R. Gu, R. Xu, F. Delodovici, B. Carcan, M. Khiari, G. Vaudel, V. Juvé, M. C. Weber, A. Poirier, P. Nandi, B. Xu, V. E. Gusev, L. Bellaiche, C. Laulhé, N. Jaouen, P. Manuel, B. Dkhil, C. Paillard, L. Yedra, H. Bouyanfif, P. Ruello
Superlattices are materials created by the alternating growth of two chemically different materials. The direct consequence of creating a superlattice is the folding of the Brillouin zone, which gives rise to additional electronic bands and phonon modes. This phenomenon has been successfully exploited to achieve new transport and optical properties in semiconductor superlattices. Here, we show that multiferroic BiFeO3/LaFeO3 superlattices exhibit several structural orders parallel and perpendicular to the growth direction, not existing in individual bulk materials. Using transmission electron microscopy, x-ray diffraction, and first-principles calculations, we reveal in particular a new long-range order of tilted FeO6 octahedra, with a period along the growth direction about twice that of the chemical supercell, i.e., a superorder. The effect of this new structural order on the phonon dynamics is studied with ultrafast optical pump-probe experiments. While a folded-mode at 1.2 THz is attributed solely to the chemical modulation of the superlattice, the existence of another 0.7 THz mode seems to be explained only by a double Brillouin zone folding in agreement with the structural out-of-plane superorder. Our work shows that multiferroic BiFeO3/LaFeO3 superlattices can be used to tune the spectrum of coherent THz phonons, and potentially that of magnons or electromagnons.
{"title":"Superorders and terahertz acoustic modes in multiferroic BiFeO3/LaFeO3 superlattices","authors":"R. Gu, R. Xu, F. Delodovici, B. Carcan, M. Khiari, G. Vaudel, V. Juvé, M. C. Weber, A. Poirier, P. Nandi, B. Xu, V. E. Gusev, L. Bellaiche, C. Laulhé, N. Jaouen, P. Manuel, B. Dkhil, C. Paillard, L. Yedra, H. Bouyanfif, P. Ruello","doi":"10.1063/5.0203076","DOIUrl":"https://doi.org/10.1063/5.0203076","url":null,"abstract":"Superlattices are materials created by the alternating growth of two chemically different materials. The direct consequence of creating a superlattice is the folding of the Brillouin zone, which gives rise to additional electronic bands and phonon modes. This phenomenon has been successfully exploited to achieve new transport and optical properties in semiconductor superlattices. Here, we show that multiferroic BiFeO3/LaFeO3 superlattices exhibit several structural orders parallel and perpendicular to the growth direction, not existing in individual bulk materials. Using transmission electron microscopy, x-ray diffraction, and first-principles calculations, we reveal in particular a new long-range order of tilted FeO6 octahedra, with a period along the growth direction about twice that of the chemical supercell, i.e., a superorder. The effect of this new structural order on the phonon dynamics is studied with ultrafast optical pump-probe experiments. While a folded-mode at 1.2 THz is attributed solely to the chemical modulation of the superlattice, the existence of another 0.7 THz mode seems to be explained only by a double Brillouin zone folding in agreement with the structural out-of-plane superorder. Our work shows that multiferroic BiFeO3/LaFeO3 superlattices can be used to tune the spectrum of coherent THz phonons, and potentially that of magnons or electromagnons.","PeriodicalId":8200,"journal":{"name":"Applied physics reviews","volume":"43 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Mohammad Ubaid, Paribesh Acharyya, Suneet K. Maharana, Kanishka Biswas, Koushik Pal
Reduction of phonon mediated thermal transport properties, i.e., lattice thermal conductivity (κL), of semiconductors can strongly affect the performance of thermoelectrics and optoelectronics. Although extrinsic routes to reduce κL have been achieved through selective scattering of phonons via doping, alloying, and hierarchical nano-structuring, semiconductors with intrinsically low κL have recently gained widespread attention due to their ability to decouple electronic and phonon transports. While innate low κL in crystalline semiconductors is a desired requirement to achieve high performance thermoelectrics, the solar upconversion efficiency of photovoltaics based on metal halide perovskites (MHPs) have been shown to increase due to their ultralow κL through the hot-phonon bottleneck effect. Therefore, understanding the microscopic mechanisms underlying ultralow κL in crystalline semiconductors is extremely important. Several structural factors that are intrinsic to a material have been shown to strongly influence the reduction of κL. Among them, the presence of rattling atoms, lone-pair electrons, and large lattice anharmonicity have been widely studied. Here, we bring out yet another largely unexplored intrinsic characteristic of materials related to the filled antibonding valence states (AVS) near the Fermi level, which are shown to induce low κL in crystalline compounds. We focus our review on an emerging class of compounds–metal halide semiconductors including MHPs and investigate the interplay between structures, chemical bonding and κL, carefully curating from literature a list of 33 compounds having different structure dimensionality with known κL. We established a universal connection between the elastic moduli, speeds of sound, and κL with the presence of AVS just below the Fermi level. We found that large peak in the AVS correlates positively with lower values of elastic moduli, speeds of sound, and κL, providing antibonding states based design criteria of low-κL compounds. Furthermore, we discuss different synthesis strategies, which are crucial for experimental realization of ultralow κL through structure manipulation. Additionally, we outline how chemical bonding data can be utilized in machine learning models for predictive modeling of κL. We hope that our approach of understanding low-κL through the viewpoint of chemical bonding theory would encourage exploration of phonon transport properties in other families of materials having filled AVS that can provide further insights on the structure-bonding-property relationships aiding novel materials design approaches.
