Samriti, Sahil Thakur, Abhijeet Ojha, Rajeev Gupta, M. Bechelany, A. Kuznetsov, H. Swart, Jai Prakash
Graphene oxide (GO) has become one of the emerging and important sole photocatalyst nanomaterials in recent years due to its exceptional/tunable optoelectronic properties, multifunctionality, and eco‐friendly nature. However, challenges remain in tuning surface chemistry, tailoring the band gap, developing doping strategies, and understanding the sole photocatalytic mechanism. This contribution investigated the synthesis of GO via the improved Hummers method by varying the ratio of the oxidizing agents (K2Cr2O7:KMnO4), as well as modifications by nitrogen (N) and boron (B) doping in view of its applications in photocatalytic degradation of organic dye pollutants. Furthermore, changes in surface chemistry, optical, compositional, morphological, and structural properties are investigated to understand the photocatalytic mechanism. The synthesized GO showed a broad spectrum of light absorption with a tunable band gap of 2.4–4.3 eV and exhibited more than 91% degradation of methylene blue dye under direct sunlight. However, the photocatalytic activity decreased after N and B doping attributed to reduced oxygen‐containing functional groups, low surface area, and dopants‐induced bonding configurations within the GO structure. This study provides a new insight into replacing metallic semiconductor photocatalysts with highly affordable, environmentally friendly, and potent metal‐free GO photocatalysts.
近年来，氧化石墨烯（GO）因其卓越/可调的光电特性、多功能性和生态友好性，已成为新兴的重要唯一光催化纳米材料之一。然而，在调整表面化学性质、定制带隙、开发掺杂策略以及了解唯一光催化机理方面仍存在挑战。本文研究了通过改变氧化剂（K2Cr2O7:KMnO4）的比例，以及氮（N）和硼（B）的掺杂改性，采用改进的 Hummers 法合成 GO，以期将其应用于有机染料污染物的光催化降解。此外，还研究了表面化学、光学、成分、形态和结构特性的变化，以了解光催化机理。合成的 GO 具有较宽的光吸收光谱，其带隙为 2.4-4.3 eV，在阳光直射下对亚甲蓝染料的降解率超过 91%。然而，在掺杂了 N 和 B 后，光催化活性降低了，这归因于含氧官能团的减少、低表面积以及掺杂剂在 GO 结构中引起的键合构型。这项研究为用经济实惠、环保和高效的无金属 GO 光催化剂取代金属半导体光催化剂提供了新的视角。
{"title":"Graphene Oxide as Novel Visible Light Active Photocatalyst: Synthesis, Modification by Nitrogen and Boron Doping, and Photocatalytic Application","authors":"Samriti, Sahil Thakur, Abhijeet Ojha, Rajeev Gupta, M. Bechelany, A. Kuznetsov, H. Swart, Jai Prakash","doi":"10.1002/pssa.202400169","DOIUrl":"https://doi.org/10.1002/pssa.202400169","url":null,"abstract":"Graphene oxide (GO) has become one of the emerging and important sole photocatalyst nanomaterials in recent years due to its exceptional/tunable optoelectronic properties, multifunctionality, and eco‐friendly nature. However, challenges remain in tuning surface chemistry, tailoring the band gap, developing doping strategies, and understanding the sole photocatalytic mechanism. This contribution investigated the synthesis of GO via the improved Hummers method by varying the ratio of the oxidizing agents (K2Cr2O7:KMnO4), as well as modifications by nitrogen (N) and boron (B) doping in view of its applications in photocatalytic degradation of organic dye pollutants. Furthermore, changes in surface chemistry, optical, compositional, morphological, and structural properties are investigated to understand the photocatalytic mechanism. The synthesized GO showed a broad spectrum of light absorption with a tunable band gap of 2.4–4.3 eV and exhibited more than 91% degradation of methylene blue dye under direct sunlight. However, the photocatalytic activity decreased after N and B doping attributed to reduced oxygen‐containing functional groups, low surface area, and dopants‐induced bonding configurations within the GO structure. This study provides a new insight into replacing metallic semiconductor photocatalysts with highly affordable, environmentally friendly, and potent metal‐free GO photocatalysts.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":"67 22","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141358155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ye Liang, Xiuyuan He, Xi Feng, Yuanlei Zhang, Jie Zhang, Wen Liu
This study investigates the impact of gate field plate (G‐FP) lengths on the dynamic on‐resistance degradation in partially recessed‐gate D‐mode GaN metal–insulator–semiconductor high‐electron‐mobility transistors (MIS‐HEMTs). Devices with G‐FPs of varying lengths are fabricated, and their electrical characteristics are evaluated. It is found that G‐FPs effectively reduce electron trapping and suppress the dynamic on‐resistance degradation, leading to improved device performance. The study provides design suggestions for enhancing the reliability and stability of AlGaN/GaN‐based MIS‐HEMTs.
