As‐grown GaN buffer layers have a significant electron concentration, which causes an increase in leakage current and a decrease in the breakdown voltage, VBR, of GaN High Electron Mobility Transistors (HEMTs). To prevent this, deep acceptor traps of density, NAT, are added to the GaN layer during growth. While a study on the effect of NAT on VBR is available in the literature, that on the effect of NAT on contact resistance, Rc, of source/drain contacts is lacking. Herein, the following is established using technology computer‐aided design simulations calibrated with measured current–voltage characteristics of ungated AlGaN/GaN structures: 1) Rc increases significantly with NAT and with the depth of the trap level from the conduction band. For trap level 2.5 eV below the conduction band, Rc doubles for an increase in NAT from 1 × 1016 to 5 × 1017 cm−3. 2) The variation of Rc with temperature is non‐monotonic. Over a temperature range of 300–450 K, Rc is nearly constant with temperature for NAT = 1 × 1016 cm−3 and decreases by 20% for NAT = 5 × 1017 cm−3, when traps are 2.5 eV below the conduction band. Also, the degradation of the transfer and output characteristics of GaN HEMTs due to a notable increase in Rc due to NAT is investigated.
{"title":"Effect of Acceptor Traps in GaN Buffer Layer on Source/Drain Contact Resistance in AlGaN/GaN High Electron Mobility Transistors","authors":"Vijaya Nandini Devi Addagalla, Prasannanjaneyulu Bhavana, Shreepad Karmalkar","doi":"10.1002/pssa.202300950","DOIUrl":"https://doi.org/10.1002/pssa.202300950","url":null,"abstract":"As‐grown GaN buffer layers have a significant electron concentration, which causes an increase in leakage current and a decrease in the breakdown voltage, <jats:italic>V</jats:italic><jats:sub>BR</jats:sub>, of GaN High Electron Mobility Transistors (HEMTs). To prevent this, deep acceptor traps of density, <jats:italic>N</jats:italic><jats:sub>AT</jats:sub>, are added to the GaN layer during growth. While a study on the effect of <jats:italic>N</jats:italic><jats:sub>AT</jats:sub> on <jats:italic>V</jats:italic><jats:sub>BR</jats:sub> is available in the literature, that on the effect of <jats:italic>N</jats:italic><jats:sub>AT</jats:sub> on contact resistance, <jats:italic>R</jats:italic><jats:sub>c</jats:sub>, of source/drain contacts is lacking. Herein, the following is established using technology computer‐aided design simulations calibrated with measured current–voltage characteristics of ungated AlGaN/GaN structures: 1) <jats:italic>R</jats:italic><jats:sub>c</jats:sub> increases significantly with <jats:italic>N</jats:italic><jats:sub>AT</jats:sub> and with the depth of the trap level from the conduction band. For trap level 2.5 eV below the conduction band, <jats:italic>R</jats:italic><jats:sub>c</jats:sub> doubles for an increase in <jats:italic>N</jats:italic><jats:sub>AT</jats:sub> from 1 × 10<jats:sup>16</jats:sup> to 5 × 10<jats:sup>17</jats:sup> cm<jats:sup>−3</jats:sup>. 2) The variation of <jats:italic>R</jats:italic><jats:sub>c</jats:sub> with temperature is non‐monotonic. Over a temperature range of 300–450 K, <jats:italic>R</jats:italic><jats:sub>c</jats:sub> is nearly constant with temperature for <jats:italic>N</jats:italic><jats:sub>AT</jats:sub> = 1 × 10<jats:sup>16</jats:sup> cm<jats:sup>−3</jats:sup> and decreases by 20% for <jats:italic>N</jats:italic><jats:sub>AT</jats:sub> = 5 × 10<jats:sup>17</jats:sup> cm<jats:sup>−3</jats:sup>, when traps are 2.5 eV below the conduction band. Also, the degradation of the transfer and output characteristics of GaN HEMTs due to a notable increase in <jats:italic>R</jats:italic><jats:sub>c</jats:sub> due to <jats:italic>N</jats:italic><jats:sub>AT</jats:sub> is investigated.","PeriodicalId":20074,"journal":{"name":"Physica Status Solidi A-applications and Materials Science","volume":"52 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141518388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Among hydrogen production methods, water electrolysis stands out, but its efficiency is hampered by the substantial energy barrier of the oxygen evolution reaction (OER). To address this, incorporating electron‐deficient boron (B) into Co–Fe hydroxide (CoFeOxHy) promotes higher oxidation states of involved metals, greatly enhancing OER activity and charge transfer capabilities. Herein, the synthesis of a range of amorphous CoFeB nanoparticles with varying Fe to (Co+Fe) atomic ratios achieved through a simple chemical reduction method using CoFe‐Prussian blue analogs as precursors and employing Mössbauer spectroscopy to observe structural characteristics before and after transformation is reported. Among these nanoparticles, the CoFe0.25B variant, exhibiting favorable electrochemical properties, is chosen and subsequently subjected to hydrolysis to yield CoFe0.25BOH nanoparticles, serving as an active catalyst for OER. At a current density of 10 mA cm−2, the overpotentials for CoFe0.25OxHy and CoFe0.25BOH are 362 and 310 mV, respectively, with Tafel slopes decreasing from 393 to 93 mV dec−1. Furthermore, the i–t test reveals no significant loss of electrochemical performance within 24 h, substantiating the efficacy of enhancing the electrocatalytic performance of CoFeOxHy through the introduction of electron‐deficient elements. This research offers novel insights into the development of efficient and stable water electrolysis catalysts.