{"title":"Antibonding valence states induce low lattice thermal conductivity in metal halide semiconductors","authors":"Mohammad Ubaid, Paribesh Acharyya, Suneet K. Maharana, Kanishka Biswas, Koushik Pal","doi":"10.1063/5.0227080","DOIUrl":"https://doi.org/10.1063/5.0227080","url":null,"abstract":"Reduction of phonon mediated thermal transport properties, i.e., lattice thermal conductivity (κL), of semiconductors can strongly affect the performance of thermoelectrics and optoelectronics. Although extrinsic routes to reduce κL have been achieved through selective scattering of phonons via doping, alloying, and hierarchical nano-structuring, semiconductors with intrinsically low κL have recently gained widespread attention due to their ability to decouple electronic and phonon transports. While innate low κL in crystalline semiconductors is a desired requirement to achieve high performance thermoelectrics, the solar upconversion efficiency of photovoltaics based on metal halide perovskites (MHPs) have been shown to increase due to their ultralow κL through the hot-phonon bottleneck effect. Therefore, understanding the microscopic mechanisms underlying ultralow κL in crystalline semiconductors is extremely important. Several structural factors that are intrinsic to a material have been shown to strongly influence the reduction of κL. Among them, the presence of rattling atoms, lone-pair electrons, and large lattice anharmonicity have been widely studied. Here, we bring out yet another largely unexplored intrinsic characteristic of materials related to the filled antibonding valence states (AVS) near the Fermi level, which are shown to induce low κL in crystalline compounds. We focus our review on an emerging class of compounds–metal halide semiconductors including MHPs and investigate the interplay between structures, chemical bonding and κL, carefully curating from literature a list of 33 compounds having different structure dimensionality with known κL. We established a universal connection between the elastic moduli, speeds of sound, and κL with the presence of AVS just below the Fermi level. We found that large peak in the AVS correlates positively with lower values of elastic moduli, speeds of sound, and κL, providing antibonding states based design criteria of low-κL compounds. Furthermore, we discuss different synthesis strategies, which are crucial for experimental realization of ultralow κL through structure manipulation. Additionally, we outline how chemical bonding data can be utilized in machine learning models for predictive modeling of κL. We hope that our approach of understanding low-κL through the viewpoint of chemical bonding theory would encourage exploration of phonon transport properties in other families of materials having filled AVS that can provide further insights on the structure-bonding-property relationships aiding novel materials design approaches.","PeriodicalId":8200,"journal":{"name":"Applied physics reviews","volume":"35 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142536717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Haixin Zhang, Yunxuan Zhu, Ping Duan, Mehrdad Shiri, Sai Chandra Yelishala, Shaocheng Shen, Ziqi Song, Chuancheng Jia, Xuefeng Guo, Longji Cui, Kun Wang
Molecular-scale junctions (MSJs) have been considered the ideal testbed for probing physical and chemical processes at the molecular scale. Due to nanometric confinement, charge and energy transport in MSJs are governed by quantum mechanically dictated energy profiles, which can be tuned chemically or physically with atomic precision, offering rich possibilities beyond conventional semiconductor devices. While charge transport in MSJs has been extensively studied over the past two decades, understanding energy conversion and transport in MSJs has only become experimentally attainable in recent years. As demonstrated recently, by tuning the quantum interplay between the electrodes, the molecular core, and the contact interfaces, energy processes can be manipulated to achieve desired functionalities, opening new avenues for molecular electronics, energy harvesting, and sensing applications. This Review provides a comprehensive overview and critical analysis of various forms of energy conversion and transport processes in MSJs and their associated applications. We elaborate on energy-related processes mediated by the interaction between the core molecular structure in MSJs and different external stimuli, such as light, heat, electric field, magnetic field, force, and other environmental cues. Key topics covered include photovoltaics, electroluminescence, thermoelectricity, heat conduction, catalysis, spin-mediated phenomena, and vibrational effects. The review concludes with a discussion of existing challenges and future opportunities, aiming to facilitate in-depth future investigation of promising experimental platforms, molecular design principles, control strategies, and new application scenarios.
