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}
Nanoscale vacuum channel transistors (NVCTs) have garnered considerable interest due to their outstanding high frequency characteristics and high reliability, stemming from a distinct carrier transport mechanism compared to solid-state devices. Electrons traverse the nanoscale vacuum channel through scattering-free ballistic transport. However, existing research has predominantly focused on the structural design and optimization of NVCTs, with relatively few studies delving into their high frequency performance. Hence, alongside structural exploration and optimizing, investigating the high-frequency characteristics of NVCTs assumes particular importance. In this study, a novel NVCTs with a gate-cathode height difference structure was proposed and its electrical characteristics were simulated. Simulation results reveal that the presence of gate-cathode height difference effectively enhance the DC characteristics of NVCTs. Moreover, high frequency simulation demonstrate that the proposed device can operate frequency exceeding 1 THz. Whitin the GHz and even terahertz (THz) range, NVCTs exhibits exceptional high frequency properties, including ultrafast response times and minimal distortion. These findings not only offer insights for future structural design and optimization of NVCTs but also underscore the potential of NVCTs in radio frequency and THz applications.
{"title":"High-frequency performance in nanoscale vacuum channel transistors with gate-cathode height difference","authors":"Yuezhong Chen, Xin Zhai, Congyuan Lin, Ziyang Liu, Xiaobing Zhang, Ji Xu","doi":"10.1088/1361-6463/ad70c2","DOIUrl":"https://doi.org/10.1088/1361-6463/ad70c2","url":null,"abstract":"Nanoscale vacuum channel transistors (NVCTs) have garnered considerable interest due to their outstanding high frequency characteristics and high reliability, stemming from a distinct carrier transport mechanism compared to solid-state devices. Electrons traverse the nanoscale vacuum channel through scattering-free ballistic transport. However, existing research has predominantly focused on the structural design and optimization of NVCTs, with relatively few studies delving into their high frequency performance. Hence, alongside structural exploration and optimizing, investigating the high-frequency characteristics of NVCTs assumes particular importance. In this study, a novel NVCTs with a gate-cathode height difference structure was proposed and its electrical characteristics were simulated. Simulation results reveal that the presence of gate-cathode height difference effectively enhance the DC characteristics of NVCTs. Moreover, high frequency simulation demonstrate that the proposed device can operate frequency exceeding 1 THz. Whitin the GHz and even terahertz (THz) range, NVCTs exhibits exceptional high frequency properties, including ultrafast response times and minimal distortion. These findings not only offer insights for future structural design and optimization of NVCTs but also underscore the potential of NVCTs in radio frequency and THz applications.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"4 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223059","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/ad7151
Shimin Yu, Zili Chen, Jingwen Xu, Hongyu Wang, Lu Wang, Zhijiang Wang, Wei Jiang, Julian Schulze, Ya Zhang
Capacitively coupled plasmas (CCPs) are widely used in plasma processing applications, where efficient power coupling between the radio frequency (RF) source and the plasma is crucial. In practical CCP systems, impedance matching networks (IMNs) are employed to minimize power reflection. However, the presence of coaxial cables can significantly impact plasma impedance and matching performance. We develop a comprehensive simulation framework for the IMN design of CCPs, fully considering the effects of RF coaxial cables. The model self-consistently couples a distributed transmission line (TL) model, a lumped-element circuit model, and an electrostatic particle-in-cell model. This coupled model is used to investigate the impact of coaxial cables on matching performance under various discharge conditions and cable configurations. The simulation results indicate that the optimal power transmission efficiency was achieved after 6 matching iterations. The power coupled to the CCP increased from 2.7 W before matching to 180.9 W, and the reflection coefficient ultimately decreased to 0.003. The results also reveal that neglecting the cables will lead to a decrease in the power dissipated in the CCP. The proposed method demonstrates effectiveness in achieving impedance matching for different gas pressures (75–300 mTorr) and cable lengths. It can be concluded that the matching speed is faster for an appropriate cable length. This work provides valuable insights into the role of TLs in CCP impedance matching and offers a practical tool for optimizing power delivery in realistic CCP systems with RF coaxial cables.
