The one‐step green synthesis of wide band gap zinc oxide@zinc sulfide (ZnO@ZnS) core–shell nanostructures offers promising prospects in wastewater treatment. These nanostructures exhibit a porous nature crucial for effective dye adsorption, as evidenced by Brunauer‐Emmett‐Teller (BET) and microscopic characterization. The synthesized material demonstrates high stability and minimal agglomeration, verified through BET analysis and zeta potential measurements. X‐ray powder diffraction confirms the presence of ZnO and ZnS phases. Transmission electron microscopy reveals the development of porous nanorods on the core surface, maximizing the surface area for dye adsorption. In wastewater treatment, the nanostructures exhibit notable performance, degrading 90% of malachite green and 50% of rhodamine B dyes within 120 min under normal conditions. Detailed discussions delve into the degradation mechanism, elucidating the major species responsible for the process. This study underscores the potential of ZnO@ZnS nanostructures in efficient organic pollutant removal, marking a significant advancement in environmental remediation.
一步法绿色合成宽带隙氧化锌@硫化锌（ZnO@ZnS）核壳纳米结构为废水处理提供了广阔的前景。这些纳米结构具有多孔性，对有效吸附染料至关重要，布鲁纳-艾美特-泰勒（BET）和显微表征证明了这一点。通过 BET 分析和 zeta 电位测量，合成材料表现出高度的稳定性和最小的团聚。X 射线粉末衍射证实了 ZnO 和 ZnS 相的存在。透射电子显微镜显示，核心表面形成了多孔纳米棒，使染料吸附的表面积最大化。在废水处理中，纳米结构表现出显著的性能，在正常条件下，120 分钟内可降解 90% 的孔雀石绿和 50% 的罗丹明 B 染料。详细的讨论深入探讨了降解机理，阐明了降解过程中的主要物种。这项研究强调了 ZnO@ZnS 纳米结构在高效去除有机污染物方面的潜力，标志着环境修复领域的重大进展。
{"title":"Photocatalytic Performance of ZnO@ZnS Core–Shell Heterostructures for Malachite Green and Rhodamine B Dye Degradation","authors":"Peeyush Phogat, Shreya, Ranjana Jha, Sukhvir Singh","doi":"10.1002/pssa.202400404","DOIUrl":"https://doi.org/10.1002/pssa.202400404","url":null,"abstract":"The one‐step green synthesis of wide band gap zinc oxide@zinc sulfide (ZnO@ZnS) core–shell nanostructures offers promising prospects in wastewater treatment. These nanostructures exhibit a porous nature crucial for effective dye adsorption, as evidenced by Brunauer‐Emmett‐Teller (BET) and microscopic characterization. The synthesized material demonstrates high stability and minimal agglomeration, verified through BET analysis and zeta potential measurements. X‐ray powder diffraction confirms the presence of ZnO and ZnS phases. Transmission electron microscopy reveals the development of porous nanorods on the core surface, maximizing the surface area for dye adsorption. In wastewater treatment, the nanostructures exhibit notable performance, degrading 90% of malachite green and 50% of rhodamine B dyes within 120 min under normal conditions. Detailed discussions delve into the degradation mechanism, elucidating the major species responsible for the process. This study underscores the potential of ZnO@ZnS nanostructures in efficient organic pollutant removal, marking a significant advancement in environmental remediation.","PeriodicalId":506741,"journal":{"name":"physica status solidi (a)","volume":"19 25","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141817439","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}
Shahbaz Afzal, Muhammad Usman, Aamenah Siddiqui, R. Y. Khosa, Anders Hallén
Atomic layer deposited (ALD) TiO2 layers are implanted with N, O, and Ar ions to reduce the bandgap, thereby increasing its absorbance in the visible region. The implantation is accomplished with 40 keV nitrogen, 45 keV oxygen, and 110 keV argon ions in the fluence range 1 × 1015 to 5.6 × 1016 ions cm−2. The energy of each incident ion is tuned using stopping and range of ions in matter (SRIM) to produce defects around the same projected range. The structural analysis of the as‐deposited film is performed through X‐ray diffraction (XRD), scanning electron microscopy (SEM), Rutherford backscattering (RBS), and time of flight elastic recoil detection analysis (ToF‐ERDA). The implanted layers are characterized using diffuse reflectance spectroscopy (DRS) and Fourier transform infrared spectroscopy (FTIR) to study the optical and vibrational properties of the films. The results demonstrate that nitrogen implantation in TiO2 reduces the reflectance from 43.52% to 26.31% and bandgap from 2.68 to 2.61 eV, making it a promising bandgap‐engineered material for capping layers in solar cell applications. The refractive index of the 40 keV nitrogen ion implanted film at 1 × 1016 ions cm−2 (N‐16) increases from ≈2.8 to ≈2.95. OPAL2 solar cell simulations show that the N‐16 implanted TiO2 anti‐reflective coatings (ARC) can enhance the absorbed photocurrent by 7.3%.
