Pub Date : 2021-12-12DOI: 10.1109/NMDC50713.2021.9677542
C. Homes
The relative permittivity of a material is a scaling factor for capacitors and the devices based upon them; the larger the relative permittivity, the greater the degree of miniaturization, or potential for energy storage. Materials with a relative permittivity than that of silicon nitride (approximately 7) are referred to as high-dielectric constant materials. Values of about 100 are typical in titanium dioxide rutile. Values of about 10,000 are observed in barium titanate in the region of the ferroelectric transition, which while impressive, is not very useful due to the strong temperature dependence. The observation of a relative permittivity of over 100,000 in the calcium copper titanate material sparked considerable interest because it showed little temperature dependence between 100 and 600 K over most of the radio-frequency range. Further investigation revealed that this material appears to be naturally nanotextured and that the colossal permittivity was likely due to the surface and/or internal barrier layer capacitance effect, although the issue is not settled. Unfortunately, the dielectric losses in this class materials are relatively high. A new strategy to achieve high dielectric permittivity with low loss involves using localized lattice defect states through ambipolar co-doping; these intrinsic defect complexes give rise to strong dipoles that are responsible for a relative permittivity of 10,000 with exceptionally low dielectric losses over most of the radio frequency range and excellent thermal stability.
{"title":"Giant Polarization in Nanodielectrics: (Invited Paper)","authors":"C. Homes","doi":"10.1109/NMDC50713.2021.9677542","DOIUrl":"https://doi.org/10.1109/NMDC50713.2021.9677542","url":null,"abstract":"The relative permittivity of a material is a scaling factor for capacitors and the devices based upon them; the larger the relative permittivity, the greater the degree of miniaturization, or potential for energy storage. Materials with a relative permittivity than that of silicon nitride (approximately 7) are referred to as high-dielectric constant materials. Values of about 100 are typical in titanium dioxide rutile. Values of about 10,000 are observed in barium titanate in the region of the ferroelectric transition, which while impressive, is not very useful due to the strong temperature dependence. The observation of a relative permittivity of over 100,000 in the calcium copper titanate material sparked considerable interest because it showed little temperature dependence between 100 and 600 K over most of the radio-frequency range. Further investigation revealed that this material appears to be naturally nanotextured and that the colossal permittivity was likely due to the surface and/or internal barrier layer capacitance effect, although the issue is not settled. Unfortunately, the dielectric losses in this class materials are relatively high. A new strategy to achieve high dielectric permittivity with low loss involves using localized lattice defect states through ambipolar co-doping; these intrinsic defect complexes give rise to strong dipoles that are responsible for a relative permittivity of 10,000 with exceptionally low dielectric losses over most of the radio frequency range and excellent thermal stability.","PeriodicalId":6742,"journal":{"name":"2021 IEEE 16th Nanotechnology Materials and Devices Conference (NMDC)","volume":"9 4 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2021-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79676020","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}
Pub Date : 2021-12-12DOI: 10.1109/NMDC50713.2021.9677543
Xiao Xu, Zhehan Wang, Ke Zhan, Chenxu Bao, Zhengru Zhu, Bo Chang, Qichao Chen, Xu Jing, Li Tao
Two Dimensional (2D) materials and their combination with conductive polymers are emerging candidates for high-performance gas sensing with desirable mechanical flexibility. It is of great importance to understand the influence of applied strain to the sensing performance of such flexible sensors. In this work, we investigated the combination of graphene and polypyrrole (PPy) as flexible sensor devices and explored their ammonia sensing performance in-situ at bending. While having 1–5% responsivity when exposed to 5–35 ppm ammonia in flat condition, the response is raised generally under increasing strain denoted as the radius of curvature from 10 mm to 4 mm, with a peak value of 2.3% in 5 ppm NH3. Notably, the power consumption of our PPy-graphene sensor could be as low as $17 mumathrm{W}$. This work suggests PPy-graphene hybrid as energy-efficient and high-performance flexible sensor towards electronic skin for environmental monitoring.