{"title":"Impedance matching design for capacitively coupled plasmas considering coaxial cables","authors":"Shimin Yu, Zili Chen, Jingwen Xu, Hongyu Wang, Lu Wang, Zhijiang Wang, Wei Jiang, Julian Schulze, Ya Zhang","doi":"10.1088/1361-6463/ad7151","DOIUrl":"https://doi.org/10.1088/1361-6463/ad7151","url":null,"abstract":"Capacitively coupled plasmas (CCPs) are widely used in plasma processing applications, where efficient power coupling between the radio frequency (RF) source and the plasma is crucial. In practical CCP systems, impedance matching networks (IMNs) are employed to minimize power reflection. However, the presence of coaxial cables can significantly impact plasma impedance and matching performance. We develop a comprehensive simulation framework for the IMN design of CCPs, fully considering the effects of RF coaxial cables. The model self-consistently couples a distributed transmission line (TL) model, a lumped-element circuit model, and an electrostatic particle-in-cell model. This coupled model is used to investigate the impact of coaxial cables on matching performance under various discharge conditions and cable configurations. The simulation results indicate that the optimal power transmission efficiency was achieved after 6 matching iterations. The power coupled to the CCP increased from 2.7 W before matching to 180.9 W, and the reflection coefficient ultimately decreased to 0.003. The results also reveal that neglecting the cables will lead to a decrease in the power dissipated in the CCP. The proposed method demonstrates effectiveness in achieving impedance matching for different gas pressures (75–300 mTorr) and cable lengths. It can be concluded that the matching speed is faster for an appropriate cable length. This work provides valuable insights into the role of TLs in CCP impedance matching and offers a practical tool for optimizing power delivery in realistic CCP systems with RF coaxial cables.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"13 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223062","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 : 2024-08-08DOI: 10.1088/1361-6463/ad6a25
Liu Liu, Anding Li, Yukun Chen, Ruirui Liu, Jiayue Xu, Jiwei Zhai, Zhitang Song and Sannian Song
This study investigates the phase-change properties of [Ge8Sb92 (25 nm)-Ge2Sb2Te5 (25 nm)]1 multilayer thin films, elucidating three distinct resistance states originating from two structural transitions: initial Sb precipitation and Ge2Sb2Te5-FCC crystallization, followed by Ge2Sb2Te5-FCC to Ge2Sb2Te5-HEX transformation with additional Sb precipitation. The phase transitions induce two abrupt changes in resistance at temperatures of 169.8 °C and 197.7 °C, respectively, with corresponding data retention temperatures of 97 °C and 129 °C, indicating robust thermal stability. The [Ge8Sb92 (25 nm)-Ge2Sb2Te5 (25 nm)]1-based phase change random access memory (PCRAM) device demonstrates reversible switching characteristics and multi-level storage capabilities within 20 ns, showcasing enhanced phase-change speed and storage density. In summary, [Ge8Sb92(25 nm)-Ge2Sb2Te5(25 nm)]1 demonstrates enhanced thermal stability, swift phase transition, and increased storage density relative to conventional Ge2Sb2Te5, establishing it as a promising new phase-change material for PCRAM applications.