{"title":"Ion Implantation‐Induced Bandgap Modifications in the ALD TiO2 Thin Films","authors":"Shahbaz Afzal, Muhammad Usman, Aamenah Siddiqui, R. Y. Khosa, Anders Hallén","doi":"10.1002/pssa.202400205","DOIUrl":"https://doi.org/10.1002/pssa.202400205","url":null,"abstract":"\u0000Atomic layer deposited (ALD) TiO2 layers are implanted with N, O, and Ar ions to reduce the bandgap, thereby increasing its absorbance in the visible region. The implantation is accomplished with 40 keV nitrogen, 45 keV oxygen, and 110 keV argon ions in the fluence range 1 × 1015 to 5.6 × 1016 ions cm−2. The energy of each incident ion is tuned using stopping and range of ions in matter (SRIM) to produce defects around the same projected range. The structural analysis of the as‐deposited film is performed through X‐ray diffraction (XRD), scanning electron microscopy (SEM), Rutherford backscattering (RBS), and time of flight elastic recoil detection analysis (ToF‐ERDA). The implanted layers are characterized using diffuse reflectance spectroscopy (DRS) and Fourier transform infrared spectroscopy (FTIR) to study the optical and vibrational properties of the films. The results demonstrate that nitrogen implantation in TiO2 reduces the reflectance from 43.52% to 26.31% and bandgap from 2.68 to 2.61 eV, making it a promising bandgap‐engineered material for capping layers in solar cell applications. The refractive index of the 40 keV nitrogen ion implanted film at 1 × 1016 ions cm−2 (N‐16) increases from ≈2.8 to ≈2.95. OPAL2 solar cell simulations show that the N‐16 implanted TiO2 anti‐reflective coatings (ARC) can enhance the absorbed photocurrent by 7.3%.","PeriodicalId":506741,"journal":{"name":"physica status solidi (a)","volume":"44 14","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141648784","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}
Interdigitated heterojunction (IHJ) structures have recently been investigated as an alternatives to bulk heterojunction (BHJ) structures due to their better film morphology stability, reproducibility, and contact selectivity. Herein, the electrical and optical properties of a nonfullerene IHJ structure are investigated using drift diffusion and Maxwell equations and compared with other conventional structures. Based on simulation results, the IHJ structure demonstrates electrical advantages such as enhanced charge transport pathways and reduced nonradiative recombination and exhibits superior optical absorption profiles compared to the BHJ structure, owing to its photonic crystal‐like structure. A method is also proposed to further enhance the optical absorption of this structure by introducing a third organic material with absorption capabilities in the near‐infrared range, increasing the solar cell power conversion efficiency from 18.42% to over 19.5%.