在制氢方法中，水电解法脱颖而出，但其效率却因氧进化反应（OER）的巨大能量障碍而受到影响。为解决这一问题，在氢氧化钴铁（CoFeOxHy）中加入缺电子硼（B）可促进相关金属的高氧化态，从而大大提高 OER 活性和电荷转移能力。本文以 CoFe-Prussian blue 类似物为前体，通过简单的化学还原方法合成了一系列非晶 CoFeB 纳米粒子，这些粒子具有不同的铁原子比（Co+Fe），并利用莫斯鲍尔光谱观察了转化前后的结构特征。在这些纳米粒子中，CoFe0.25B 变体表现出良好的电化学特性，被选中并随后进行水解，生成 CoFe0.25BOH 纳米粒子，作为 OER 的活性催化剂。在 10 mA cm-2 的电流密度下，CoFe0.25OxHy 和 CoFe0.25BOH 的过电位分别为 362 mV 和 310 mV，Tafel 斜率从 393 mV dec-1 下降到 93 mV dec-1。此外，i-t 测试表明，24 小时内电化学性能没有明显下降，证明了通过引入缺电子元素提高 CoFeOxHy 电催化性能的有效性。这项研究为开发高效稳定的水电解催化剂提供了新的见解。
{"title":"Enhanced Oxygen Evolution Reaction Performance in Co–Fe Hydroxides through Boron Doping","authors":"Peijia Liu, Liang Shan, Zeyi Lu, Min Liu","doi":"10.1002/pssa.202400481","DOIUrl":"https://doi.org/10.1002/pssa.202400481","url":null,"abstract":"Among hydrogen production methods, water electrolysis stands out, but its efficiency is hampered by the substantial energy barrier of the oxygen evolution reaction (OER). To address this, incorporating electron‐deficient boron (B) into Co–Fe hydroxide (CoFeO<jats:sub><jats:italic>x</jats:italic></jats:sub>H<jats:sub><jats:italic>y</jats:italic></jats:sub>) promotes higher oxidation states of involved metals, greatly enhancing OER activity and charge transfer capabilities. Herein, the synthesis of a range of amorphous CoFeB nanoparticles with varying Fe to (Co+Fe) atomic ratios achieved through a simple chemical reduction method using CoFe‐Prussian blue analogs as precursors and employing Mössbauer spectroscopy to observe structural characteristics before and after transformation is reported. Among these nanoparticles, the CoFe<jats:sub>0.25</jats:sub>B variant, exhibiting favorable electrochemical properties, is chosen and subsequently subjected to hydrolysis to yield CoFe<jats:sub>0.25</jats:sub>BOH nanoparticles, serving as an active catalyst for OER. At a current density of 10 mA cm<jats:sup>−2</jats:sup>, the overpotentials for CoFe<jats:sub>0.25</jats:sub>O<jats:sub><jats:italic>x</jats:italic></jats:sub>H<jats:sub><jats:italic>y</jats:italic></jats:sub> and CoFe<jats:sub>0.25</jats:sub>BOH are 362 and 310 mV, respectively, with Tafel slopes decreasing from 393 to 93 mV dec<jats:sup>−1</jats:sup>. Furthermore, the <jats:italic>i</jats:italic>–<jats:italic>t</jats:italic> test reveals no significant loss of electrochemical performance within 24 h, substantiating the efficacy of enhancing the electrocatalytic performance of CoFeO<jats:sub><jats:italic>x</jats:italic></jats:sub>H<jats:sub><jats:italic>y</jats:italic></jats:sub> through the introduction of electron‐deficient elements. This research offers novel insights into the development of efficient and stable water electrolysis catalysts.","PeriodicalId":20074,"journal":{"name":"Physica Status Solidi A-applications and Materials Science","volume":"111 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141518391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A Yb3+‐doped Gd3Al2Ga3O12 garnet (GAGG) Boltzmann thermometer is prepared and studied in this work. Due to the Boltzmann distribution of the population of Stark sublevels of Yb3+, the photoluminescence peaks of Yb3+ in the wavelength range of 950–1000 and 1000–1050 nm exhibit opposite temperature dependencies, which makes the luminescence intensity ratio (LIR) of two Yb3+ peaks work as a luminescence thermometer with a relative sensitivity of 1.6% K−1 at 200 K. It is worth nothing that this LIR value still follows the Arrhenius model at temperatures as low as 200 K. In these results, it is suggested that Yb3+‐doped GAGG thermometer can achieve high sensitivity for accurate temperature measurements. In addition, the accurate position of various Stark sublevels of Yb3+ in GAGG is obtained for the first time. In this work, it is confirmed that the Yb3+‐doped GAGG thermometer exhibits potential applications in the fields of microelectronics and biology.