{"title":"Multilayer Ge8Sb92/Ge2Sb2Te5 thin films: unveiling distinct resistance states and enhanced performance for phase change random access memory","authors":"Liu Liu, Anding Li, Yukun Chen, Ruirui Liu, Jiayue Xu, Jiwei Zhai, Zhitang Song and Sannian Song","doi":"10.1088/1361-6463/ad6a25","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6a25","url":null,"abstract":"This study investigates the phase-change properties of [Ge8Sb92 (25 nm)-Ge2Sb2Te5 (25 nm)]1 multilayer thin films, elucidating three distinct resistance states originating from two structural transitions: initial Sb precipitation and Ge2Sb2Te5-FCC crystallization, followed by Ge2Sb2Te5-FCC to Ge2Sb2Te5-HEX transformation with additional Sb precipitation. The phase transitions induce two abrupt changes in resistance at temperatures of 169.8 °C and 197.7 °C, respectively, with corresponding data retention temperatures of 97 °C and 129 °C, indicating robust thermal stability. The [Ge8Sb92 (25 nm)-Ge2Sb2Te5 (25 nm)]1-based phase change random access memory (PCRAM) device demonstrates reversible switching characteristics and multi-level storage capabilities within 20 ns, showcasing enhanced phase-change speed and storage density. In summary, [Ge8Sb92(25 nm)-Ge2Sb2Te5(25 nm)]1 demonstrates enhanced thermal stability, swift phase transition, and increased storage density relative to conventional Ge2Sb2Te5, establishing it as a promising new phase-change material for PCRAM applications.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"61 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943603","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 : 2024-08-08DOI: 10.1088/1361-6463/ad6a23
Na Xiao, Vishal Khandelwal, Saravanan Yuvaraja, Dhanu Chettri, Genesh Mainali, Zhiyuan Liu, Mohamed Ben Hassine, Xiao Tang and Xiaohang Li
Here, we demonstrate a high-mobility indium oxide (In2O3) thin-film transistor (TFT) with a sputtered alumina (Al2O3) passivation layer (PVL) with a low thermal budget (200 °C). The sputtering process of the Al2O3 PVL plays a positive role in improving the field-effect mobility (µFE) and current on/off ratio (ION/IOFF) performance of the In2O3 TFTs. However, these enhancements are limited due to the high density of intrinsic trap defects in the In2O3 channels, as reflected in their large hysteresis and poor bias stability. Treating the In2O3 channel with oxygen (O2) plasma prior to sputtering the Al2O3 PVL results in notable improvements. Specifically, a high µFE of 128.3 cm2V−1 s−1, a high ION/IOFF over 106 at VDS of 0.1 V, a small hysteresis of 0.03 V, and a negligible threshold voltage shift under negative bias stress are achieved in the passivated In2O3 TFT (with O2 plasma pretreatment), representing a significant improvement compared to the passivated In2O3 TFT (without O2 plasma pretreatment) and the unpassivated In2O3 TFT. The remarkable reduction of intrinsic trap defects in the passivated In2O3 TFT compensated by O2 plasma is the primary mechanism underlying the improvement in µFE and bias stability, as validated by x-ray photoelectron spectra, hysteresis analysis, and temperature-stress electrical characterizations. Plasma treatment effectively compensates for intrinsic trap defects in oxide semiconductor (OS) channels, when combined with sputter passivation, resulting in a significant enhancement of the overall performance of OS TFTs under low thermal budgets. This approach offers valuable insights into advancing OS TFTs with satisfactory driving capability and wide applicability.
{"title":"Passivated indium oxide thin-film transistors with high field-effect mobility (128.3 cm2 V−1 s−1) and low thermal budget (200 °C)","authors":"Na Xiao, Vishal Khandelwal, Saravanan Yuvaraja, Dhanu Chettri, Genesh Mainali, Zhiyuan Liu, Mohamed Ben Hassine, Xiao Tang and Xiaohang Li","doi":"10.1088/1361-6463/ad6a23","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6a23","url":null,"abstract":"Here, we demonstrate a high-mobility indium oxide (In2O3) thin-film transistor (TFT) with a sputtered alumina (Al2O3) passivation layer (PVL) with a low thermal budget (200 °C). The sputtering process of the Al2O3 PVL plays a positive role in improving the field-effect mobility (µFE) and current on/off ratio (ION/IOFF) performance of the In2O3 TFTs. However, these enhancements are limited due to the high density of intrinsic trap defects in the In2O3 channels, as reflected in their large hysteresis and poor bias stability. Treating the In2O3 channel with oxygen (O2) plasma prior to sputtering the Al2O3 PVL results in notable improvements. Specifically, a high µFE of 128.3 cm2V−1 s−1, a high ION/IOFF over 106 at VDS of 0.1 V, a small hysteresis of 0.03 V, and a negligible threshold voltage shift under negative bias stress are achieved in the passivated In2O3 TFT (with O2 plasma pretreatment), representing a significant improvement compared to the passivated In2O3 TFT (without O2 plasma pretreatment) and the unpassivated In2O3 TFT. The remarkable reduction of intrinsic trap defects in the passivated In2O3 TFT compensated by O2 plasma is the primary mechanism underlying the improvement in µFE and bias stability, as validated by x-ray photoelectron spectra, hysteresis analysis, and temperature-stress electrical characterizations. Plasma treatment effectively compensates for intrinsic trap defects in oxide semiconductor (OS) channels, when combined with sputter passivation, resulting in a significant enhancement of the overall performance of OS TFTs under low thermal budgets. This approach offers valuable insights into advancing OS TFTs with satisfactory driving capability and wide applicability.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"25 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943602","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 : 2024-08-08DOI: 10.1088/1361-6463/ad6a24