{"title":"Enhancing Charge Generation in Nonfullerene Interdigitated Heterojunction Organic Solar Cells","authors":"Roya Salamatbakhsh, Davoud Raeyani, Asghar Asgari","doi":"10.1002/pssa.202400364","DOIUrl":"https://doi.org/10.1002/pssa.202400364","url":null,"abstract":"Interdigitated heterojunction (IHJ) structures have recently been investigated as an alternatives to bulk heterojunction (BHJ) structures due to their better film morphology stability, reproducibility, and contact selectivity. Herein, the electrical and optical properties of a nonfullerene IHJ structure are investigated using drift diffusion and Maxwell equations and compared with other conventional structures. Based on simulation results, the IHJ structure demonstrates electrical advantages such as enhanced charge transport pathways and reduced nonradiative recombination and exhibits superior optical absorption profiles compared to the BHJ structure, owing to its photonic crystal‐like structure. A method is also proposed to further enhance the optical absorption of this structure by introducing a third organic material with absorption capabilities in the near‐infrared range, increasing the solar cell power conversion efficiency from 18.42% to over 19.5%.","PeriodicalId":506741,"journal":{"name":"physica status solidi (a)","volume":"22 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141648952","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}
Andrey Okhapkin, Mikhail Drozdov, Pavel Yunin, Stanislav Kraev, Sergey Korolyov, Dmitry Radishev
Multilayer films of diamond‐like carbon (DLC) on monocrystalline diamond substrates have been for the first time obtained by plasma‐chemical deposition. Their chemical composition and structural and morphological properties are studied. The DLC individual layers differ in their sp3 carbon content. The multilayer nature of the resulting coatings is confirmed by periodic density modulation on the small‐angle X‐ray reflectometry curve and modulations in the CsC8, CsC6, CsC4 lines on the crater depth profile of secondary ions of elements (secondary ion mass spectrometry). The dependence of the deposition rate of multilayer DLC films on diamond, their composition and properties on the argon additive to the reaction gas mixture, as well as on methane flow, pressure and growth time, are studied.
{"title":"Multilayer Diamond‐Like Carbon Films on Monocrystalline Diamond","authors":"Andrey Okhapkin, Mikhail Drozdov, Pavel Yunin, Stanislav Kraev, Sergey Korolyov, Dmitry Radishev","doi":"10.1002/pssa.202400345","DOIUrl":"https://doi.org/10.1002/pssa.202400345","url":null,"abstract":"\u0000Multilayer films of diamond‐like carbon (DLC) on monocrystalline diamond substrates have been for the first time obtained by plasma‐chemical deposition. Their chemical composition and structural and morphological properties are studied. The DLC individual layers differ in their sp3 carbon content. The multilayer nature of the resulting coatings is confirmed by periodic density modulation on the small‐angle X‐ray reflectometry curve and modulations in the CsC8, CsC6, CsC4 lines on the crater depth profile of secondary ions of elements (secondary ion mass spectrometry). The dependence of the deposition rate of multilayer DLC films on diamond, their composition and properties on the argon additive to the reaction gas mixture, as well as on methane flow, pressure and growth time, are studied.","PeriodicalId":506741,"journal":{"name":"physica status solidi (a)","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141648594","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}
In the present study, capacitance–voltage and triangular voltage sweep (TVS) measurements reveal mobile positively charged defects in both Ta2O5 and Nb2O5 layers deposited on thin SiO2 layers . These defects are not detected in the SiO2 layers before the deposition of high‐k oxides and their concentration depends significantly on the purity of the targets. The electrical properties of these defects are found to be similar to those of positively charged Na+ in SiO2. Vapor‐phase decomposition‐inductively coupled plasma‐mass spectrometry (VPD‐ICPMS) measurements show that Na is a dominant signal besides Ta and Nb after the deposition of Ta2O5 and Nb2O5, respectively. Considering these findings, the origin of the positively charged defects is discussed with an emphasis on their correlation with Na+.