{"title":"Energy conversion and transport in molecular-scale junctions","authors":"Haixin Zhang, Yunxuan Zhu, Ping Duan, Mehrdad Shiri, Sai Chandra Yelishala, Shaocheng Shen, Ziqi Song, Chuancheng Jia, Xuefeng Guo, Longji Cui, Kun Wang","doi":"10.1063/5.0225756","DOIUrl":"https://doi.org/10.1063/5.0225756","url":null,"abstract":"Molecular-scale junctions (MSJs) have been considered the ideal testbed for probing physical and chemical processes at the molecular scale. Due to nanometric confinement, charge and energy transport in MSJs are governed by quantum mechanically dictated energy profiles, which can be tuned chemically or physically with atomic precision, offering rich possibilities beyond conventional semiconductor devices. While charge transport in MSJs has been extensively studied over the past two decades, understanding energy conversion and transport in MSJs has only become experimentally attainable in recent years. As demonstrated recently, by tuning the quantum interplay between the electrodes, the molecular core, and the contact interfaces, energy processes can be manipulated to achieve desired functionalities, opening new avenues for molecular electronics, energy harvesting, and sensing applications. This Review provides a comprehensive overview and critical analysis of various forms of energy conversion and transport processes in MSJs and their associated applications. We elaborate on energy-related processes mediated by the interaction between the core molecular structure in MSJs and different external stimuli, such as light, heat, electric field, magnetic field, force, and other environmental cues. Key topics covered include photovoltaics, electroluminescence, thermoelectricity, heat conduction, catalysis, spin-mediated phenomena, and vibrational effects. The review concludes with a discussion of existing challenges and future opportunities, aiming to facilitate in-depth future investigation of promising experimental platforms, molecular design principles, control strategies, and new application scenarios.","PeriodicalId":8200,"journal":{"name":"Applied physics reviews","volume":"15 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142536715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Third-generation photovoltaic materials, including metal halide perovskites (MHPs), colloidal quantum dots (QDs), copper zinc tin sulfide (CZTS), and organic semiconductors, among others, have become attractive in the past two decades. Unlike their first- and second-generation counterparts, these advanced materials boast properties beyond mere photovoltaic performance, such as mechanical flexibility, light weight, and cost-effectiveness. Meanwhile, these materials possess more intricate crystalline structures that aid in understanding and predicting their transport properties. In particular, the distinctive phonon dispersions in MHPs, the layered architecture in quasi-two-dimensional (2D) perovskites, the strong quantum confinement in QDs, and the complex crystal structures interspersed with abundant disorders in quaternary CZTS result in unique and sometimes anomalous thermal transport behaviors. Concurrently, the criticality of thermal management in applications such as photovoltaics, thermoelectrics, light emitting diodes, and photodetection devices has received increased recognition, considering that many of these third-generation photovoltaic materials are not good thermal conductors. Effective thermal management necessitates precise measurement, advanced modeling, and a profound understanding and interpretation of thermal transport properties in these novel materials. In this review, we provide a comprehensive summary of various techniques for measuring thermal transport properties of these materials and discuss the ultralow thermal conductivities of three-dimensional (3D) MHPs, superlattice-like thermal transport in 2D perovskites, and novel thermal transport characteristics inherent in QDs and CZTS. By collecting and comparing the literature-reported results, we offer a thorough discussion on the thermal transport phenomenon in these materials. The collective understanding from the literature in this area, as reviewed in this article, can provide guidance for improving thermal management across a wide spectrum of applications extending beyond photovoltaics.