Longxin Wan, Xiaofei Xu, Kun Duan and Junming Zhao
A broadband optically transparent metasurface microwave absorber (MMA) is designed and experimentally studied. The MMA is made of two indium tin oxide (ITO) resistive films deposited on two transparent polyethylene terephthalate substrates respectively, between which is sandwiched a single air spacer. The top ITO resistive film is etched with periodic interdigital metasurface patterns in rotational symmetry, while the bottom ITO resistive film is an integrated sheet with a low resistance working as the backplane. By carefully optimizing the functional interdigital metasurface structures in a numerical solver, a desirable 4-octave broadband MMA is achieved. The absorbing bandwidth is 4.53–18.71 GHz (122.03%) in the numerical predictions for the perpendicular incidence, in which the absorptivity is greater than 90%. Its total thickness is only 5.8 mm or 0.088λL, where λL is the wavelength (66.23 mm) at the lowest 4.53 GHz. The absorber is validated in experiments. Results are observed in good agreement with the simulated ones. The interdigital MMA is polarization-insensitive and able to operate for wide-angle incidences up to 45°. These properties are demonstrated in both simulations and experiments.
{"title":"Broadband optically transparent microwave absorber made of interdigital metasurfaces in rotational symmetry with a single air spacer","authors":"Longxin Wan, Xiaofei Xu, Kun Duan and Junming Zhao","doi":"10.1088/1361-6463/ad6a24","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6a24","url":null,"abstract":"A broadband optically transparent metasurface microwave absorber (MMA) is designed and experimentally studied. The MMA is made of two indium tin oxide (ITO) resistive films deposited on two transparent polyethylene terephthalate substrates respectively, between which is sandwiched a single air spacer. The top ITO resistive film is etched with periodic interdigital metasurface patterns in rotational symmetry, while the bottom ITO resistive film is an integrated sheet with a low resistance working as the backplane. By carefully optimizing the functional interdigital metasurface structures in a numerical solver, a desirable 4-octave broadband MMA is achieved. The absorbing bandwidth is 4.53–18.71 GHz (122.03%) in the numerical predictions for the perpendicular incidence, in which the absorptivity is greater than 90%. Its total thickness is only 5.8 mm or 0.088λL, where λL is the wavelength (66.23 mm) at the lowest 4.53 GHz. The absorber is validated in experiments. Results are observed in good agreement with the simulated ones. The interdigital MMA is polarization-insensitive and able to operate for wide-angle incidences up to 45°. These properties are demonstrated in both simulations and experiments.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"56 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943600","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 : 2024-08-08DOI: 10.1088/1361-6463/ad6a21
Xiao Zhang, Tian Xia, Yahui Zhang, Yikun Yang and Bintang Yang
This paper presents a novel non-contact spatial gap distance sensing (GDS) method that can provide distance information in spatial separation conditions. In many applications, such as enclosed environments, it could not provide the desired measurement of gap distance of internal non-magnetic medium due to the constraints of physical barriers and poor accessibility. Therefore, a non-invasive sensing system is designed to measure spatial gap distance for non-magnetic medium. The developed sensor system consists of a pair of heteropolar permanent magnets (PMs), a non-magnetic medium, a magnetostrictive-piezoelectric composite unit and an external space, which has the function of spatial separation measurement. By exploiting the magnetoelectric effect, the magneto-machine-electric conversion is achieved by sensing the spatial magnetic field generated by the heteropolar PMs. The coupling modeling, analysis and calibration of sensing system are conducted, and the system prototype is designed and manufactured. Additionally, the performances of the GDS are experimentally validated. Static gap distance (plate thickness) measurements of the plate and variable gap distance (instant water height) measurements of water are performed, and resolution, vibration, and drift tests are carried out. The results show the accuracy and stability of non-contact spatial gap distance detection for non-magnetic medium, highlighting its potential in various applications.