在本研究中，电容-电压和三角电压扫描（TVS）测量揭示了沉积在二氧化硅薄层上的 Ta2O5 和 Nb2O5 层中的移动正电荷缺陷。在沉积高 K 氧化物之前，这些缺陷在二氧化硅层中是检测不到的，而且它们的浓度在很大程度上取决于靶材的纯度。研究发现，这些缺陷的电特性与二氧化硅中带正电的 Na+ 类似。气相分解-电感耦合等离子体质谱法（VPD-ICPMS）测量结果表明，在分别沉积 Ta2O5 和 Nb2O5 之后，Na 是除 Ta 和 Nb 之外的主要信号。考虑到这些发现，我们讨论了带正电缺陷的起源，重点是它们与 Na+ 的相关性。
{"title":"Positively Charged Defects in Ta2O5 and Nb2O5: Are They Correlated with Sodium Ions?","authors":"Vladimir Kolkovsky, Eberhard Kurth","doi":"10.1002/pssa.202400280","DOIUrl":"https://doi.org/10.1002/pssa.202400280","url":null,"abstract":"In the present study, capacitance–voltage and triangular voltage sweep (TVS) measurements reveal mobile positively charged defects in both Ta2O5 and Nb2O5 layers deposited on thin SiO2 layers . These defects are not detected in the SiO2 layers before the deposition of high‐k oxides and their concentration depends significantly on the purity of the targets. The electrical properties of these defects are found to be similar to those of positively charged Na+ in SiO2. Vapor‐phase decomposition‐inductively coupled plasma‐mass spectrometry (VPD‐ICPMS) measurements show that Na is a dominant signal besides Ta and Nb after the deposition of Ta2O5 and Nb2O5, respectively. Considering these findings, the origin of the positively charged defects is discussed with an emphasis on their correlation with Na+.","PeriodicalId":506741,"journal":{"name":"physica status solidi (a)","volume":"36 44","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141645532","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}
Oxygen atoms have been widely used in porous organic polymers, which has attracted much attention from researchers. Herein, porous organic polymer with high oxygen content is synthesized with oxygen‐rich monomer as construction unit and anhydrous aluminum chloride as catalyst; then phase‐change materials (PCMs) composites are prepared by self‐adsorption method. The pore properties of the oxygen‐rich porous organic polymer are characterized by nitrogen absorption and desorption method. The properties of the PCM composites are characterized by scanning electron microscopy, X‐ray diffraction, Fourier‐transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The results show that the oxygen‐rich porous organic polymer has high Brunauer–Emmett–Teller surface area (465 m2 g−1) and excellent thermal stability. The PCM composites possess high encapsulation rate (50.6 wt%) and latent heat (124.7 kJ g−1). After several thermal cycles, the thermal properties of all PCM composites are almost unchanged, and no leakage phenomenon is found. It can be seen that oxygen‐rich porous polymers have potential applications in PCM adsorption and thermal energy storage.
{"title":"Oxygen‐Rich Porous Organic Polymer for Thermal Energy Storage","authors":"Ping Huang, Xiaowei Jiang, Zheng Dai, Qin Zhang, Xiaosong Chen, Libo Ma, Weibin Gao, Xu Xiong","doi":"10.1002/pssa.202400362","DOIUrl":"https://doi.org/10.1002/pssa.202400362","url":null,"abstract":"Oxygen atoms have been widely used in porous organic polymers, which has attracted much attention from researchers. Herein, porous organic polymer with high oxygen content is synthesized with oxygen‐rich monomer as construction unit and anhydrous aluminum chloride as catalyst; then phase‐change materials (PCMs) composites are prepared by self‐adsorption method. The pore properties of the oxygen‐rich porous organic polymer are characterized by nitrogen absorption and desorption method. The properties of the PCM composites are characterized by scanning electron microscopy, X‐ray diffraction, Fourier‐transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The results show that the oxygen‐rich porous organic polymer has high Brunauer–Emmett–Teller surface area (465 m2 g−1) and excellent thermal stability. The PCM composites possess high encapsulation rate (50.6 wt%) and latent heat (124.7 kJ g−1). After several thermal cycles, the thermal properties of all PCM composites are almost unchanged, and no leakage phenomenon is found. It can be seen that oxygen‐rich porous polymers have potential applications in PCM adsorption and thermal energy storage.","PeriodicalId":506741,"journal":{"name":"physica status solidi (a)","volume":"45 17","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141645122","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}
Herein, nitrogen is doped into carbon quantum dots (N‐CQDs) using a hydrothermal method for the rapid detection of metolachlor in grain. The morphological features, elemental compositions, and optical properties of the N‐CQDs are then analyzed and investigated using transmission electron microscopy, X‐ray photoelectron spectroscopy, and fluorescence spectroscopy, respectively. Based on the principle of intramolecular charge transfer, a fluorescent probe is constructed for the rapid detection of metolachlor. Under optimal experimental conditions, the fluorescence intensity change values of the N‐CQDs and metolachlor concentration have a good linear relationship when the concentration of metolachlor is in the range of 0.0125−2.5 μg mL−1. An evaluation of the method shows that the method has good selectivity, reproducibility, and stability, with a limit of detection of 1.63 μg kg−1 and a limit of quantification of 3.92 μg kg−1. The spiked recoveries of six real samples are tested using a spiked recovery assay that yielded spiked recoveries in the range of 105.05−87.13%, and their relative standard deviations (n = 3) ranged from 4.62% to 0.61%, indicating that the method can be used for detection in actual samples with good precision and stability.