{"title":"Energy-efficient Flexible Ammonia Sensors Enabled by Polypyrrole-Graphene","authors":"Xiao Xu, Zhehan Wang, Ke Zhan, Chenxu Bao, Zhengru Zhu, Bo Chang, Qichao Chen, Xu Jing, Li Tao","doi":"10.1109/NMDC50713.2021.9677543","DOIUrl":"https://doi.org/10.1109/NMDC50713.2021.9677543","url":null,"abstract":"Two Dimensional (2D) materials and their combination with conductive polymers are emerging candidates for high-performance gas sensing with desirable mechanical flexibility. It is of great importance to understand the influence of applied strain to the sensing performance of such flexible sensors. In this work, we investigated the combination of graphene and polypyrrole (PPy) as flexible sensor devices and explored their ammonia sensing performance in-situ at bending. While having 1–5% responsivity when exposed to 5–35 ppm ammonia in flat condition, the response is raised generally under increasing strain denoted as the radius of curvature from 10 mm to 4 mm, with a peak value of 2.3% in 5 ppm NH3. Notably, the power consumption of our PPy-graphene sensor could be as low as $17 mumathrm{W}$. This work suggests PPy-graphene hybrid as energy-efficient and high-performance flexible sensor towards electronic skin for environmental monitoring.","PeriodicalId":6742,"journal":{"name":"2021 IEEE 16th Nanotechnology Materials and Devices Conference (NMDC)","volume":"7 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2021-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81866200","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}
Pub Date : 2021-12-12DOI: 10.1109/nmdc50713.2021.9677487
Mohamed Delfag, R. Katoch, J. Jehn, Y. González, C. Schindler, A. Ruediger
{"title":"Sinter-free inkjet-printed PEDOT:PSS/WO3/ PEDOT:PSS flexible valency change memory","authors":"Mohamed Delfag, R. Katoch, J. Jehn, Y. González, C. Schindler, A. Ruediger","doi":"10.1109/nmdc50713.2021.9677487","DOIUrl":"https://doi.org/10.1109/nmdc50713.2021.9677487","url":null,"abstract":"","PeriodicalId":6742,"journal":{"name":"2021 IEEE 16th Nanotechnology Materials and Devices Conference (NMDC)","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75401253","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}
Pub Date : 2021-12-12DOI: 10.1109/nmdc50713.2021.9677536
C. Bennett, Samuel Liu, T. Xiao, Otitoaleke G. Akinola, Alexander J. Edwards, Wesley H. Brigner, Can Cui, Thomas Leonard, Mashid Alamdar, Naimul Hassan, R. Jacobs-Gedrim, J. Friedman, J. Incorvia, M. Marinella
{"title":"Quantized Domain-Wall Magnetic Tunnel Junction (DW-MTJ) Neural Networks Optimized for Rapid, Energy Efficient Edge Inference","authors":"C. Bennett, Samuel Liu, T. Xiao, Otitoaleke G. Akinola, Alexander J. Edwards, Wesley H. Brigner, Can Cui, Thomas Leonard, Mashid Alamdar, Naimul Hassan, R. Jacobs-Gedrim, J. Friedman, J. Incorvia, M. Marinella","doi":"10.1109/nmdc50713.2021.9677536","DOIUrl":"https://doi.org/10.1109/nmdc50713.2021.9677536","url":null,"abstract":"","PeriodicalId":6742,"journal":{"name":"2021 IEEE 16th Nanotechnology Materials and Devices Conference (NMDC)","volume":"41 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75820980","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}
Pub Date : 2021-12-12DOI: 10.1109/NMDC50713.2021.9677471
T. Tmenova, F. Valensi, A. Veklich, Y. Cressault, V. Boretskij
Pulsed underwater discharges are used for the synthesis of nanoparticles, through electrode tip vaporization and material condensation. The resulting colloid solution can have applications in biomedical (sterilization) or agriculture (plants fertilizing) field. The plasma formed from vaporized water and electrode material constitutes a key step in the process. This work is dedicated to studying plasma parameters as a function of current and used electrode material. Optical emission spectroscopic diagnostic is used to measure electronic temperature (based on copper or molybdenum lines) and density (based on $mathrm{H}_{alpha}$ and $mathrm{H}_{beta}$ lines). The setup allows spatially resolved study over the discharge cross-section. Results show that with molybdenum the core temperature is 30 to 90 % higher but the radial gradient is stronger when compared to copper. Electron density is also twice higher with molybdenum electrodes. High speed imaging confirms that with this metal the spark light intensity is much stronger and the formed cavitation bubble is larger. These results can be explained by the lower thermal conductivity of molybdenum electrodes, leading to a more energetic discharge.