本研究探讨了栅极场板（G-FP）长度对部分凹栅极 D 模式氮化镓金属绝缘体半导体高电子迁移率晶体管（MIS-HEMT）动态导通电阻衰减的影响。我们制作了具有不同长度 G-FPs 的器件，并对其电气特性进行了评估。研究发现，G-FPs 能有效减少电子捕获并抑制动态导通电阻衰减，从而提高器件性能。这项研究为提高基于 AlGaN/GaN 的 MIS-HEMT 的可靠性和稳定性提供了设计建议。
{"title":"Dynamic RON Degradation Suppression by Gate Field Plate in Partially Recessed AlGaN/GaN Metal–Insulator–Semiconductor High‐Electron‐Mobility Transistors","authors":"Ye Liang, Xiuyuan He, Xi Feng, Yuanlei Zhang, Jie Zhang, Wen Liu","doi":"10.1002/pssa.202300976","DOIUrl":"https://doi.org/10.1002/pssa.202300976","url":null,"abstract":"This study investigates the impact of gate field plate (G‐FP) lengths on the dynamic on‐resistance degradation in partially recessed‐gate D‐mode GaN metal–insulator–semiconductor high‐electron‐mobility transistors (MIS‐HEMTs). Devices with G‐FPs of varying lengths are fabricated, and their electrical characteristics are evaluated. It is found that G‐FPs effectively reduce electron trapping and suppress the dynamic on‐resistance degradation, leading to improved device performance. The study provides design suggestions for enhancing the reliability and stability of AlGaN/GaN‐based MIS‐HEMTs.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":"70 21","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141358087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jaehyeok Park, Seokjun Shin, Dong‐Guang Zheng, Kyu Sang Kim, Dong‐Pyo Han
This study attempts to understand and elucidate the factors limiting/determining the external quantum efficiency (EQE) of light‐emitting diodes (LEDs) depending on material systems, i.e., III‐arsenide (GaAs), III‐phosphide (AlGaInP), and III‐nitride (GaInN), via the temperature measurements (30–500 K). The behaviors of EQEs are investigated carefully in terms of the thermal droop and efficiency droop, revealing that the thermal droop in the AlGaInP and GaAs LEDs, while the efficiency droop in the GaInN LEDs, is a critical factor limiting the EQE. To deepen the insight, the EQE is separated into internal quantum efficiency (IQE) and light‐extraction efficiency (LEE). Further, the IQE is separated into radiative efficiency (RE) and injection efficiency (IE). The analysis shows that the LEE plays a significant role in the thermal droop for the AlGaInP and GaAs LEDs. Meanwhile, the IE and RE play a significant role in the EQE reduction of the blue and red LEDs at high temperatures and high current injection.