{"title":"Metolachlor Detection in Grain Using N‐Doped Carbon Quantum Dots and the Intramolecular Charge Transfer Effect","authors":"Jinchen Wang, Liyuan Zhang, Runzhong Yu","doi":"10.1002/pssa.202400172","DOIUrl":"https://doi.org/10.1002/pssa.202400172","url":null,"abstract":"\u0000Herein, nitrogen is doped into carbon quantum dots (N‐CQDs) using a hydrothermal method for the rapid detection of metolachlor in grain. The morphological features, elemental compositions, and optical properties of the N‐CQDs are then analyzed and investigated using transmission electron microscopy, X‐ray photoelectron spectroscopy, and fluorescence spectroscopy, respectively. Based on the principle of intramolecular charge transfer, a fluorescent probe is constructed for the rapid detection of metolachlor. Under optimal experimental conditions, the fluorescence intensity change values of the N‐CQDs and metolachlor concentration have a good linear relationship when the concentration of metolachlor is in the range of 0.0125−2.5 μg mL−1. An evaluation of the method shows that the method has good selectivity, reproducibility, and stability, with a limit of detection of 1.63 μg kg−1 and a limit of quantification of 3.92 μg kg−1. The spiked recoveries of six real samples are tested using a spiked recovery assay that yielded spiked recoveries in the range of 105.05−87.13%, and their relative standard deviations (n = 3) ranged from 4.62% to 0.61%, indicating that the method can be used for detection in actual samples with good precision and stability.","PeriodicalId":506741,"journal":{"name":"physica status solidi (a)","volume":"67 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141647559","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}
Sarita, Anchal, Priya, Shobha Ram Choudhary, M. S. Rulaniya, Arvind Kumar, S. N. Dolia, P. A. Alvi, B. L. Choudhary
The polycrystalline ferrite samples of NixCo1−xFe2O4 (x = 0.1, 0.3, 0.5, 0.7, and 0.9) are synthesized through the well‐known sol–gel method. The X‐ray diffraction (XRD) pattern confirms the cubic single‐phase spinel structure. Rietveld refinement indicates the absence of any other impurity phases in the samples. Additionally, XRD analysis reveals variations in lattice parameters corresponding to the doping. The Debye Scherer formula has been used to calculate the crystallite size of the samples, the crystallite size of the samples existing in the nanoregime. The results from field emission scanning electron microscopy confirm the morphological structure of the prepared samples. Additionally, the energy‐dispersive X‐ray spectra confirm the elemental composition and purity of the synthesized samples, validating the appropriateness of doping in the polycrystalline samples. The Raman spectra give the information about the vibrational modes in the sample. The Fourier transform infrared rays spectrum shows that the samples have a broad range of chemical interactions. The photoluminescence spectroscopy (PL) suggests strong luminescence in the visible range. PL spectroscopy provides that PL intensity decreases with increasing excitation wavelength due to nanosize of the particle.