脉冲水下放电通过电极尖端汽化和材料冷凝来合成纳米颗粒。所得胶体溶液可应用于生物医学(杀菌)或农业(植物施肥)领域。由蒸发的水和电极材料形成的等离子体是该过程的关键步骤。这项工作致力于研究等离子体参数作为电流和所用电极材料的函数。光学发射光谱诊断用于测量电子温度(基于铜或钼线)和密度(基于$mathrm{H}_{alpha}$和$mathrm{H}_{beta}$线)。该装置允许对放电截面进行空间分辨研究。结果表明:含钼合金芯温为30 ～ 90℃ % higher but the radial gradient is stronger when compared to copper. Electron density is also twice higher with molybdenum electrodes. High speed imaging confirms that with this metal the spark light intensity is much stronger and the formed cavitation bubble is larger. These results can be explained by the lower thermal conductivity of molybdenum electrodes, leading to a more energetic discharge.
{"title":"Spectroscopic Analysis of Pulsed Underwater Spark for Nanoparticles Synthesis Using Cu and Mo Electrodes","authors":"T. Tmenova, F. Valensi, A. Veklich, Y. Cressault, V. Boretskij","doi":"10.1109/NMDC50713.2021.9677471","DOIUrl":"https://doi.org/10.1109/NMDC50713.2021.9677471","url":null,"abstract":"Pulsed underwater discharges are used for the synthesis of nanoparticles, through electrode tip vaporization and material condensation. The resulting colloid solution can have applications in biomedical (sterilization) or agriculture (plants fertilizing) field. The plasma formed from vaporized water and electrode material constitutes a key step in the process. This work is dedicated to studying plasma parameters as a function of current and used electrode material. Optical emission spectroscopic diagnostic is used to measure electronic temperature (based on copper or molybdenum lines) and density (based on $mathrm{H}_{alpha}$ and $mathrm{H}_{beta}$ lines). The setup allows spatially resolved study over the discharge cross-section. Results show that with molybdenum the core temperature is 30 to 90 % higher but the radial gradient is stronger when compared to copper. Electron density is also twice higher with molybdenum electrodes. High speed imaging confirms that with this metal the spark light intensity is much stronger and the formed cavitation bubble is larger. These results can be explained by the lower thermal conductivity of molybdenum electrodes, leading to a more energetic discharge.","PeriodicalId":6742,"journal":{"name":"2021 IEEE 16th Nanotechnology Materials and Devices Conference (NMDC)","volume":"25 11 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2021-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79741276","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}
Pub Date : 2021-12-12DOI: 10.1109/nmdc50713.2021.9677476
G. R. Suwito, Weizheng Wang, N. Quitoriano
{"title":"Formation of Nano-Tree and Nano-Ring Structures from Au-Si-Ge Eutectic Solids","authors":"G. R. Suwito, Weizheng Wang, N. Quitoriano","doi":"10.1109/nmdc50713.2021.9677476","DOIUrl":"https://doi.org/10.1109/nmdc50713.2021.9677476","url":null,"abstract":"","PeriodicalId":6742,"journal":{"name":"2021 IEEE 16th Nanotechnology Materials and Devices Conference (NMDC)","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81500289","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}
Pub Date : 2021-12-12DOI: 10.1109/NMDC50713.2021.9677549
Olaiyan Alolaiyan, Abrar S. Alhazmi, Saeed Alghamdi, Faisal Alamri, Khalid Alhamdan, Awsaf Alsulami, Moh. R. Amer
2-Dimensional (2D) materials have been the subject of intensive research for electronic and photonic applications. Yet, the realization of a “good” ohmic contact with 2D materials is still a major hurdle that requires focused investigations. Metal deposition methods have proven to alter the electronic behavior of 2D materials, which can introduce defects and opens scattering paths for carriers. Here, we demonstrate new technique that can modulate contact resistance of the 2D material with the source and drain electrodes using MoS2 transistors. Exfoliated 2D Nanosheets are micro-aligned and deposited on prefabricated metal electrodes. Before any treatment, devices show poor electrical performance with high device resistance which is caused by weak contact between the 2D nanosheet and the metal electrodes. However, after applying a pulsed thermal annealing treatment with a short time interval, we notice a remarkable enhancement in $IV_{ds}$ and $IV_{gs}$ properties. For MoS2 transistors, we notice the maximum enhancement occurring after the first treatment. Our treatment can be a promising technique to create high performance electronics for device applications.