{"title":"Near‐Infrared Thermometer Based on Stark Energy Levels of Yb3+ in Garnet","authors":"Qixuan Zhang, Jumpei Ueda, Ruilin Zheng, Setsuhisa Tanabe","doi":"10.1002/pssa.202400302","DOIUrl":"https://doi.org/10.1002/pssa.202400302","url":null,"abstract":"A Yb<jats:sup>3+</jats:sup>‐doped Gd<jats:sub>3</jats:sub>Al<jats:sub>2</jats:sub>Ga<jats:sub>3</jats:sub>O<jats:sub>12</jats:sub> garnet (GAGG) Boltzmann thermometer is prepared and studied in this work. Due to the Boltzmann distribution of the population of Stark sublevels of Yb<jats:sup>3+</jats:sup>, the photoluminescence peaks of Yb<jats:sup>3+</jats:sup> in the wavelength range of 950–1000 and 1000–1050 nm exhibit opposite temperature dependencies, which makes the luminescence intensity ratio (LIR) of two Yb<jats:sup>3+</jats:sup> peaks work as a luminescence thermometer with a relative sensitivity of 1.6% K<jats:sup>−1</jats:sup> at 200 K. It is worth nothing that this LIR value still follows the Arrhenius model at temperatures as low as 200 K. In these results, it is suggested that Yb<jats:sup>3+</jats:sup>‐doped GAGG thermometer can achieve high sensitivity for accurate temperature measurements. In addition, the accurate position of various Stark sublevels of Yb<jats:sup>3+</jats:sup> in GAGG is obtained for the first time. In this work, it is confirmed that the Yb<jats:sup>3+</jats:sup>‐doped GAGG thermometer exhibits potential applications in the fields of microelectronics and biology.","PeriodicalId":20074,"journal":{"name":"Physica Status Solidi A-applications and Materials Science","volume":"3 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141531309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, a nitride‐based blue PEDOT‐LED is fabricated and a preliminary assessment of the device characteristics is done. To prevent detaching of the PEDOT/PSS layer from the LED substrate when immersing in water or developing solution, Ag was deposited on top of the PEDOT/PSS layer. Additionally, exfoliation is suppressed by reducing the developing time and protecting the wafer edge with a photoresist. Different etching methods for Ag and PEDOT/PSS are investigated. The Ar ion‐beam etching resulted in uniform and flat‐etched surfaces. Regarding the performance of the PEDOT‐LEDs, a high Mg‐doping concentration of 1.0 × 1020 cm−2 leads to a relatively low threshold current voltage in the V–I characteristics. However, for the PEDOT‐LED with p‐Al0.25Ga0.75 N EBL, a steep light output saturation is observed at high current density when analyzing the L–I characteristics.