{"title":"Thermal transport in metal halide perovskites and other third-generation photovoltaic materials","authors":"Du Chen, Shunran Li, Bowen Li, Peijun Guo","doi":"10.1063/5.0226632","DOIUrl":"https://doi.org/10.1063/5.0226632","url":null,"abstract":"Third-generation photovoltaic materials, including metal halide perovskites (MHPs), colloidal quantum dots (QDs), copper zinc tin sulfide (CZTS), and organic semiconductors, among others, have become attractive in the past two decades. Unlike their first- and second-generation counterparts, these advanced materials boast properties beyond mere photovoltaic performance, such as mechanical flexibility, light weight, and cost-effectiveness. Meanwhile, these materials possess more intricate crystalline structures that aid in understanding and predicting their transport properties. In particular, the distinctive phonon dispersions in MHPs, the layered architecture in quasi-two-dimensional (2D) perovskites, the strong quantum confinement in QDs, and the complex crystal structures interspersed with abundant disorders in quaternary CZTS result in unique and sometimes anomalous thermal transport behaviors. Concurrently, the criticality of thermal management in applications such as photovoltaics, thermoelectrics, light emitting diodes, and photodetection devices has received increased recognition, considering that many of these third-generation photovoltaic materials are not good thermal conductors. Effective thermal management necessitates precise measurement, advanced modeling, and a profound understanding and interpretation of thermal transport properties in these novel materials. In this review, we provide a comprehensive summary of various techniques for measuring thermal transport properties of these materials and discuss the ultralow thermal conductivities of three-dimensional (3D) MHPs, superlattice-like thermal transport in 2D perovskites, and novel thermal transport characteristics inherent in QDs and CZTS. By collecting and comparing the literature-reported results, we offer a thorough discussion on the thermal transport phenomenon in these materials. The collective understanding from the literature in this area, as reviewed in this article, can provide guidance for improving thermal management across a wide spectrum of applications extending beyond photovoltaics.","PeriodicalId":8200,"journal":{"name":"Applied physics reviews","volume":"60 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142490608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Tao Feng, Xinglin Luo, Zhuohao Liu, Xingwang Liu, Xiaohui Yan, Gang Li, Wenlei Zhang, Kaiying Wang
Flexible electrode is crucial for wearable electronic devices. To prevent performance degradation due to bending or stretching, the development of highly flexible and durable materials is imperative. Here, we address this challenge by selecting stainless-steel electrodes with excellent stability and flexibility. Through an anodization process on the stainless steel, we created an integrated flexible iron oxide electrode. Chemical vapor deposition and ion implantation were employed to develop concentration-controllable N-doped iron oxide electrodes. Comparative analysis highlights the outstanding performance of ion-implanted electrodes, with a specific capacitance increase of up to 3.01 times (332.375 mF cm−2) at 1 mA cm−2. The N-doped electrode exhibits a capacitance retention of 76.67% after 8000 cycles. Density functional theory calculations reveal N-induced lattice distortion, enhancing ion transport and reducing the bandgap. Leveraging these insights, a flexible asymmetric supercapacitor is assembled, demonstrating exceptional stability and capacitance characteristics across different voltages. The flexibility of the stainless-steel substrate enables the FSC to maintain capacitive performance during bending. This research presents a promising solution for high-performance and stable capacitors in electrochemical energy storage applications.
柔性电极对于可穿戴电子设备至关重要。为了防止因弯曲或拉伸而导致性能下降，开发高柔性和耐用的材料势在必行。在此，我们选择了具有出色稳定性和柔韧性的不锈钢电极来应对这一挑战。通过对不锈钢进行阳极氧化处理，我们创造出了一种集成的柔性氧化铁电极。我们采用化学气相沉积和离子注入技术开发出浓度可控的掺 N 氧化铁电极。对比分析凸显了离子注入电极的卓越性能，在 1 mA cm-2 的条件下，比电容增加了 3.01 倍（332.375 mF cm-2）。掺杂 N 的电极在 8000 次循环后的电容保持率为 76.67%。密度泛函理论计算揭示了 N 诱导的晶格畸变，从而增强了离子传输并减小了带隙。利用这些见解，我们组装出了一种灵活的非对称超级电容器，在不同电压下均表现出卓越的稳定性和电容特性。不锈钢基板的柔韧性使 FSC 能够在弯曲过程中保持电容性能。这项研究为电化学储能应用中的高性能稳定电容器提供了一种前景广阔的解决方案。
{"title":"Nanoarchitectonics of highly flexible iron-oxide nanoporous electrodes on stainless steel substrate for wearable supercapacitors","authors":"Tao Feng, Xinglin Luo, Zhuohao Liu, Xingwang Liu, Xiaohui Yan, Gang Li, Wenlei Zhang, Kaiying Wang","doi":"10.1063/5.0225825","DOIUrl":"https://doi.org/10.1063/5.0225825","url":null,"abstract":"Flexible electrode is crucial for wearable electronic devices. To prevent performance degradation due to bending or stretching, the development of highly flexible and durable materials is imperative. Here, we address this challenge by selecting stainless-steel electrodes with excellent stability and flexibility. Through an anodization process on the stainless steel, we created an integrated flexible iron oxide electrode. Chemical vapor deposition and ion implantation were employed to develop