{"title":"Contact Modulation Using Pulsed Thermal Annealing in 2-Dimensional Semiconductors","authors":"Olaiyan Alolaiyan, Abrar S. Alhazmi, Saeed Alghamdi, Faisal Alamri, Khalid Alhamdan, Awsaf Alsulami, Moh. R. Amer","doi":"10.1109/NMDC50713.2021.9677549","DOIUrl":"https://doi.org/10.1109/NMDC50713.2021.9677549","url":null,"abstract":"2-Dimensional (2D) materials have been the subject of intensive research for electronic and photonic applications. Yet, the realization of a “good” ohmic contact with 2D materials is still a major hurdle that requires focused investigations. Metal deposition methods have proven to alter the electronic behavior of 2D materials, which can introduce defects and opens scattering paths for carriers. Here, we demonstrate new technique that can modulate contact resistance of the 2D material with the source and drain electrodes using MoS2 transistors. Exfoliated 2D Nanosheets are micro-aligned and deposited on prefabricated metal electrodes. Before any treatment, devices show poor electrical performance with high device resistance which is caused by weak contact between the 2D nanosheet and the metal electrodes. However, after applying a pulsed thermal annealing treatment with a short time interval, we notice a remarkable enhancement in $IV_{ds}$ and $IV_{gs}$ properties. For MoS2 transistors, we notice the maximum enhancement occurring after the first treatment. Our treatment can be a promising technique to create high performance electronics for device applications.","PeriodicalId":6742,"journal":{"name":"2021 IEEE 16th Nanotechnology Materials and Devices Conference (NMDC)","volume":"1 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2021-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88964598","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}
Pub Date : 2021-12-12DOI: 10.1109/NMDC50713.2021.9677527
Katarzyna E Hnida-Gut, M. Sousa, K. Moselund, H. Schmid
Electronic devices based on inexpensive Si technology by far dominate the market for data processing, imaging as well as sensing devices today and in the foreseeable future. Nevertheless, non-Si semiconductors are gaining significant momentum in specialized fields where it is motivated by performance metrics considerably surpassing that of Si. These include wide bandgap semiconductors (GaN) for power electronics and III-Vs (InSb, InGaAs, AlSb, etc.) for sensing and high-speed electronics. Therefore, a large economic potential could result if these two material platforms could seamlessly merge. However, technological difficulties challenge the integration of foreign materials directly on Si due to the crystal lattice, thermal and polarity mismatch leading to the large density of defects, detrimental to most applications. This work addresses this challenge demonstrating direct electrodeposition of indium antimonide on Si in defined geometries by an up-scalable and environmentally friendly aqueous solution process. We have evaluated several electrochemical deposition conditions with particular attention to stability and reproducibility of the process as well as an evaluation of the best electrode configuration. Building on these results, we show that prefabricated hollow template structures of micro- and sub-micron dimensions, each containing a local embedded electrode can be successfully filled with electrodeposited InSb resulting in well-defined device structures on Si. This combines the advantages of high-speed low-cost electrodeposition with the increased control achievable using templates.