本研究制作了氮化物基蓝色 PEDOT-LED 并对器件特性进行了初步评估。为防止 PEDOT/PSS 层在浸入水或显影溶液时从 LED 基底上剥离，在 PEDOT/PSS 层顶部沉积了银。此外，还通过缩短显影时间和使用光致抗蚀剂保护晶片边缘来抑制剥离。研究了针对 Ag 和 PEDOT/PSS 的不同蚀刻方法。氩离子束蚀刻可获得均匀平整的蚀刻表面。关于 PEDOT-LED 的性能，1.0 × 1020 cm-2 的高镁掺杂浓度导致 V-I 特性的阈值电流电压相对较低。然而，对于采用 p-Al0.25Ga0.75 N EBL 的 PEDOT-LED 来说，在分析 L-I 特性时，会发现在高电流密度下会出现陡峭的光输出饱和。
{"title":"GaInN‐Based Blue LED with a PEDOT/PSS Hole Transport Layer","authors":"Yuma Kato, Motoaki Iwaya, Tetsuya Takeuchi, Satoshi Kamiyama","doi":"10.1002/pssa.202400090","DOIUrl":"https://doi.org/10.1002/pssa.202400090","url":null,"abstract":"In this study, a nitride‐based blue PEDOT‐LED is fabricated and a preliminary assessment of the device characteristics is done. To prevent detaching of the PEDOT/PSS layer from the LED substrate when immersing in water or developing solution, Ag was deposited on top of the PEDOT/PSS layer. Additionally, exfoliation is suppressed by reducing the developing time and protecting the wafer edge with a photoresist. Different etching methods for Ag and PEDOT/PSS are investigated. The Ar ion‐beam etching resulted in uniform and flat‐etched surfaces. Regarding the performance of the PEDOT‐LEDs, a high Mg‐doping concentration of 1.0 × 10<jats:sup>20</jats:sup> cm<jats:sup>−2</jats:sup> leads to a relatively low threshold current voltage in the V–I characteristics. However, for the PEDOT‐LED with <jats:italic>p</jats:italic>‐Al0.25Ga0.75 N EBL, a steep light output saturation is observed at high current density when analyzing the L–I characteristics.","PeriodicalId":20074,"journal":{"name":"Physica Status Solidi A-applications and Materials Science","volume":"67 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141531308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The aim is to develop highly efficient GaInN/GaN nanowire (NW)‐based light‐emitting diodes (LEDs), which are composed of GaN NWs and multiquantum shell (MQS) active regions. These regions incorporate the polar c‐plane, nonpolar r‐plane, and semipolar m‐plane. A challenge with MQS‐LEDs is that the current path through the c‐plane MQS tends to dominate under low‐current injection conditions. Given that the MQS on the c‐plane is very defective, this injection current is mainly subjected to nonradiative recombination. Therefore, this study explores various optimizations of the p‐AlGaN electron blocking layers (EBLs) to minimize the current injection into the MQS in the c‐plane region. The samples are subsequently grown using a specific process. This involves n‐GaN NWs, GaInN/GaN‐based quantum shells, p‐AlGaN EBLs with different Al compositions, and p‐GaN shells. All these are developed by metal–organic vapor phase epitaxy on an n‐GaN template featuring a SiO2 hole pattern. NW LEDs are fabricated and subsequently their device characteristics are investigated. Under low‐current injection, the sample with a lower Al composition exhibits higher luminescence intensity. However, this trend reverses when the injection current increases. The findings suggest that AI composition and thickness in the p‐AlGaN EBL significantly affect the output power and the emission wavelength.
我们的目标是开发基于氮化镓/氮化镓纳米线 (NW) 的高效发光二极管 (LED)，这种二极管由氮化镓纳米线和多量子壳 (MQS) 有源区组成。这些区域包括极性 c 平面、非极性 r 平面和半极性 m 平面。MQS-LED 面临的一个挑战是，在低电流注入条件下，通过 c 平面 MQS 的电流路径往往占主导地位。由于 c 平面上的 MQS 缺陷很大，注入电流主要受非辐射重组的影响。因此，本研究对 p-AlGaN 电子阻挡层 (EBL) 进行了各种优化，以尽量减少注入 c 平面区域 MQS 的电流。样品随后采用特定工艺生长。这涉及 n-GaN NW、基于 GaInN/GaN 的量子壳、不同铝成分的 pAlGaN EBL 和 p-GaN 壳。所有这些都是通过在具有二氧化硅孔图案的 n-GaN 模板上进行金属有机气相外延而形成的。NW LED 制作完成后，对其器件特性进行了研究。在低电流注入条件下，铝成分较低的样品表现出较高的发光强度。然而，当注入电流增大时，这一趋势发生逆转。研究结果表明，p-AlGaN EBL 中的 AI 成分和厚度会显著影响输出功率和发射波长。
{"title":"Optimization of the Al Composition of the p‐AlGaN Electron Blocking Layer in GaInN/GaN Multiquantum‐Shell Nanowire LEDs","authors":"Yuta Hattori, Weifang Lu, Soma Inaba, Ayaka Shima, Shiori Ii, Mizuki Takahashi, Yuki Yamanaka, Kosei Kubota, Satoshi Kamiyama, Tetsuya Takeuchi, Motoaki Iwaya","doi":"10.1002/pssa.202400116","DOIUrl":"https://doi.org/10.1002/pssa.202400116","url":null,"abstract":"The aim is to develop highly efficient GaInN/GaN nanowire (NW)‐based light‐emitting diodes (LEDs), which are composed of GaN NWs and multiquantum shell (MQS) active regions. These regions incorporate the polar c‐plane, nonpolar r‐plane, and semipolar m‐plane. A challenge with MQS‐LEDs is that the current path through the c‐plane MQS tends to dominate under low‐current injection conditions. Given that the MQS on the c‐plane is very defective, this injection current is mainly subjected to nonradiative recombination. Therefore, this