concentration-controllable N-doped iron oxide electrodes. Comparative analysis highlights the outstanding performance of ion-implanted electrodes, with a specific capacitance increase of up to 3.01 times (332.375 mF cm−2) at 1 mA cm−2. The N-doped electrode exhibits a capacitance retention of 76.67% after 8000 cycles. Density functional theory calculations reveal N-induced lattice distortion, enhancing ion transport and reducing the bandgap. Leveraging these insights, a flexible asymmetric supercapacitor is assembled, demonstrating exceptional stability and capacitance characteristics across different voltages. The flexibility of the stainless-steel substrate enables the FSC to maintain capacitive performance during bending. This research presents a promising solution for high-performance and stable capacitors in electrochemical energy storage applications.","PeriodicalId":8200,"journal":{"name":"Applied physics reviews","volume":"14 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142489710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Akbar I. Inamdar, Amol S. Salunke, Nabeen K. Shrestha, Hyunsik Im
Maintaining an acceptable quality of life worldwide increasingly depends on the availability of clean and cost-effective energy, with power consumption expected to double by 2050. Therefore, the need for sustainable and affordable green energy has spurred innovative electrocatalysis research with the goal to develop materials and processes that are capable of producing environmentally friendly, carbon-neutral, clean, and green hydrogen fuel as an alternative to fossil fuel. In particular, heterostructured catalysts consisting of transition metal oxides and sulfides have emerged as a capable component of green energy technology. The dual functionality of these catalysts allows for water splitting, while the selectivity of the catalytic materials creates synergetic effects based on their electronic structure, surface composition, and electrochemical surface area. In this review, we examine the latest research and developments, synthesis methods, design strategies, reaction mechanisms, and performance outcomes for oxide/sulfide heterostructures. The review begins by introducing the current demand for hydrogen energy and electrocatalytic water-splitting and then describes the fundamental design principles for oxide/sulfide heterostructures and their hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance. A large part of the review is then dedicated to a comprehensive discussion of the various transition metal oxide/sulfide heterostructures designed for the OER, the HER, and two-electrode electrolyzer applications. In addition, the use of in situ and operando techniques, which provide crucial information for the design of effective electrocatalysts, is described. We also discuss the present status of electrocatalysis technology, including the challenges it faces and its future prospects as a means to achieve carbon-neutral hydrogen production. Overall, this review delivers a summary of the latest developments in electrocatalysis based on oxide/sulfide heterostructures for use in green hydrogen production.
{"title":"Heterogeneous oxide/sulfide materials as superior bifunctional electrocatalysts for carbon-neutral green hydrogen production: A short review","authors":"Akbar I. Inamdar, Amol S. Salunke, Nabeen K. Shrestha, Hyunsik Im","doi":"10.1063/5.0221098","DOIUrl":"https://doi.org/10.1063/5.0221098","url":null,"abstract":"Maintaining an acceptable quality of life worldwide increasingly depends on the availability of clean and cost-effective energy, with power consumption expected to double by 2050. Therefore, the need for sustainable and affordable green energy has spurred innovative electrocatalysis research with the goal to develop materials and processes that are capable of producing environmentally friendly, carbon-neutral, clean, and green hydrogen fuel as an alternative to fossil fuel. In particular, heterostructured catalysts consisting of transition metal oxides and sulfides have emerged as a capable component of green energy technology. The dual functionality of these catalysts allows for water splitting, while the selectivity of the catalytic materials creates synergetic effects based on their electronic structure, surface composition, and electrochemical surface area. In this review, we examine the latest research and developments, synthesis methods, design strategies, reaction mechanisms, and performance outcomes for oxide/sulfide heterostructures. The review begins by introducing the current demand for hydrogen energy and electrocatalytic water-splitting and then describes the fundamental design principles for oxide/sulfide heterostructures and their hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance. A large part of the review is then dedicated to a comprehensive discussion of the various transition metal oxide/sulfide heterostructures designed for the OER, the HER, and two-electrode electrolyzer applications. In addition, the use of in situ and operando techniques, which provide crucial information for the design of effective electrocatalysts, is described. We also discuss the present status of electrocatalysis technology, including the challenges it faces and its future prospects as a means to achieve carbon-neutral hydrogen production. Overall, this review delivers a summary of the latest developments in electrocatalysis based on oxide/sulfide heterostructures for use in green hydrogen production.","PeriodicalId":8200,"journal":{"name":"Applied physics reviews","volume":"31 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142489529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Yu Ding, Xiangming Xu, Zhe Zhuang, Yimeng Sang, Mei Cui, Wenxin Li, Yu Yan, Tao Tao, Weizong Xu, Fangfang Ren, Jiandong Ye, Dunjun Chen, Hai Lu, Rong Zhang, Husam N. Alshareef, Bin Liu