目前和可预见的未来，基于廉价硅技术的电子设备在数据处理、成像和传感设备市场上占据主导地位。然而，非硅半导体在特殊领域获得了显著的动力，其性能指标大大超过了硅。其中包括用于电力电子的宽带隙半导体(GaN)和用于传感和高速电子的iii - v (InSb, InGaAs, AlSb等)。因此，如果这两种材料平台能够无缝融合，将产生巨大的经济潜力。然而，由于晶格、热和极性不匹配导致缺陷密度大，对大多数应用不利，因此直接在Si上集成外来材料面临技术困难。这项工作解决了这一挑战，通过一种可扩展的、环保的水溶液工艺，证明了锑化铟在硅上的直接电沉积具有确定的几何形状。我们评估了几种电化学沉积条件，特别注意该过程的稳定性和可重复性，以及对最佳电极配置的评估。在这些结果的基础上，我们展示了预制的微微米和亚微米尺寸的空心模板结构，每个模板都包含一个局部嵌入电极，可以成功地用电沉积的InSb填充，从而在Si上形成定义良好的器件结构。这结合了高速低成本电沉积的优点和使用模板可实现的更高控制。
{"title":"Direct Electrodeposition of InSb Devices on Silicon","authors":"Katarzyna E Hnida-Gut, M. Sousa, K. Moselund, H. Schmid","doi":"10.1109/NMDC50713.2021.9677527","DOIUrl":"https://doi.org/10.1109/NMDC50713.2021.9677527","url":null,"abstract":"Electronic devices based on inexpensive Si technology by far dominate the market for data processing, imaging as well as sensing devices today and in the foreseeable future. Nevertheless, non-Si semiconductors are gaining significant momentum in specialized fields where it is motivated by performance metrics considerably surpassing that of Si. These include wide bandgap semiconductors (GaN) for power electronics and III-Vs (InSb, InGaAs, AlSb, etc.) for sensing and high-speed electronics. Therefore, a large economic potential could result if these two material platforms could seamlessly merge. However, technological difficulties challenge the integration of foreign materials directly on Si due to the crystal lattice, thermal and polarity mismatch leading to the large density of defects, detrimental to most applications. This work addresses this challenge demonstrating direct electrodeposition of indium antimonide on Si in defined geometries by an up-scalable and environmentally friendly aqueous solution process. We have evaluated several electrochemical deposition conditions with particular attention to stability and reproducibility of the process as well as an evaluation of the best electrode configuration. Building on these results, we show that prefabricated hollow template structures of micro- and sub-micron dimensions, each containing a local embedded electrode can be successfully filled with electrodeposited InSb resulting in well-defined device structures on Si. This combines the advantages of high-speed low-cost electrodeposition with the increased control achievable using templates.","PeriodicalId":6742,"journal":{"name":"2021 IEEE 16th Nanotechnology Materials and Devices Conference (NMDC)","volume":"31 1","pages":"1-3"},"PeriodicalIF":0.0,"publicationDate":"2021-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89604976","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}
Pub Date : 2021-12-12DOI: 10.1109/NMDC50713.2021.9677546
M. Saidaminov
To reach their impressive power conversion efficiencies, perovskite solar cells have benefited from extensive empirical optimization. Major progress came from combinatorial optimization of perovskite compositions that now contain fully six or more components, e.g. Cs, MA, FA, Pb, I, Br, and others [1]. Unfortunately, the lack of understanding of the precise role of each component limits further progress in this now-exponentially-growing combinatorial space. Using ultrafast spatio-temporal imaging of carrier diffusion, we discovered that the carrier diffusivity is independent of composition in perovskite single crystals [2]. It is exclusively in polycrystalline thin films that different compositions play a crucial role in influencing carrier diffusivity and lifetime. Specifically, we found that in the stable cesium-formamidinium perovskite, perovskite films crystallize inhomogeneously: they produce grains whose cores have a lower bandgap, and whose shells have a higher bandgap. We then use this knowledge and find that the incorporation of a small amount of methylammonium homogenizes crystallization. This flattens the energetic landscape for carriers to move among grains. The proposed mechanism, through which the perovskite grain formation governs carrier transport, clarifies the widely-observed - but previously-unexplained - beneficial role of mixing.