study explores various optimizations of the p‐AlGaN electron blocking layers (EBLs) to minimize the current injection into the MQS in the c‐plane region. The samples are subsequently grown using a specific process. This involves n‐GaN NWs, GaInN/GaN‐based quantum shells, p‐AlGaN EBLs with different Al compositions, and p‐GaN shells. All these are developed by metal–organic vapor phase epitaxy on an n‐GaN template featuring a SiO<jats:sub>2</jats:sub> hole pattern. NW LEDs are fabricated and subsequently their device characteristics are investigated. Under low‐current injection, the sample with a lower Al composition exhibits higher luminescence intensity. However, this trend reverses when the injection current increases. The findings suggest that AI composition and thickness in the p‐AlGaN EBL significantly affect the output power and the emission wavelength.","PeriodicalId":20074,"journal":{"name":"Physica Status Solidi A-applications and Materials Science","volume":"82 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141518305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A theoretical study of a one‐dimensional photonic crystal (1D‐PhC) [TiO2/MgF2]2/TiO2/GaAs terminated by a dielectric metasurface consisting of periodically arranged TiO2 nanospheres for biosensing is proposed. The p polarized incident beam and the prism couplingtechnique are employed to excite Bloch surface waves considering a low biomolecular concentration sensing medium with refractive index changing from 1.33 to 1.34 RIU. The optical properties of the metasurface layer are calculated within the effective medium approximation. The findings reveal that integrating TiO2 nanosphere metasurfaces as the upper layer of a photonic structure allows simultaneous control of biosensor sensitivity and the reflectance curve's full width at half maximum by judiciously tuning its optical properties, relying on the filling fraction (f) and the size () of the TiO2 nanospheres. Moreover, The results show that the biosensor with the metasurface performs superior to the one without it.
本文提出了用于生物传感的一维光子晶体（1D-PhC）[TiO2/MgF2]2/TiO2/GaAs 的理论研究，该晶体由周期性排列的 TiO2 纳米球组成的介电元表面终止。考虑到低生物分子浓度传感介质的折射率在 1.33 到 1.34 RIU 之间变化，采用了 p 偏振入射光束和棱镜耦合技术来激发布洛赫表面波。在有效介质近似条件下计算了元表层的光学特性。研究结果表明，将二氧化钛纳米球元表层作为光子结构的上层，可以根据二氧化钛纳米球的填充分数（f）和尺寸（），通过明智地调整其光学特性，同时控制生物传感器的灵敏度和反射曲线的半最大全宽。此外，研究结果表明，有元表面的生物传感器比没有元表面的生物传感器性能更好。
{"title":"High Bloch Surface Waves’ Biosensor Sensitivity Using All‐Dielectric Metasurface","authors":"Malika Chikhi, Louhadj Amina, Fouzia Boukabrine, Nadia Benseddik, Fouad Talbi","doi":"10.1002/pssa.202400259","DOIUrl":"https://doi.org/10.1002/pssa.202400259","url":null,"abstract":"A theoretical study of a one‐dimensional photonic crystal (1D‐PhC) [TiO<jats:sub>2</jats:sub>/MgF<jats:sub>2</jats:sub>]<jats:sub>2</jats:sub>/TiO<jats:sub>2</jats:sub>/GaAs terminated by a dielectric metasurface consisting of periodically arranged TiO<jats:sub>2</jats:sub> nanospheres for biosensing is proposed. The p polarized incident beam and the prism couplingtechnique are employed to excite Bloch surface waves considering a low biomolecular concentration sensing medium with refractive index changing from 1.33 to 1.34 RIU. The optical properties of the metasurface layer are calculated within the effective medium approximation. The findings reveal that integrating TiO<jats:sub>2</jats:sub> nanosphere metasurfaces as the upper layer of a photonic structure allows simultaneous control of biosensor sensitivity and the reflectance curve's full width at half maximum by judiciously tuning its optical properties, relying on the filling fraction (<jats:italic>f</jats:italic>) and the size () of the TiO<jats:sub>2</jats:sub> nanospheres. Moreover, The results show that the biosensor with the metasurface performs superior to the one without it.","PeriodicalId":20074,"journal":{"name":"Physica Status Solidi A-applications and Materials Science","volume":"48 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141531310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aina Hiyama Zazuli, Taketo Kowaki, Minagi Miyamoto, Koki Hanasaku, Daisuke Inahara, Kai Fujii, Satoshi Kurai, Narihito Okada, Yoichi Yamada
