorption spectra were calculated for potential future comparisons. This work contributes to fully interpreting the growth mechanism of AuNCs .
{"title":"Rational design of the 6e thiolate-protected Au24(SR)18 nanocluster","authors":"Hongsheng Zhai, Man Liu, Endong Wang, Yufang Liu","doi":"10.1088/1361-6463/ad6fac","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6fac","url":null,"abstract":"The growth mechanism of thiolate-protected gold nanoclusters (AuNCs) has been advanced, but precise crystal structure information is lacking. Recent mass spectrometry and nuclear magnetic resonance analysis experiments traced the Au<sub>24</sub>(SR)<sub>18</sub> cluster as a non-negligible byproduct intermediate during the reaction between [Au<sub>25</sub>(SR)<sub>18</sub>]<sup>−</sup>, the flagship cluster of the remarkable nanocluster ship, and Au<sub>25</sub>(SR)<sub>19</sub>, a cluster with 25 Au atoms but featuring a completely different structure than the [Au<sub>25</sub>(SR)<sub>18</sub>]<sup>−</sup> cluster. However, the precise structure of the Au<sub>24</sub>(SR)<sub>18</sub> cluster is unknown. In this study, a total of seven Au<sub>24</sub>(SR)<sub>18</sub> isomers were constructed using the grand unified model. Density functional theory calculations demonstrated that two of them could be considered quasi-degenerate suggesting that both might coexist in experiments. Geometrical features, electronic structures, and absorption spectra were calculated for potential future comparisons. This work contributes to fully interpreting the growth mechanism of AuNCs .","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"22 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223056","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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