本研究试图通过温度测量（30-500 K）来了解和阐明限制/决定发光二极管（LED）外部量子效率（EQE）的因素，这些因素取决于材料系统，即三砷化镓（GaAs）、三磷化镓（AlGaInP）和三氮化镓（GaInN）。从热下降和效率下降的角度仔细研究了 EQE 的行为，发现 AlGaInP 和砷化镓 LED 的热下降以及 GaInN LED 的效率下降是限制 EQE 的关键因素。为了加深理解，EQE 被分为内部量子效率 (IQE) 和光提取效率 (LEE)。此外，IQE 还分为辐射效率 (RE) 和注入效率 (IE)。分析表明，LEE 对 AlGaInP 和 GaAs LED 的热衰减起着重要作用。同时，在高温和高电流注入条件下，IE 和 RE 对蓝光和红光 LED 的 EQE 降低起着重要作用。
{"title":"Comparative Study on Temperature‐Dependent Internal Quantum Efficiency and Light–Extraction Efficiency in III‐Nitride–, III‐Phosphide–, and III‐Arsenide–based Light‐Emitting Diodes","authors":"Jaehyeok Park, Seokjun Shin, Dong‐Guang Zheng, Kyu Sang Kim, Dong‐Pyo Han","doi":"10.1002/pssa.202400063","DOIUrl":"https://doi.org/10.1002/pssa.202400063","url":null,"abstract":"This study attempts to understand and elucidate the factors limiting/determining the external quantum efficiency (EQE) of light‐emitting diodes (LEDs) depending on material systems, i.e., III‐arsenide (GaAs), III‐phosphide (AlGaInP), and III‐nitride (GaInN), via the temperature measurements (30–500 K). The behaviors of EQEs are investigated carefully in terms of the thermal droop and efficiency droop, revealing that the thermal droop in the AlGaInP and GaAs LEDs, while the efficiency droop in the GaInN LEDs, is a critical factor limiting the EQE. To deepen the insight, the EQE is separated into internal quantum efficiency (IQE) and light‐extraction efficiency (LEE). Further, the IQE is separated into radiative efficiency (RE) and injection efficiency (IE). The analysis shows that the LEE plays a significant role in the thermal droop for the AlGaInP and GaAs LEDs. Meanwhile, the IE and RE play a significant role in the EQE reduction of the blue and red LEDs at high temperatures and high current injection.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":"34 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141360059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Minerva Gonzalez, S. Margueron, Tomas Murauskas, Pascal Boulet, Ludovic Gauthier‐Manuel, Bernard Dulmet, A. Bartasyte
The effect of key parameters such as time, temperature, and equilibration powder concentration in vapor transport equilibration (VTE) treatment on the Li2O content of initially congruent X‐, Y‐, and Z‐cut LiTaO3 crystals is experimentally investigated. The Li2O content across the thickness of the crystal is estimated by Raman spectroscopy with accuracy of 0.05–0.15 mol%. The Li2O loss from equilibration powders has been monitored as a function of treatment temperature and duration. The results show that the Li2O content in the crystal nonlinearly depends on the equilibration powder composition and that homogeneous stoichiometric LiTaO3 crystals can be obtained by treatment for at least 36h at 1250°C in Li2O‐rich atmosphere, created by powders containing >54 mol% of Li2O. The anisotropic Li+ diffusion coefficients and its activation energy are also experimentally estimated. Finally, the VTE conditions are defined for the production of different cuts of LiTaO3 crystals with controlled homogeneous Li2O nonstoichiometry in the range from subcongruent to stoichiometric compositions.
{"title":"Influence of Parameters in Vapor Transport Equilibration Treatment on Composition and Homogeneity of LiTaO3 Single Crystals","authors":"Minerva Gonzalez, S. Margueron, Tomas Murauskas, Pascal Boulet, Ludovic Gauthier‐Manuel, Bernard Dulmet, A. Bartasyte","doi":"10.1002/pssa.202400129","DOIUrl":"https://doi.org/10.1002/pssa.202400129","url":null,"abstract":"The effect of key parameters such as time, temperature, and equilibration powder concentration in vapor transport equilibration (VTE) treatment on the Li2O content of initially congruent X‐, Y‐, and Z‐cut LiTaO3 crystals is experimentally investigated. The Li2O content across the thickness of the crystal is estimated by Raman spectroscopy with accuracy of 0.05–0.15 mol%. The Li2O loss from equilibration powders has been monitored as a function of treatment temperature and duration. The results show that the Li2O content in the crystal nonlinearly depends on the equilibration powder composition and that homogeneous stoichiometric LiTaO3 crystals can be obtained by treatment for at least 36h at 1250°C in Li2O‐rich atmosphere, created by powders containing >54 mol% of Li2O. The anisotropic Li+ diffusion coefficients and its activation energy are also experimentally estimated. Finally, the VTE conditions are defined for the production of different cuts of LiTaO3 crystals with controlled homogeneous Li2O nonstoichiometry in the range from subcongruent to stoichiometric compositions.