{"title":"Gap distance sensing for non-magnetic medium based on magnetoelectric effect under spatial separation condition","authors":"Xiao Zhang, Tian Xia, Yahui Zhang, Yikun Yang and Bintang Yang","doi":"10.1088/1361-6463/ad6a21","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6a21","url":null,"abstract":"This paper presents a novel non-contact spatial gap distance sensing (GDS) method that can provide distance information in spatial separation conditions. In many applications, such as enclosed environments, it could not provide the desired measurement of gap distance of internal non-magnetic medium due to the constraints of physical barriers and poor accessibility. Therefore, a non-invasive sensing system is designed to measure spatial gap distance for non-magnetic medium. The developed sensor system consists of a pair of heteropolar permanent magnets (PMs), a non-magnetic medium, a magnetostrictive-piezoelectric composite unit and an external space, which has the function of spatial separation measurement. By exploiting the magnetoelectric effect, the magneto-machine-electric conversion is achieved by sensing the spatial magnetic field generated by the heteropolar PMs. The coupling modeling, analysis and calibration of sensing system are conducted, and the system prototype is designed and manufactured. Additionally, the performances of the GDS are experimentally validated. Static gap distance (plate thickness) measurements of the plate and variable gap distance (instant water height) measurements of water are performed, and resolution, vibration, and drift tests are carried out. The results show the accuracy and stability of non-contact spatial gap distance detection for non-magnetic medium, highlighting its potential in various applications.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"18 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943597","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 : 2024-08-08DOI: 10.1088/1361-6463/ad6878
Kyunho Kim, Cheolwoo Bong and Moon Soo Bak
Laser absorption measurements were conducted on a high-density, laser-induced plasma produced in atmospheric-pressure air to investigate the spatiotemporal evolution of its electron number density. Measurements taken both along and perpendicular to the plasma’s symmetric axis showed that, upon formation, the plasma propagates in the direction opposite to the laser beam used for plasma generation, while expanding rapidly radially. The spatiotemporal evolution of the electron density was further analyzed from the measurements taken perpendicular to the plasma’s symmetric axis through tomographic reconstruction. Notably, the reconstruction was achieved using a genetic algorithm, as a probe laser beam used for absorption measurement is non-negligible in size compared to the plasma. Importantly, our measurements could reveal that the electron density reaches 4.99 × 1019 cm−3 immediately after the plasma formation at the center; moreover, there is a development of a pressure wave with high electron density, propagating outward radially due to the rapid expansion of the produced plasma.