High-responsivity and energy-saving ultraviolet photodetectors become crucial components for modern optoelectronic information sensing and communication systems. This study presents an advanced self-powered MXene/GaN Schottky ultraviolet photodetector that features a high-quality van der Waals interface to enhance photoresponsivity. The photodetector exhibits a high responsivity of 681.6 mA W−1 and a significant detectivity of 7.65 × 1013 Jones at zero bias. In a self-powered mode, the detector can operate robustly even under dim illumination (0.15 μW cm−2) due to the excellent Schottky contact and low amount of defect states at the MXene/GaN interface, which presents a strong intrinsic electric field. The photodetector has a high ultraviolet/visible rejection ratio (R360 nm/R400 nm) of 3.9 × 103 and a signal to noise ratio (SNR) of 2.4 × 105, which enable discrimination against visible light interference in real-world scenarios. We also demonstrated that the photodetectors worked well as ultraviolet signal receivers in an optical information communication system to accurately recognize pulsed signals transmitted from an ultraviolet light-emitting diode. These findings imply the great potential of van der Waals Schottky junctions between 2D MXenes and III-nitrides for high-performance photodetection and sensing in many integrated optoelectronic platforms.
{"title":"Self-powered MXene/GaN van der Waals Schottky ultraviolet photodetectors with exceptional responsivity and stability","authors":"Yu Ding, Xiangming Xu, Zhe Zhuang, Yimeng Sang, Mei Cui, Wenxin Li, Yu Yan, Tao Tao, Weizong Xu, Fangfang Ren, Jiandong Ye, Dunjun Chen, Hai Lu, Rong Zhang, Husam N. Alshareef, Bin Liu","doi":"10.1063/5.0209698","DOIUrl":"https://doi.org/10.1063/5.0209698","url":null,"abstract":"High-responsivity and energy-saving ultraviolet photodetectors become crucial components for modern optoelectronic information sensing and communication systems. This study presents an advanced self-powered MXene/GaN Schottky ultraviolet photodetector that features a high-quality van der Waals interface to enhance photoresponsivity. The photodetector exhibits a high responsivity of 681.6 mA W−1 and a significant detectivity of 7.65 × 1013 Jones at zero bias. In a self-powered mode, the detector can operate robustly even under dim illumination (0.15 μW cm−2) due to the excellent Schottky contact and low amount of defect states at the MXene/GaN interface, which presents a strong intrinsic electric field. The photodetector has a high ultraviolet/visible rejection ratio (R360 nm/R400 nm) of 3.9 × 103 and a signal to noise ratio (SNR) of 2.4 × 105, which enable discrimination against visible light interference in real-world scenarios. We also demonstrated that the photodetectors worked well as ultraviolet signal receivers in an optical information communication system to accurately recognize pulsed signals transmitted from an ultraviolet light-emitting diode. These findings imply the great potential of van der Waals Schottky junctions between 2D MXenes and III-nitrides for high-performance photodetection and sensing in many integrated optoelectronic platforms.","PeriodicalId":8200,"journal":{"name":"Applied physics reviews","volume":"3 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142489528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Sheng Jiang, Linrong Yao, Shun Wang, Di Wang, Long Liu, Akash Kumar, Ahmad A. Awad, Artem Litvinenko, Martina Ahlberg, Roman Khymyn, Sunjae Chung, Guozhong Xing, Johan Åkerman
Spin-torque nano-oscillators (STNOs) have emerged as an intriguing category of spintronic devices based on spin transfer torque to excite magnetic moment dynamics. The ultra-wide frequency tuning range, nanoscale size, and rich nonlinear dynamics have positioned STNOs at the forefront of advanced technologies, holding substantial promise in wireless communication, and neuromorphic computing. This review surveys recent advances in STNOs, including architectures, experimental methodologies, magnetodynamics, and device properties. Significantly, we focus on the exciting applications of STNOs, in fields ranging from signal processing to energy-efficient computing. Finally, we summarize the recent advancements and prospects for STNOs. This review aims to serve as a valuable resource for readers from diverse backgrounds, offering a concise yet comprehensive introduction to STNOs. It is designed to benefit newcomers seeking an entry point into the field and established members of the STNOs community, providing them with insightful perspectives on future developments.