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":"67 19","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141358157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Based on the ultrafast and extremely strong interaction between laser pulses and materials, ultrafast laser irradiation can break the solid solubility constraints and enable hyperdoping of impurities. This process overcomes the bandgap constraints of crystalline silicon, resulting in heightened absorption across a broad spectral range spanning from ultraviolet to infrared wavelengths, therefore commonly referred to as black silicon (b‐Si). The b‐Si demonstrates significant changes in optoelectronic properties, making it highly promising for applications in silicon photonics. Specifically, b‐Si photodetectors exhibit distinct advantages in terms of high photoelectric gain at low voltage, ultrabroadband spectral responsivity, large dynamic range, and suitability for operation over a wide temperature range. These properties address the limitations of traditional silicon photodetectors, showcasing great potential for applications in optoelectronic integration, artificial intelligence, information technology, energy devices, and beyond. This review focuses on b‐Si achieved through ultrafast laser processing, with a special emphasis on its applications in photodetectors. The mechanism of ultrafast laser irradiation and the properties of hyperdoped silicon are discussed. Then, the research progresses and state‐of‐the‐art b‐Si photodetectors are introduced, as well as working mechanism and potential application expansion. Finally, the development prospects of b‐Si photodetectors based on ultrafast laser hyperdoping are predicted.
{"title":"Ultrafast Laser Hyperdoped Black Silicon and Its Application in Photodetectors: A Review","authors":"Song Huang, Xiaorong Jin, Qiang Wu, Guanting Song, Jiaxin Cao, Xu Zhou, Haonan Jiang, Weiqing Gao, Jingjun Xu","doi":"10.1002/pssa.202400127","DOIUrl":"https://doi.org/10.1002/pssa.202400127","url":null,"abstract":"Based on the ultrafast and extremely strong interaction between laser pulses and materials, ultrafast laser irradiation can break the solid solubility constraints and enable hyperdoping of impurities. This process overcomes the bandgap constraints of crystalline silicon, resulting in heightened absorption across a broad spectral range spanning from ultraviolet to infrared wavelengths, therefore commonly referred to as black silicon (b‐Si). The b‐Si demonstrates significant changes in optoelectronic properties, making it highly promising for applications in silicon photonics. Specifically, b‐Si photodetectors exhibit distinct advantages in terms of high photoelectric gain at low voltage, ultrabroadband spectral responsivity, large dynamic range, and suitability for operation over a wide temperature range. These properties address the limitations of traditional silicon photodetectors, showcasing great potential for applications in optoelectronic integration, artificial intelligence, information technology, energy devices, and beyond. This review focuses on b‐Si achieved through ultrafast laser processing, with a special emphasis on its applications in photodetectors. The mechanism of ultrafast laser irradiation and the properties of hyperdoped silicon are discussed. Then, the research progresses and state‐of‐the‐art b‐Si photodetectors are introduced, as well as working mechanism and potential application expansion. Finally, the development prospects of b‐Si photodetectors based on ultrafast laser hyperdoping are predicted.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":"3 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141357089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
U. Yakhnevych, Vanik Sargsyan, F. El Azzouzi, Alexander Kapp, Felix Bernhardt, Y. Suhak, S. Ganschow, H. Schmidt, Simone Sanna, H. Fritze
Lithium niobate‐lithium tantalate solid solutions are new piezoelectric crystals that enable to combine the advantages of their edge compounds with respect to the high thermal stability of lithium tantalate and the high Curie temperature of lithium niobate. This study aims to determine of the acoustic losses of bulk resonators with varying Nb/Ta ratios and their correlation with charge transport at temperatures up to 900 °C and at reduced oxygen partial pressures. Techniques such as resonant piezoelectric spectroscopy and contactless resonant ringdown spectroscopy are used to determine the acoustic losses. Further, the electrical conductivity is determined by impedance spectroscopy. A one‐dimensional physical model for vibrating plates is fitted to the data to extract key parameters such as piezoelectric coefficients and elastic modulus as a function of temperature. Noncontacting determination of loss excludes the impact of metal electrodes and reveals up to 300 °C values in the order of Akhiezer‐type losses. Resonators operated at 2 MHz show a rapid loss increase above about 450 °C, which is attributed to the piezoelectric/carrier relaxation. The latter follows from atomistic models using the key parameters mentioned and the electrical conductivity. The modeling includes variation of the resonance frequency and suggests higher resonance frequencies to lower the acoustic loss.