{"title":"Spatiotemporal measurement of electron number density in high density laser-induced plasmas using laser absorption","authors":"Kyunho Kim, Cheolwoo Bong and Moon Soo Bak","doi":"10.1088/1361-6463/ad6878","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6878","url":null,"abstract":"Laser absorption measurements were conducted on a high-density, laser-induced plasma produced in atmospheric-pressure air to investigate the spatiotemporal evolution of its electron number density. Measurements taken both along and perpendicular to the plasma’s symmetric axis showed that, upon formation, the plasma propagates in the direction opposite to the laser beam used for plasma generation, while expanding rapidly radially. The spatiotemporal evolution of the electron density was further analyzed from the measurements taken perpendicular to the plasma’s symmetric axis through tomographic reconstruction. Notably, the reconstruction was achieved using a genetic algorithm, as a probe laser beam used for absorption measurement is non-negligible in size compared to the plasma. Importantly, our measurements could reveal that the electron density reaches 4.99 × 1019 cm−3 immediately after the plasma formation at the center; moreover, there is a development of a pressure wave with high electron density, propagating outward radially due to the rapid expansion of the produced plasma.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"6 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943596","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 : 2024-08-08DOI: 10.1088/1361-6463/ad6999
Anand Pandey, Tarun Kumar, Arnab Mondal and Ankush Bag
Carrier selective contacts are a primary requirement for fabricating silicon heterojunction solar cells (SHSCs). TiO2 is a prominent carrier selective contact in SHSCs owing to its excellent optoelectronic features such as suitable band offset, work function, and cost-effectiveness. Herein, we fabricated simple SHSCs in an Al/TiO2/p-Si/Ti/Au device configuration. Ultrathin 3 nm TiO2 layers were deposited onto a p-type silicon substrate using the atomic layer deposition method. The deposition temperature of TiO2 layers varied from 100 °C to 250 °C. X-ray photoelectron spectroscopic studies suggest that deposition temperature highly affects the chemical states of TiO2 and reduces the formation of defective state densities at the Fermi energy. The optical band gap values of TiO2 layers are also altered from 3.13 eV to 3.27 eV when the deposition temperature increases. The work function tuning from −5.13 eV to −4.83 eV has also been observed in TiO2 layers, suggesting the variation in Fermi level tuning, which arises due to changes in carrier concentrations at higher temperatures. Several device parameters, such as ideality factor, trap density, reverse saturation current density, barrier height, etc, have been quantified to comprehend the effects of deposition temperature on photovoltaic device performance. The results suggest that the deposition temperature significantly influences the charge transport and device performance. At an optimum temperature, a significant reduction in charge carrier recombination and trap state density has been observed, which helps to improve power conversion efficiency.
载流子选择性触点是制造硅异质结太阳能电池（SHSCs）的首要条件。二氧化钛具有良好的光电特性，如合适的带偏移、功函数和成本效益，因此在异质结太阳能电池中是一种重要的载流子选择性触点。在此，我们采用 Al/TiO2/p-Si/Ti/Au 器件配置制造了简单的 SHSC。利用原子层沉积法在 p 型硅衬底上沉积了 3 nm 的超薄 TiO2 层。TiO2 层的沉积温度从 100 °C 到 250 °C 不等。X 射线光电子能谱研究表明，沉积温度对二氧化钛的化学态有很大影响，并降低了费米能处缺陷态密度的形成。当沉积温度升高时，TiO2 层的光带隙值也从 3.13 eV 变为 3.27 eV。在二氧化钛层中还观察到工作函数从-5.13 eV调谐到-4.83 eV，这表明费米级调谐的变化是由于在较高温度下载流子浓度的变化引起的。为了理解沉积温度对光伏器件性能的影响，我们对ideality factor、阱密度、反向饱和电流密度、势垒高度等器件参数进行了量化。结果表明，沉积温度对电荷传输和器件性能有重大影响。在最佳温度下，电荷载流子重组和阱态密度显著降低，有助于提高功率转换效率。
{"title":"Optimizing charge transport and band-offset in silicon heterojunction solar cells: impact of TiO2 contact deposition temperature","authors":"Anand Pandey, Tarun Kumar, Arnab Mondal and Ankush Bag","doi":"10.1088/1361-6463/ad6999","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6999","url":null,"abstract":"Carrier selective contacts are a primary requirement for fabricating silicon heterojunction solar cells (SHSCs). TiO2 is a prominent carrier selective contact in SHSCs owing to its excellent optoelectronic features such as suitable band offset, work function, and cost-effectiveness. Herein, we fabricated simple SHSCs in an Al/TiO2/p-Si/Ti/Au device configuration. Ultrathin 3 nm TiO2 layers were deposited onto a p-type silicon substrate using the atomic layer deposition method. The deposition temperature of TiO2 layers varied from 100 °C to 250 °C. X-ray photoelectron spectroscopic studies suggest that deposition temperature highly affects the chemical states of TiO2 and reduces the formation of defective state densities at the Fermi energy. The optical band gap values of TiO2 layers are also altered from 3.13 eV to 3.27 eV when the deposition temperature