{"title":"Spin-torque nano-oscillators and their applications","authors":"Sheng Jiang, Linrong Yao, Shun Wang, Di Wang, Long Liu, Akash Kumar, Ahmad A. Awad, Artem Litvinenko, Martina Ahlberg, Roman Khymyn, Sunjae Chung, Guozhong Xing, Johan Åkerman","doi":"10.1063/5.0221877","DOIUrl":"https://doi.org/10.1063/5.0221877","url":null,"abstract":"Spin-torque nano-oscillators (STNOs) have emerged as an intriguing category of spintronic devices based on spin transfer torque to excite magnetic moment dynamics. The ultra-wide frequency tuning range, nanoscale size, and rich nonlinear dynamics have positioned STNOs at the forefront of advanced technologies, holding substantial promise in wireless communication, and neuromorphic computing. This review surveys recent advances in STNOs, including architectures, experimental methodologies, magnetodynamics, and device properties. Significantly, we focus on the exciting applications of STNOs, in fields ranging from signal processing to energy-efficient computing. Finally, we summarize the recent advancements and prospects for STNOs. This review aims to serve as a valuable resource for readers from diverse backgrounds, offering a concise yet comprehensive introduction to STNOs. It is designed to benefit newcomers seeking an entry point into the field and established members of the STNOs community, providing them with insightful perspectives on future developments.","PeriodicalId":8200,"journal":{"name":"Applied physics reviews","volume":"9 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142488398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
A novel tapered quartz tuning fork (QTF) was designed to enhance its stress magnitude and charge distribution in QTF-based laser spectroscopy, which had a low resonant frequency of 7.83 kHz and a wide fork gap for long energy accumulation time and easy optical alignment. Compared to the reported rectangular QTF, this tapered QTF transfers the maximum stress position from the root to the middle to improve its sensing performance. Furthermore, the unique design eliminates the 90° right angles typically found in standard QTFs, which often lead to undesired “webs” and “facets” during the etching process. This design minimizes performance degradation by reducing the presence of residual unexpected materials. QTF-based laser spectroscopy of quartz-enhanced photoacoustic spectroscopy (QEPAS) and light-induced thermoelastic spectroscopy (LITES) were adopted to verify its performance. Compared with the widely used standard QTF, the total surface charge of the tapered QTF was improved 5.08 times and 5.69 times in QEPAS and LITES simulations, respectively. Experiments revealed that this tapered QTF-based QEPAS sensor had a 3.02 times improvement in signal-to-noise-ratio (SNR) compared to the standard QTF-based system. Adding an acoustic micro-resonator to this tapered QTF-based QEPAS sensor improved the signal level by 97.20 times. The minimum detection limit (MDL) for acetylene (C2H2) detection was determined to be 16.45 ppbv. In the LITES technique, compared to the standard QTF, this tapered QTF-based sensor had a 3.60 times improvement in SNR. The MDL for C2H2 detection was determined to be 146.39 ppbv.