{"title":"Acoustic Loss in LiNb1−xTaxO3 at Temperatures up to 900 °C","authors":"U. Yakhnevych, Vanik Sargsyan, F. El Azzouzi, Alexander Kapp, Felix Bernhardt, Y. Suhak, S. Ganschow, H. Schmidt, Simone Sanna, H. Fritze","doi":"10.1002/pssa.202400106","DOIUrl":"https://doi.org/10.1002/pssa.202400106","url":null,"abstract":"Lithium niobate‐lithium tantalate solid solutions are new piezoelectric crystals that enable to combine the advantages of their edge compounds with respect to the high thermal stability of lithium tantalate and the high Curie temperature of lithium niobate. This study aims to determine of the acoustic losses of bulk resonators with varying Nb/Ta ratios and their correlation with charge transport at temperatures up to 900 °C and at reduced oxygen partial pressures. Techniques such as resonant piezoelectric spectroscopy and contactless resonant ringdown spectroscopy are used to determine the acoustic losses. Further, the electrical conductivity is determined by impedance spectroscopy. A one‐dimensional physical model for vibrating plates is fitted to the data to extract key parameters such as piezoelectric coefficients and elastic modulus as a function of temperature. Noncontacting determination of loss excludes the impact of metal electrodes and reveals up to 300 °C values in the order of Akhiezer‐type losses. Resonators operated at 2 MHz show a rapid loss increase above about 450 °C, which is attributed to the piezoelectric/carrier relaxation. The latter follows from atomistic models using the key parameters mentioned and the electrical conductivity. The modeling includes variation of the resonance frequency and suggests higher resonance frequencies to lower the acoustic loss.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":" 43","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141368385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Soma Inaba, Weifang Lu, Ayaka Shima, Shiori Ii, Mizuki Takahashi, Yuki Yamanaka, Yuta Hattori, Kosei Kubota, Kai Huang, M. Iwaya, Tetsuya Takeuchi, S. Kamiyama
GaInN/GaN multiple quantum shell (MQS) nanowires (NWs) are of great interest as high‐efficiency micro‐light emitting diodes (micro‐LEDs), mainly due to their quantum confined Stark effect suppression and dry etching insensitivity features. Herein, morphological and device properties corresponding to NW‐LEDs with different numbers of GaInN/GaN superlattices (SLs) are evaluated. The scanning electron microscopy measurements revealed that the polar‐plane MQS are shrunken, while the semipolar‐plane underwent expansion upon the introduction of the SLs. The current density–voltage–light output analysis at low current density indicates that samples with a greater number of SL pairs exhibit higher light output. Electroluminescence spectra show that NWs lacking SLs exhibit an emission wavelength of 700 nm, which is derived from indium‐rich clusters in polar‐plane MQS, whereas those with SLs emit at a significantly shorter wavelength of 560 nm. The reduction in the polar‐plane MQS coupled with the enhancement in MQS quality resulting from the SLs is identified as the primary contributing factor. Additionally, the external quantum efficiency factor for NW‐LEDs, which remained consistent even as the emission area decreased, is assessed. These findings suggest that NW‐LEDs with SLs possess the potential to mitigate the emission degradation associated with sidewall etching and realize high‐efficiency micro‐LEDs.