The metal‐organic vapor phase epitaxy (MOVPE) method faces several challenges when used for the growth of N‐polar GaN on foreign substrates, including the presence of a rough surface morphology characterized by step bunching or hexagonal hillocks. In this study, it is aimed to address these issues by establishing optimal growth conditions for the MOVPE method, enabling the growth of N‐polar GaN/Al0.9Ga0.1N/AlN heterostructures with a smooth surface morphology on a vicinal sapphire substrate. The formation of 2D electron gas (2DEG) in N‐polar GaN/AlGaN/AlN prepared using MOVPE is discussed. Additionally, in the study, the impact of growth conditions, such as temperature and V/III ratio, on the electrical properties of N‐polar GaN is investigated. In the results, it is revealed that growth at lower temperatures and a V/III ratio of 30 000 effectively suppresses 3D growth. Moreover, an increase in the V/III ratio correlates with a decrease in residual impurity concentrations (C and H); hence, electron mobility improves. Moreover, the N‐polar GaN/AlGaN/AlN field‐effect transistor, grown under optimized conditions, exhibits a higher maximum drain–source current (IDmax). In these results, possibilities are broadened for the high performance of N‐polar GaN channel high‐electron‐mobility transistors through MOVPE.
金属有机气相外延（MOVPE）方法用于在外来衬底上生长 N 极 GaN 时面临着一些挑战，包括存在以阶梯束或六角丘为特征的粗糙表面形貌。本研究旨在通过建立 MOVPE 方法的最佳生长条件来解决这些问题，从而使 N 极 GaN/Al0.9Ga0.1N/AlN 异质结构能在沧桑的蓝宝石衬底上生长出具有光滑表面形态的异质结构。研究讨论了在使用 MOVPE 制备的 N 极 GaN/AlGaN/AlN 中形成的二维电子气 (2DEG)。此外，研究还探讨了温度和 V/III 比率等生长条件对 N 极 GaN 电性能的影响。研究结果表明，在较低温度和 V/III 比率为 30 000 的条件下生长可有效抑制三维生长。此外，V/III 比率的增加与残留杂质浓度（C 和 H）的降低相关，因此电子迁移率得到改善。此外，在优化条件下生长的 N 极 GaN/AlGaN/AlN 场效应晶体管显示出更高的最大漏极-源极电流（IDmax）。这些结果拓宽了通过 MOVPE 实现高性能 N 极 GaN 沟道高电子迁移率晶体管的可能性。
{"title":"Electrical Properties of N‐Polar GaN/AlGaN/AlN Grown via Metal‐Organic Vapor Phase Epitaxy","authors":"Aina Hiyama Zazuli, Taketo Kowaki, Minagi Miyamoto, Koki Hanasaku, Daisuke Inahara, Kai Fujii, Satoshi Kurai, Narihito Okada, Yoichi Yamada","doi":"10.1002/pssa.202400060","DOIUrl":"https://doi.org/10.1002/pssa.202400060","url":null,"abstract":"The metal‐organic vapor phase epitaxy (MOVPE) method faces several challenges when used for the growth of N‐polar GaN on foreign substrates, including the presence of a rough surface morphology characterized by step bunching or hexagonal hillocks. In this study, it is aimed to address these issues by establishing optimal growth conditions for the MOVPE method, enabling the growth of N‐polar GaN/Al<jats:sub>0.9</jats:sub>Ga<jats:sub>0.1</jats:sub>N/AlN heterostructures with a smooth surface morphology on a vicinal sapphire substrate. The formation of 2D electron gas (2DEG) in N‐polar GaN/AlGaN/AlN prepared using MOVPE is discussed. Additionally, in the study, the impact of growth conditions, such as temperature and V/III ratio, on the electrical properties of N‐polar GaN is investigated. In the results, it is revealed that growth at lower temperatures and a V/III ratio of 30 000 effectively suppresses 3D growth. Moreover, an increase in the V/III ratio correlates with a decrease in residual impurity concentrations (C and H); hence, electron mobility improves. Moreover, the N‐polar GaN/AlGaN/AlN field‐effect transistor, grown under optimized conditions, exhibits a higher maximum drain–source current (<jats:italic>I</jats:italic><jats:sub>Dmax</jats:sub>). In these results, possibilities are broadened for the high performance of N‐polar GaN channel high‐electron‐mobility transistors through MOVPE.","PeriodicalId":20074,"journal":{"name":"Physica Status Solidi A-applications and Materials Science","volume":"8 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141496155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jian Cheng, Xin Liu, Weichang Kong, Qingzheng Lei, Zhiyu Yu, Dun Liu
The fabrication of flexible electronics has gained extensive attention due to the growing demand of flexible devices. Among various methods, laser direct writing technology has emerged as a promising approach due to its advantages of high processing accuracy and simplicity. This research focuses on the preparation of copper microelectrodes using laser‐induced reduction of CuO nanoparticles (Cu NPs) on polyethylene terephthalate films. First, the influence of various parameters on the conductivity of the copper microelectrodes is investigated. Second, flexible copper microelectrodes with a minimum resistivity of 62.29 μΩ cm and an adhesion grade of 4B level are successfully fabricated. Building upon these results, a capacitive pressure sensor is developed with optimal sensitivity of 3.99 Pa−1, good hysteresis of 3.99%, and response and recovery times of 1.2 and 1.3 s, respectively. Repeatability tests confirm the sensor's stability and fatigue resistance. This research provides valuable insights for the production of flexible sensors.