{"title":"Studies of Structural, Optical, and Raman Analysis of Ni‐Substituted CoFe2O4","authors":"Sarita, Anchal, Priya, Shobha Ram Choudhary, M. S. Rulaniya, Arvind Kumar, S. N. Dolia, P. A. Alvi, B. L. Choudhary","doi":"10.1002/pssa.202400083","DOIUrl":"https://doi.org/10.1002/pssa.202400083","url":null,"abstract":"The polycrystalline ferrite samples of NixCo1−xFe2O4 (x = 0.1, 0.3, 0.5, 0.7, and 0.9) are synthesized through the well‐known sol–gel method. The X‐ray diffraction (XRD) pattern confirms the cubic single‐phase spinel structure. Rietveld refinement indicates the absence of any other impurity phases in the samples. Additionally, XRD analysis reveals variations in lattice parameters corresponding to the doping. The Debye Scherer formula has been used to calculate the crystallite size of the samples, the crystallite size of the samples existing in the nanoregime. The results from field emission scanning electron microscopy confirm the morphological structure of the prepared samples. Additionally, the energy‐dispersive X‐ray spectra confirm the elemental composition and purity of the synthesized samples, validating the appropriateness of doping in the polycrystalline samples. The Raman spectra give the information about the vibrational modes in the sample. The Fourier transform infrared rays spectrum shows that the samples have a broad range of chemical interactions. The photoluminescence spectroscopy (PL) suggests strong luminescence in the visible range. PL spectroscopy provides that PL intensity decreases with increasing excitation wavelength due to nanosize of the particle.","PeriodicalId":506741,"journal":{"name":"physica status solidi (a)","volume":"92 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141652804","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}
M. Ajmal Khan, Mitsuhiro Muta, Kohei Fujimoto, Javier Gonzalez Rojas, P. Fredes, Ernesto Gramsch, Yasushi Iwaisako, Hiroyuki Yaguchi, Hideki Hirayama
The increasing resistance of methicillin‐resistant Staphylococcusaureus to antibiotics is a major challenge faced by mankind in thehistory of medical science and according to United Nations, 700‐000 patients worldwide die every year from an infection with multidrug‐resistant organisms (MROs). Aluminum gallium nitride‐based 228 nm Far‐ultraviolet‐C (Far‐UVC) lightsources can be safely used as a germicidal application in both manned as wellas in unmanned environments against these MROs. Previously, the 228 nm Far‐UVC light‐emitting diode (LED) with emission power of 1 mW was reported by ourgroup, however, the value of external quantum efficiency (EQE) was not reportedusing conventional thick Ni (20 nm)/Au (100 nm) p‐electrode. Herein, animproved Far‐UVC LED on c‐Sapphire is attempted using a special technique in SR4000 type of metal‐organic chemical vapor deposition reactor to control the Al composition in n‐AlGaN buffer and across the 2 inch‐wafer. As a result, the light emission power of 1.8 mW and EQE of 0.32% in 228 nm Far‐UVC LED aresuccessfully achieved using very thin p‐electrode (Ni/Au). However, arelatively high junction temperature of ≈100°C around thejunction of Far‐UVC LED is observed. Finally, some simple heat‐sink modules forheat dissipation of Far‐UVC LED panel with light power of 30 mW are implemented.