{"title":"Performance Enhancement of Multiple Quantum Shell Nanowire‐Based Micro‐Light Emitting Diodes with Underlying GaInN/GaN Superlattices","authors":"Soma Inaba, Weifang Lu, Ayaka Shima, Shiori Ii, Mizuki Takahashi, Yuki Yamanaka, Yuta Hattori, Kosei Kubota, Kai Huang, M. Iwaya, Tetsuya Takeuchi, S. Kamiyama","doi":"10.1002/pssa.202400029","DOIUrl":"https://doi.org/10.1002/pssa.202400029","url":null,"abstract":"GaInN/GaN multiple quantum shell (MQS) nanowires (NWs) are of great interest as high‐efficiency micro‐light emitting diodes (micro‐LEDs), mainly due to their quantum confined Stark effect suppression and dry etching insensitivity features. Herein, morphological and device properties corresponding to NW‐LEDs with different numbers of GaInN/GaN superlattices (SLs) are evaluated. The scanning electron microscopy measurements revealed that the polar‐plane MQS are shrunken, while the semipolar‐plane underwent expansion upon the introduction of the SLs. The current density–voltage–light output analysis at low current density indicates that samples with a greater number of SL pairs exhibit higher light output. Electroluminescence spectra show that NWs lacking SLs exhibit an emission wavelength of 700 nm, which is derived from indium‐rich clusters in polar‐plane MQS, whereas those with SLs emit at a significantly shorter wavelength of 560 nm. The reduction in the polar‐plane MQS coupled with the enhancement in MQS quality resulting from the SLs is identified as the primary contributing factor. Additionally, the external quantum efficiency factor for NW‐LEDs, which remained consistent even as the emission area decreased, is assessed. These findings suggest that NW‐LEDs with SLs possess the potential to mitigate the emission degradation associated with sidewall etching and realize high‐efficiency micro‐LEDs.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":" 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141366364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Somsongkul, P. Chirawatkul, Victor Duffort, Soukaina Mountadir, E. Capoen, R. Vannier, C. Kongmark
Energy storage technology plays a critical role in integrating variable energy sources into the grid and ensuring energy consistency. Electrochemical supercapacitors are one of the most promising energy storage devices, as they present multiple advantages of high power density, rapid charge/discharge characteristics, and long‐term cycle stability. Herein, the NiCo2O4/molybdate nanocomposites are developed as electrode materials for supercapacitor applications. The NiCo2O4/molybdate nanocomposites are synthesized by a facile single‐pot hydrothermal method and are coated on a carbon cloth substrate to form flexible supercapacitor electrodes. The structures, chemical compositions, morphologies, and textural properties of these materials are carefully studied by X‐Ray diffraction, X‐Ray absorption spectroscopy, scanning electron microscopy/energy‐dispersive X‐Ray spectroscopy mapping, and N2 adsorption–desorption isotherms. The formation of spinel NiCo2O4 nanorods decorated with molybdate (AMoO4, A = Co, Ni) particles is confirmed for all samples. The NiCo2O4/CoMoO4 electrode exhibits pseudocapacitive behavior and provides the highest specific capacitance (287.28 F g−1 at current density 6 A g−1), about 5.5 times as high as that of NiCo2O4, with excellent cycle stability (107% specific capacitance retention after 1000 charge/discharge cycles at 1 A g−1). Therefore, the NiCo2O4/CoMoO4 composites can be considered as a promising pseudocapacitor electrode material.