{"title":"Fabrication of Flexible Copper Microelectrodes Using Laser Direct Writing for Sensing Applications","authors":"Jian Cheng, Xin Liu, Weichang Kong, Qingzheng Lei, Zhiyu Yu, Dun Liu","doi":"10.1002/pssa.202400342","DOIUrl":"https://doi.org/10.1002/pssa.202400342","url":null,"abstract":"The fabrication of flexible electronics has gained extensive attention due to the growing demand of flexible devices. Among various methods, laser direct writing technology has emerged as a promising approach due to its advantages of high processing accuracy and simplicity. This research focuses on the preparation of copper microelectrodes using laser‐induced reduction of CuO nanoparticles (Cu NPs) on polyethylene terephthalate films. First, the influence of various parameters on the conductivity of the copper microelectrodes is investigated. Second, flexible copper microelectrodes with a minimum resistivity of 62.29 μΩ cm and an adhesion grade of 4B level are successfully fabricated. Building upon these results, a capacitive pressure sensor is developed with optimal sensitivity of 3.99 Pa<jats:sup>−1</jats:sup>, good hysteresis of 3.99%, and response and recovery times of 1.2 and 1.3 s, respectively. Repeatability tests confirm the sensor's stability and fatigue resistance. This research provides valuable insights for the production of flexible sensors.","PeriodicalId":20074,"journal":{"name":"Physica Status Solidi A-applications and Materials Science","volume":"2015 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141496156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiangying Xue, Weichuang Yang, Zhiqin Ying, Yuheng Zeng, Xi Yang, Jichun Ye
Organic–inorganic hybrid perovskites in combination with the hole‐transport material (HTM) 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluoren (spiro‐OMeTAD) yield impressive power conversion efficiency (PCE) in n–i–p perovskite solar cells (PSC). To ensure sufficient hole extraction from the perovskite absorber to the metal electrode, the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) doping is considered indispensable to promote spiro‐OMeTAD oxidization and obtain consequently enhanced conductivity. However, LiTFSI‐doped spiro‐OMeTAD usually leads to a reduced stability of PSCs because of the hygroscopic nature of LiTFSI, which further limits its potential commercialization. Herein, a hydrophobic material, namely perfluoropolyethers (PFPEs), is used as surface modifier of doped HTM to improve both efficiency and stability of PSCs. It is revealed that the introduction of PFPE increases the concentration of positive radicals, enhances charge‐carrier transport, and improves stability of PSCs under wetting stress. Moreover, the device based on PFPE achieves a champion PCE of 21.94%. In these findings, valuable insights are provided for the future commercialization of PSCs.