{"title":"A novel tapered quartz tuning fork-based laser spectroscopy sensing","authors":"Yufei Ma, Shunda Qiao, Runqiu Wang, Ying He, Chao Fang, Tiantian Liang","doi":"10.1063/5.0214874","DOIUrl":"https://doi.org/10.1063/5.0214874","url":null,"abstract":"A novel tapered quartz tuning fork (QTF) was designed to enhance its stress magnitude and charge distribution in QTF-based laser spectroscopy, which had a low resonant frequency of 7.83 kHz and a wide fork gap for long energy accumulation time and easy optical alignment. Compared to the reported rectangular QTF, this tapered QTF transfers the maximum stress position from the root to the middle to improve its sensing performance. Furthermore, the unique design eliminates the 90° right angles typically found in standard QTFs, which often lead to undesired “webs” and “facets” during the etching process. This design minimizes performance degradation by reducing the presence of residual unexpected materials. QTF-based laser spectroscopy of quartz-enhanced photoacoustic spectroscopy (QEPAS) and light-induced thermoelastic spectroscopy (LITES) were adopted to verify its performance. Compared with the widely used standard QTF, the total surface charge of the tapered QTF was improved 5.08 times and 5.69 times in QEPAS and LITES simulations, respectively. Experiments revealed that this tapered QTF-based QEPAS sensor had a 3.02 times improvement in signal-to-noise-ratio (SNR) compared to the standard QTF-based system. Adding an acoustic micro-resonator to this tapered QTF-based QEPAS sensor improved the signal level by 97.20 times. The minimum detection limit (MDL) for acetylene (C2H2) detection was determined to be 16.45 ppbv. In the LITES technique, compared to the standard QTF, this tapered QTF-based sensor had a 3.60 times improvement in SNR. The MDL for C2H2 detection was determined to be 146.39 ppbv.","PeriodicalId":8200,"journal":{"name":"Applied physics reviews","volume":"40 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142488418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
S. Mayr, J. Förster, S. Finizio, K. Schultheiss, R. A. Gallardo, R. Narkovicz, G. Dieterle, A. Semisalova, J. Bailey, E. Kirk, A. Suszka, J. Lindner, J. Gräfe, J. Raabe, G. Schütz, M. Weigand, H. Stoll, S. Wintz
Time-resolved x-ray microscopy is used in a low-alpha synchrotron operation mode to image spin dynamics at an unprecedented combination of temporal and spatial resolution. Thereby, nanoscale spin waves with wavelengths down to 70 nm and frequencies up to 30 GHz are directly observed in ferromagnetic thin film microelements with spin vortex ground states. In an antiparallel ferromagnetic bilayer system, we detect the propagation of both optic and acoustic modes, the latter exhibiting even a strong non-reciprocity. In single-layer systems, quasi-uniform spin waves are observed together with modes of higher order (up to the 4th order), bearing precessional nodes over the thickness of the film. Furthermore, the effects of magnetic material properties, film thickness, and magnetic fields on the spin-wave spectrum are determined experimentally. Our experimental results are consistent with numerical calculations from a micromagnetic theory even on these so-far unexplored time- and length scales.
时间分辨 X 射线显微镜在低阿尔法同步加速器运行模式下，以前所未有的时间和空间分辨率组合对自旋动力学进行成像。因此，在具有自旋漩涡基态的铁磁薄膜微元素中，可以直接观测到波长低至 70 纳米、频率高达 30 千兆赫的纳米级自旋波。在反平行铁磁双层系统中，我们探测到了光学和声学模式的传播，后者甚至表现出很强的非互易性。在单层系统中，我们观测到了准均匀自旋波和高阶（最高达 4 阶）模式，它们在薄膜厚度上具有前序节点。此外，我们还通过实验确定了磁性材料特性、薄膜厚度和磁场对自旋波谱的影响。我们的实验结果与微磁理论的数值计算结果一致，甚至在这些迄今为止尚未探索的时间和长度尺度上也是如此。
{"title":"Time-resolved x-ray imaging of nanoscale spin-wave dynamics at multi-GHz frequencies using low-alpha synchrotron operation","authors":"S. Mayr, J. Förster, S. Finizio, K. Schultheiss, R. A. Gallardo, R. Narkovicz, G. Dieterle, A. Semisalova, J. Bailey, E. Kirk, A. Suszka, J. Lindner, J. Gräfe, J. Raabe, G. Schütz, M. Weigand, H. Stoll, S. Wintz","doi":"10.1063/5.0206576","DOIUrl":"https://doi.org/10.1063/5.0206576","url":null,"abstract":"Time-resolved x-ray microscopy is used in a low-alpha synchrotron operation mode to image spin dynamics at an unprecedented combination of temporal and spatial resolution. Thereby, nanoscale spin waves with wavelengths down to 70 nm and frequencies up to 30 GHz are directly observed in ferromagnetic thin film microelements with spin vortex ground states. In an antiparallel ferromagnetic bilayer system, we detect the propagation of both optic and acoustic modes, the latter exhibiting even a strong non-reciprocity. In single-layer systems, quasi-uniform spin waves are observed together with modes of higher order (up to the 4th order), bearing precessional nodes over the thickness of the film. Furthermore, the effects of magnetic material properties, film thickness, and magnetic fields on the spin-wave spectrum are determined experimentally. Our experimental results are consistent with numerical calculations from a micromagnetic theory even on these so-far unexplored time- and length scales.","PeriodicalId":8200,"journal":{"name":"Applied physics reviews","volume":"234 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142487358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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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