储能技术在将可变能源纳入电网和确保能源一致性方面发挥着至关重要的作用。电化学超级电容器具有高功率密度、快速充放电特性和长期循环稳定性等多重优势，是最有前途的储能设备之一。本文开发了镍钴氧化物/钼酸盐纳米复合材料作为超级电容器应用的电极材料。镍钴氧化物/钼酸盐纳米复合材料采用简便的单锅水热法合成，并涂覆在碳布基底上形成柔性超级电容器电极。通过 X 射线衍射、X 射线吸收光谱、扫描电子显微镜/能量色散 X 射线光谱图和 N2 吸附-解吸等温线，对这些材料的结构、化学成分、形态和纹理特性进行了仔细研究。所有样品都证实形成了以钼酸盐（AMoO4，A = Co、Ni）颗粒装饰的尖晶石镍钴氧化物纳米棒。NiCo2O4/CoMoO4 电极表现出假电容行为，提供最高的比电容（电流密度为 6 A g-1 时为 287.28 F g-1），约为 NiCo2O4 的 5.5 倍，并具有出色的循环稳定性（在 1 A g-1 下充放电 1000 次后比电容保持率为 107%）。因此，NiCo2O4/CoMoO4 复合材料可被视为一种前景广阔的伪电容器电极材料。
{"title":"Single‐Step One‐Pot Synthesis of NiCo2O4/Molybdate Nanocomposites for Flexible Supercapacitor Electrodes","authors":"V. Somsongkul, P. Chirawatkul, Victor Duffort, Soukaina Mountadir, E. Capoen, R. Vannier, C. Kongmark","doi":"10.1002/pssa.202400002","DOIUrl":"https://doi.org/10.1002/pssa.202400002","url":null,"abstract":"Energy storage technology plays a critical role in integrating variable energy sources into the grid and ensuring energy consistency. Electrochemical supercapacitors are one of the most promising energy storage devices, as they present multiple advantages of high power density, rapid charge/discharge characteristics, and long‐term cycle stability. Herein, the NiCo2O4/molybdate nanocomposites are developed as electrode materials for supercapacitor applications. The NiCo2O4/molybdate nanocomposites are synthesized by a facile single‐pot hydrothermal method and are coated on a carbon cloth substrate to form flexible supercapacitor electrodes. The structures, chemical compositions, morphologies, and textural properties of these materials are carefully studied by X‐Ray diffraction, X‐Ray absorption spectroscopy, scanning electron microscopy/energy‐dispersive X‐Ray spectroscopy mapping, and N2 adsorption–desorption isotherms. The formation of spinel NiCo2O4 nanorods decorated with molybdate (AMoO4, A = Co, Ni) particles is confirmed for all samples. The NiCo2O4/CoMoO4 electrode exhibits pseudocapacitive behavior and provides the highest specific capacitance (287.28 F g−1 at current density 6 A g−1), about 5.5 times as high as that of NiCo2O4, with excellent cycle stability (107% specific capacitance retention after 1000 charge/discharge cycles at 1 A g−1). Therefore, the NiCo2O4/CoMoO4 composites can be considered as a promising pseudocapacitor electrode material.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":" 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141366854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The in‐plane thermal conductivity of ultra‐thin films is of high interest due to its role in many technological applications, while being very challenging to measure. The challenge lies in creating a heat flow laterally through the thin sample film while eliminating all heat losses to the substrate and the surrounding air. A technique involving two parallel, line‐shaped resistance temperature detectors (RTDs) as a pair of heater and sensor on a nanometer‐thin suspended membrane, which minimizes heat losses to the substrate, has been recently introduced and numerically modeled. Herein, measurements employing two parallel line RTDs on a (164 ± 3) nm thin silicon nitride (SiNx) membrane for characterization of heat flux in electrically conductive polymer films are presented. On top of heater and RTD, silicon dioxide (SiO2) is used as a electrical passivation layer. (118 ± 35) nm poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) thin films are characterized. The methodology to enable these measurements starting from the fabrication of the devices using photolithography and chemical wet etching and the assembly of the high vacuum setup for precise measurements are discussed. Thermal conductivities of 2.9 ± 0.2 W m−1 K−1, 0.6 ± 0.2 W m−1 K−1, and 0.4 ± 0.8 W m−1 K−1 are measured for the SiNx, SiO2 and PEDOT:PSS thin films, respectively. Our findings can facilitate this flexible measurement method to other material systems.