increases. The work function tuning from −5.13 eV to −4.83 eV has also been observed in TiO2 layers, suggesting the variation in Fermi level tuning, which arises due to changes in carrier concentrations at higher temperatures. Several device parameters, such as ideality factor, trap density, reverse saturation current density, barrier height, etc, have been quantified to comprehend the effects of deposition temperature on photovoltaic device performance. The results suggest that the deposition temperature significantly influences the charge transport and device performance. At an optimum temperature, a significant reduction in charge carrier recombination and trap state density has been observed, which helps to improve power conversion efficiency.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"23 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943598","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 : 2024-08-08DOI: 10.1088/1361-6463/ad6a22
Chaimae Babori, Mahmoud Barati, Valentin Segouin, Romain Corcolle and Laurent Daniel
This study investigates anhysteretic strains in PZT ceramics. The anhysteretic curves are associated with a stable balanced state of polarization in the domain structure, excluding dissipative effects related to mechanisms such as domain wall pinning. Anhysteretic measurements are representative of an -ideal- scenario in which the material would undergo no energy loss due to dissipative processes, focusing on the stable and reversible aspects of the domain configuration. The different methodologies employed to measure deformations under electromechanical loading are presented, leading to the introduction of digital image correlation (DIC) as the chosen technique, recognized for its ability to capture detailed information on transverse and longitudinal strain. The article then describes a procedure developed to obtain anhysteretic strain and anhysteretic polarisation for different levels of compressive loadings. The subsequent presentation of the results of the transverse and longitudinal strain analyses provides valuable insights into the reversible and irreversible behavior of the material. They can be used as a basis for the thermodynamical modelling approaches grounded on separating reversible and irreversible contributions or as a validation of existing models describing anhysteretic behavior. The compressive stress affects both the shape of hysteretic and anhysteretic curves. The anhysteretic curve represents a stable equilibrium in the domain structure. Compressive stress reduces strain by affecting the pinning of domain walls. These points justify the interest in studying the effect of compressive stress on the anhysteretic behavior of ferroelectrics.
{"title":"Anhysteretic strains in ferroelectric ceramics under electromechanical loading","authors":"Chaimae Babori, Mahmoud Barati, Valentin Segouin, Romain Corcolle and Laurent Daniel","doi":"10.1088/1361-6463/ad6a22","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6a22","url":null,"abstract":"This study investigates anhysteretic strains in PZT ceramics. The anhysteretic curves are associated with a stable balanced state of polarization in the domain structure, excluding dissipative effects related to mechanisms such as domain wall pinning. Anhysteretic measurements are representative of an -ideal- scenario in which the material would undergo no energy loss due to dissipative processes, focusing on the stable and reversible aspects of the domain configuration. The different methodologies employed to measure deformations under electromechanical loading are presented, leading to the introduction of digital image correlation (DIC) as the chosen technique, recognized for its ability to capture detailed information on transverse and longitudinal strain. The article then describes a procedure developed to obtain anhysteretic strain and anhysteretic polarisation for different levels of compressive loadings. The subsequent presentation of the results of the transverse and longitudinal strain analyses provides valuable insights into the reversible and irreversible behavior of the material. They can be used as a basis for the thermodynamical modelling approaches grounded on separating reversible and irreversible contributions or as a validation of existing models describing anhysteretic behavior. The compressive stress affects both the shape of hysteretic and anhysteretic curves. The anhysteretic curve represents a stable equilibrium in the domain structure. Compressive stress reduces strain by affecting the pinning of domain walls. These points justify the interest in studying the effect of compressive stress on the anhysteretic behavior of ferroelectrics.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"34 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943599","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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