{"title":"Stabilizing Perovskite Solar Cells Based on 2,2′,7,7′‐Tetrakis(N,N‐DI‐P‐Methoxyphenylamine)‐9,9′‐Spirobifluoren with Perfluoropolyethers","authors":"Xiangying Xue, Weichuang Yang, Zhiqin Ying, Yuheng Zeng, Xi Yang, Jichun Ye","doi":"10.1002/pssa.202400390","DOIUrl":"https://doi.org/10.1002/pssa.202400390","url":null,"abstract":"Organic–inorganic hybrid perovskites in combination with the hole‐transport material (HTM) 2,2′,7,7′‐tetrakis(N,N‐di‐<jats:italic>p</jats:italic>‐methoxyphenylamine)‐9,9′‐spirobifluoren (spiro‐OMeTAD) yield impressive power conversion efficiency (PCE) in n–i–p perovskite solar cells (PSC). To ensure sufficient hole extraction from the perovskite absorber to the metal electrode, the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) doping is considered indispensable to promote spiro‐OMeTAD oxidization and obtain consequently enhanced conductivity. However, LiTFSI‐doped spiro‐OMeTAD usually leads to a reduced stability of PSCs because of the hygroscopic nature of LiTFSI, which further limits its potential commercialization. Herein, a hydrophobic material, namely perfluoropolyethers (PFPEs), is used as surface modifier of doped HTM to improve both efficiency and stability of PSCs. It is revealed that the introduction of PFPE increases the concentration of positive radicals, enhances charge‐carrier transport, and improves stability of PSCs under wetting stress. Moreover, the device based on PFPE achieves a champion PCE of 21.94%. In these findings, valuable insights are provided for the future commercialization of PSCs.","PeriodicalId":20074,"journal":{"name":"Physica Status Solidi A-applications and Materials Science","volume":"3 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141500605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The present research describes the optical, structural, dielectric, photocatalytic, and antibacterial characteristics of potassium‐doped ZnO thin films synthesized via sol–gel dip coating technique with a K doping concentration of (1, 2, 3, 4, 5) wt%. Thin films are annealed at optimized temperatures. K‐doped ZnO has a hexagonal wurtzite phase having a preferential orientation along the (101) plane. The size of the crystallite decreases as the potassium doping percentage rises. Optical analysis reveals that the bandgap decreases when the quantity of K doping in ZnO increases. Dielectric constant experiments show that when the K doping % is raised, AC conductivity of thin films rises as well. Thin film resistivity and Hall coefficient decrease with increasing K concentration, but conductivity, mobility, and carrier concentration rise. Gram‐positive and gram‐negative bacteria are both responsive to K‐doped ZnO. With such antibacterial properties, K‐doped ZnO can be used in biomedicine and to protect the environment. The methylene blue dye is effectively degraded by the photocatalyst K‐doped ZnO, making it useful for removing pollution from wastewater.
本研究介绍了通过溶胶-凝胶浸涂技术合成的钾掺杂氧化锌薄膜的光学、结构、介电、光催化和抗菌特性，钾掺杂浓度为 (1, 2, 3, 4, 5) wt%。薄膜在最佳温度下退火。掺杂了 K 的氧化锌具有六方菱面体相，并沿 (101) 平面优先取向。随着钾掺杂百分比的增加，晶粒尺寸也随之减小。光学分析表明，当氧化锌中的钾掺杂量增加时，带隙会减小。介电常数实验表明，当钾掺杂百分比增加时，薄膜的交流电导率也会增加。薄膜电阻率和霍尔系数随 K 浓度的增加而降低，但电导率、迁移率和载流子浓度却上升了。革兰氏阳性和革兰氏阴性细菌对掺杂 K 的氧化锌都有反应。掺 K 氧化锌具有这种抗菌特性，可用于生物医学和环境保护。光催化剂 K 掺杂氧化锌能有效降解亚甲基蓝染料，因此可用于去除废水中的污染。
{"title":"Nanostructured K‐Doped ZnO Thin Films: Synthesis and Investigations","authors":"Zohra Nazir Kayani, Ayesha Akram, Zainab Bashir, Salma Waseem, Saira Riaz, Shahzad Naseem","doi":"10.1002/pssa.202300982","DOIUrl":"https://doi.org/10.1002/pssa.202300982","url":null,"abstract":"The present research describes the optical, structural, dielectric, photocatalytic, and antibacterial characteristics of potassium‐doped ZnO thin films synthesized via sol–gel dip coating technique with a K doping concentration of (1, 2, 3, 4, 5) wt%. Thin films are annealed at optimized temperatures. K‐doped ZnO has a hexagonal wurtzite phase having a preferential orientation along the (101) plane. The size of the crystallite decreases as the potassium doping percentage rises. Optical analysis reveals that the bandgap decreases when the quantity of K doping in ZnO increases. Dielectric constant experiments show that when the K doping % is raised, AC conductivity of thin films rises as well. Thin film resistivity and Hall coefficient decrease with increasing K concentration, but conductivity, mobility, and carrier concentration rise. Gram‐positive and gram‐negative bacteria are both responsive to K‐doped ZnO. With such antibacterial properties, K‐doped ZnO can be used in biomedicine and to protect the environment. The methylene blue dye is effectively degraded by the photocatalyst K‐doped ZnO, making it useful for removing pollution from wastewater.","PeriodicalId":20074,"journal":{"name":"Physica Status Solidi A-applications and Materials Science","volume":"32 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141518394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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