{"title":"Micro‐scale, In‐plane Thermal Conductivity of PEDOT:PSS Thin Films Measured by a Suspended Membrane Device","authors":"Felix Jiang, Mengzhe Ning, Sven Ingebrandt, X. Vu","doi":"10.1002/pssa.202400256","DOIUrl":"https://doi.org/10.1002/pssa.202400256","url":null,"abstract":"The in‐plane thermal conductivity of ultra‐thin films is of high interest due to its role in many technological applications, while being very challenging to measure. The challenge lies in creating a heat flow laterally through the thin sample film while eliminating all heat losses to the substrate and the surrounding air. A technique involving two parallel, line‐shaped resistance temperature detectors (RTDs) as a pair of heater and sensor on a nanometer‐thin suspended membrane, which minimizes heat losses to the substrate, has been recently introduced and numerically modeled. Herein, measurements employing two parallel line RTDs on a (164 ± 3) nm thin silicon nitride (SiNx) membrane for characterization of heat flux in electrically conductive polymer films are presented. On top of heater and RTD, silicon dioxide (SiO2) is used as a electrical passivation layer. (118 ± 35) nm poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) thin films are characterized. The methodology to enable these measurements starting from the fabrication of the devices using photolithography and chemical wet etching and the assembly of the high vacuum setup for precise measurements are discussed. Thermal conductivities of 2.9 ± 0.2 W m−1 K−1, 0.6 ± 0.2 W m−1 K−1, and 0.4 ± 0.8 W m−1 K−1 are measured for the SiNx, SiO2 and PEDOT:PSS thin films, respectively. Our findings can facilitate this flexible measurement method to other material systems.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":" 101","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141374834","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Kornphom, Widchaya Somsri, Sasipohn Prasertpalichat, Bhoowadol Thatawong, C. Kruea-In, Thanya Udeye, A. Rittidech, Chanagon Menkun, N. Vittayakorn, S. Pinitsoontorn, P. Jantaratana, N. Chanlek, T. Bongkarn
Lead‐free (Bi0.5Na0.5)0.7La0.3(Ti0.7Fe0.3)O3 ceramics (abbreviated as BNLTF) are synthesized by the solid‐state combustion technique using glycine as fuel. The effect of the firing temperature (calcined between 700 and 800 °C for 2 h and sintered between at 800 and 900 °C for 2 h) on the phase structure, microstructure, electrical, and magnetic properties is investigated. Pure BNLTF powders are obtained with a calcination temperature of 750 °C for 2 h and the crystal size increases from 47 to 62 nm when the calcination temperature increases from 700 to 800 °C. All sintered BNLTF ceramics show a pure perovskite structure with a rhombohedral phase. The average grain size increases with increasing sintering temperatures. A well‐packed microstructure with the highest density (5.98 g cm−3), good dielectric properties at room temperature (εr ≈ 589 and tanδ ≈ 0.572), soft ferroelectric behavior, and excellent magnetic properties (Ms ≈ 0.091 emu g−1, Mr ≈ 0.0026 emu g−1) is obtained from the ceramic sintered at 875 °C for 2 h. The multiferroic BNLTF ceramic sintered at 875 °C has a maximum magnetoelectric coupling coefficient (αE ≈ 2.08 mV cm−1 Oe−1) when the magnetic field is near 4500 Oe.
{"title":"Improved Dielectric, Magnetic, and Multiferroic Properties of (Bi0.5Na0.5)0.7La0.3(Ti0.7Fe0.3)O3 Ceramics Synthesis by the Solid‐State Combustion Technique","authors":"C. Kornphom, Widchaya Somsri, Sasipohn Prasertpalichat, Bhoowadol Thatawong, C. Kruea-In, Thanya Udeye, A. Rittidech, Chanagon Menkun, N. Vittayakorn, S. Pinitsoontorn, P. Jantaratana, N. Chanlek, T. Bongkarn","doi":"10.1002/pssa.202300989","DOIUrl":"https://doi.org/10.1002/pssa.202300989","url":null,"abstract":"\u0000Lead‐free (Bi0.5Na0.5)0.7La0.3(Ti0.7Fe0.3)O3 ceramics (abbreviated as BNLTF) are synthesized by the solid‐state combustion technique using glycine as fuel. The effect of the firing temperature (calcined between 700 and 800 °C for 2 h and sintered between at 800 and 900 °C for 2 h) on the phase structure, microstructure, electrical, and magnetic properties is investigated. Pure BNLTF powders are obtained with a calcination temperature of 750 °C for 2 h and the crystal size increases from 47 to 62 nm when the calcination temperature increases from 700 to 800 °C. All sintered BNLTF ceramics show a pure perovskite structure with a rhombohedral phase. The average grain size increases with increasing sintering temperatures. A well‐packed microstructure with the highest density (5.98 g cm−3), good dielectric properties at room temperature (εr ≈ 589 and tanδ ≈ 0.572), soft ferroelectric behavior, and excellent magnetic properties (Ms ≈ 0.091 emu g−1, Mr ≈ 0.0026 emu g−1) is obtained from the ceramic sintered at 875 °C for 2 h. The multiferroic BNLTF ceramic sintered at 875 °C has a maximum magnetoelectric coupling coefficient (αE ≈ 2.08 mV cm−1 Oe−1) when the magnetic field is near 4500 Oe.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":" 23","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141375438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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