{"title":"Estimation of Junction Temperature in Single 228 nm‐Band AlGaN Far‐Ultraviolet‐C Light‐Emitting Diode on c‐Sapphire Having 1.8 mW Power and 0.32% External Quantum Efficiency","authors":"M. Ajmal Khan, Mitsuhiro Muta, Kohei Fujimoto, Javier Gonzalez Rojas, P. Fredes, Ernesto Gramsch, Yasushi Iwaisako, Hiroyuki Yaguchi, Hideki Hirayama","doi":"10.1002/pssa.202400064","DOIUrl":"https://doi.org/10.1002/pssa.202400064","url":null,"abstract":"The increasing resistance of methicillin‐resistant Staphylococcusaureus to antibiotics is a major challenge faced by mankind in thehistory of medical science and according to United Nations, 700‐000 patients worldwide die every year from an infection with multidrug‐resistant organisms (MROs). Aluminum gallium nitride‐based 228 nm Far‐ultraviolet‐C (Far‐UVC) lightsources can be safely used as a germicidal application in both manned as wellas in unmanned environments against these MROs. Previously, the 228 nm Far‐UVC light‐emitting diode (LED) with emission power of 1 mW was reported by ourgroup, however, the value of external quantum efficiency (EQE) was not reportedusing conventional thick Ni (20 nm)/Au (100 nm) p‐electrode. Herein, animproved Far‐UVC LED on c‐Sapphire is attempted using a special technique in SR4000 type of metal‐organic chemical vapor deposition reactor to control the Al composition in n‐AlGaN buffer and across the 2 inch‐wafer. As a result, the light emission power of 1.8 mW and EQE of 0.32% in 228 nm Far‐UVC LED aresuccessfully achieved using very thin p‐electrode (Ni/Au). However, arelatively high junction temperature of ≈100°C around thejunction of Far‐UVC LED is observed. Finally, some simple heat‐sink modules forheat dissipation of Far‐UVC LED panel with light power of 30 mW are implemented.","PeriodicalId":506741,"journal":{"name":"physica status solidi (a)","volume":"18 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141107125","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}
N. Venkatesan, Gerardo Silva-Oelker, Wesley Turner, Jeong‐Sun Moon, Patrick Fay
Polarization grading in AlGaN/GaN‐based high‐electron‐mobility transistors (HEMTs) is a promising device design option that can improve linearity, speed, power, and noise performance for use in millimeter‐wave applications. This work investigates the potential of compositionally graded HEMT heterostructures to enhance device breakdown through lateral electric field engineering while maintaining a high device cutoff frequency (fT) due to reduced longitudinal optical (LO) phonon scattering. The impact of polarization grading on electric field profile is compared with conventional gate‐integrated mini‐field plates (mini‐FPs). It is also observed that polarization grading can augment the efficacy of gate‐connected FPs, further enhancing performance. Using physics‐based 2D device simulations, it is demonstrated that polarization engineering via polarization grading enhances breakdown (VBD) while preserving high fT, resulting in a Johnson's figure of merit (JFOM = fT × VBD), that is, ≈2.4× that of a conventional abrupt‐junction HEMT. This improvement represents a significant advancement over the ≈1.25× to ≈2× increase achieved with the use of mini‐FPs alone in HEMTs.
{"title":"Polarization‐Graded High‐Electron‐Mobility Transistors for Improved Johnson's Figure of Merit","authors":"N. Venkatesan, Gerardo Silva-Oelker, Wesley Turner, Jeong‐Sun Moon, Patrick Fay","doi":"10.1002/pssa.202300923","DOIUrl":"https://doi.org/10.1002/pssa.202300923","url":null,"abstract":"\u0000Polarization grading in AlGaN/GaN‐based high‐electron‐mobility transistors (HEMTs) is a promising device design option that can improve linearity, speed, power, and noise performance for use in millimeter‐wave applications. This work investigates the potential of compositionally graded HEMT heterostructures to enhance device breakdown through lateral electric field engineering while maintaining a high device cutoff frequency (fT) due to reduced longitudinal optical (LO) phonon scattering. The impact of polarization grading on electric field profile is compared with conventional gate‐integrated mini‐field plates (mini‐FPs). It is also observed that polarization grading can augment the efficacy of gate‐connected FPs, further enhancing performance. Using physics‐based 2D device simulations, it is demonstrated that polarization engineering via polarization grading enhances breakdown (VBD) while preserving high fT, resulting in a Johnson's figure of merit (JFOM = fT × VBD), that is, ≈2.4× that of a conventional abrupt‐junction HEMT. This improvement represents a significant advancement over the ≈1.25× to ≈2× increase achieved with the use of mini‐FPs alone in HEMTs.","PeriodicalId":506741,"journal":{"name":"physica status solidi (a)","volume":"37 23","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141113766","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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