{"title":"Competing Crystallization in Multi-ion Perovskites","authors":"M. Saidaminov","doi":"10.1109/NMDC50713.2021.9677546","DOIUrl":"https://doi.org/10.1109/NMDC50713.2021.9677546","url":null,"abstract":"To reach their impressive power conversion efficiencies, perovskite solar cells have benefited from extensive empirical optimization. Major progress came from combinatorial optimization of perovskite compositions that now contain fully six or more components, e.g. Cs, MA, FA, Pb, I, Br, and others [1]. Unfortunately, the lack of understanding of the precise role of each component limits further progress in this now-exponentially-growing combinatorial space. Using ultrafast spatio-temporal imaging of carrier diffusion, we discovered that the carrier diffusivity is independent of composition in perovskite single crystals [2]. It is exclusively in polycrystalline thin films that different compositions play a crucial role in influencing carrier diffusivity and lifetime. Specifically, we found that in the stable cesium-formamidinium perovskite, perovskite films crystallize inhomogeneously: they produce grains whose cores have a lower bandgap, and whose shells have a higher bandgap. We then use this knowledge and find that the incorporation of a small amount of methylammonium homogenizes crystallization. This flattens the energetic landscape for carriers to move among grains. The proposed mechanism, through which the perovskite grain formation governs carrier transport, clarifies the widely-observed - but previously-unexplained - beneficial role of mixing.","PeriodicalId":6742,"journal":{"name":"2021 IEEE 16th Nanotechnology Materials and Devices Conference (NMDC)","volume":"13 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2021-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88593783","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}
Pub Date : 2021-12-12DOI: 10.1109/NMDC50713.2021.9677517
Pawan Gaire, Veeru Jaiswal, S. Y. B. Sayeed, J. Volakis, M. Pulugurtha, S. Bhardwaj
Electric and magnetic properties of multiferroics can be conveniently tuned with applied electric and magnetic fields. Such tunability provides multiple design options for reconfigurable antennas and smart shielding applications and is thus of high interest. Dielectric tuning is commonly achieved with electric fields, which is more suitable with thin-films as they need lower voltages. For thick RF dielectrics that are used in antennas and Frequency Selective Surfaces (FSS), tuning requires 100s of Volts. To address this problem, we propose current-driven tuning of permittivity with integrated coils under the multiferroic. Tunable dielectric properties in nanostructured titanate paraelectrics are investigated through simulations by coupling them with magnetostrictive layers. In parallel, cosintered ferrite and paraelectric dielectrics are characterized for their tunability. The change in dielectric constant with magnetic fields is analyzed through multiphysics COMSOL simulations. Permittivity tuning is modeled with different coil currents. Applications in tunable FSS is demonstrated with such dielectric tuning.
{"title":"Tunable Multiferroics for Reconfigurable RF System Packages","authors":"Pawan Gaire, Veeru Jaiswal, S. Y. B. Sayeed, J. Volakis, M. Pulugurtha, S. Bhardwaj","doi":"10.1109/NMDC50713.2021.9677517","DOIUrl":"https://doi.org/10.1109/NMDC50713.2021.9677517","url":null,"abstract":"Electric and magnetic properties of multiferroics can be conveniently tuned with applied electric and magnetic fields. Such tunability provides multiple design options for reconfigurable antennas and smart shielding applications and is thus of high interest. Dielectric tuning is commonly achieved with electric fields, which is more suitable with thin-films as they need lower voltages. For thick RF dielectrics that are used in antennas and Frequency Selective Surfaces (FSS), tuning requires 100s of Volts. To address this problem, we propose current-driven tuning of permittivity with integrated coils under the multiferroic. Tunable dielectric properties in nanostructured titanate paraelectrics are investigated through simulations by coupling them with magnetostrictive layers. In parallel, cosintered ferrite and paraelectric dielectrics are characterized for their tunability. The change in dielectric constant with magnetic fields is analyzed through multiphysics COMSOL simulations. Permittivity tuning is modeled with different coil currents. Applications in tunable FSS is demonstrated with such dielectric tuning.","PeriodicalId":6742,"journal":{"name":"2021 IEEE 16th Nanotechnology Materials and Devices Conference (NMDC)","volume":"6 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2021-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86944743","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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