High Dielectric Constant Materials Research Articles

Topology Optimization Enabled High Performance and Easy‐to‐Fabricate Hybrid Photonic Crystals

AbstractPhotonic crystals (PtCs) can confine and guide electromagnetic waves within specific frequency ranges, forming the foundation for promising optical applications. To numerically design PtCs with broad bandgaps, materials with high dielectric constants are favored. However, fabricating these high dielectric constant materials into microstructures is extremely challenging and it suffers from limitation of low fabricating resolution. To address this problem, this paper proposes hybrid microstructures composed of an easy‐to‐fabricate core and a high dielectric constant coating layer, which leverages the strength of both materials. This paper establishes a topology optimization algorithm to generate these PtCs with maximized bandgaps. Numerical examples demonstrate the effectiveness of the proposed method in generating optimized unit cells for both transverse magnetic (TM) and transverse electric (TE) modes. The hybrid PtCs offer unprecedented opportunities for the fabrication of optical devices, encouraging further research on multimaterial optical systems and advanced optimization methods to explore photonic bandgap materials beyond those offered by the current photonic technology.

Reducing dielectric loss of ZnO ceramic by Nb2O5 additive: Investigation of microstructure and electrical properties

Research on high dielectric constant materials, such as zinc oxide (ZnO), has received significant attention due to their potential for modern microelectronics and high-density energy storage applications. However, the use of ZnO has been limited by its high dielectric loss. This study aims to reduce the dielectric loss of ZnO by investigating the effects of adding niobium oxide (Nb2O5) on its electrical properties. Four compositions with varying amounts of Nb2O5 (0, 0.5, 1, and 2wt%) were prepared. The disk samples were made via the pressing method and sintered at 1250 °C. In the sample with a high additive content, a secondary phase of ZnNb2O6 was identified. The addition of Nb2O5 resulted in substantial grain growth in the ZnO ceramic. The samples containing Nb2O5 showed reduced electrical conductivity and increased electrical resistance. The sample with 2 wt% Nb2O5 exhibited the lowest dielectric constant, dielectric loss, and electrical conductivity, along with the highest electrical resistance and ferromagnetic behavior. Particularly, this sample achieved an impressive dielectric constant of 52730 and a low dielectric loss of 0.32 at 1 kHz. This makes it a promising candidate for energy storage applications.

Crystal structure and dielectric properties of Ln2Ti2SiO9 (Ln = Pr and Nd)

Low loss and high dielectric constant materials are essentially desired for wide varieties of applications in electronics and communication technology. Herein the structure and dielectric properties of two titanosilicates, Ln2Ti2SiO9, for Ln = Pr3+ and Nd3+ are reported. Both materials are isostructural and have layered structure with layers of [LnTi2SiO9]3- and Ln3+ ions. Electrical properties of both have been analyzed by using the temperature and frequency dependent permittivity, loss, conductivity and modulus data. At room temperature, appreciable relative permittivity (35 for Nd2Ti2SiO9 and 22 for Pr2Ti2SiO9 over the frequency range of 100 Hz to 5 MHz) and low dielectric loss (like 0.007–0.03 at 100 Hz and 10−4-10−3 at 1 MHz). Analysis of dc-conductivity data of both compounds indicate that the conduction in both materials is due to the correlated barrier hopping (CBH) of polarons. The relaxation peak of modulus spectra indicates more non-Debye like relaxation in Pr2Ti2SiO9 than that in Nd2Ti2SiO9, and that is possibly due to increased correlation in the dynamics of hopping polarons in Pr2Ti2SiO9.

Synthesis, characterization, and dielectricity performance of bulk pristine Fe3+ and Li+ Co-substituted wurtzite ZnO

High dielectric constant materials are of technological importance as they lead to the miniaturization of electronic devices. The permittivity of a material determines the relative speed that an electrical signal can travel in that material. The dielectric properties of pure ZnO are developed due to the defects of zinc excess at the interstitial position and the lack of oxidation. Fe and Li co-doping in ZnO are envisaged here to develop high dielectric materials by converting the material into a p-type semiconductor without creating stoichiometric oxygen defects in the lattice and making it robust against the oxidizing atmosphere. The formation of single-phase Fe and Fe/Li co-doped wurtzite ZnO samples is confirmed by X-ray diffraction analysis. The Fe and Fe/Li doping depresses the concentration of the intrinsic donor and impedes the conduction mechanism resulting in the highest dielectric constant (ɛr′) equivalent to 612 and 90,000 are found for bulk pristine Zn0.9Fe0.1O and Zn0.8Li0.1Fe0.1O at 400oC with 1000 ​Hz applied frequency. Also with an increase in frequency, the dielectric constant and dielectric loss are found to decrease. This behavior is attributed to different hopping mechanisms and defects formed during synthesis.

Ring Resonator Measurement: Characterizing High Dielectric Constant Materials for the Fourth Industrial Revolution

This study introduces a ring resonator measurement technique targeting high dielectric constant materials. Operating within a frequency range of 0.1 GHz to 5 GHz, the resonator utilizes FR4 substrate and copper conductor. A significant departure from existing methods involves employing a silver-coated ring directly on the sample, mitigating Wheeler's gap issue induced by airgaps across material layers. Furthermore, the research reveals that as dielectric constants increase, microstrip line impedance drastically falls below 25 ohms, potentially leading to inaccurate loss tangent determinations. This paper focuses solely on HFSS simulations to demonstrate the method's feasibility. The proposed technique offers promising prospects for accurately characterizing high dielectric constant materials, thereby facilitating advancements in various applications, particularly within the Fourth Industrial Revolution framework- 5G and 6G technologies.

Quest for the porosity-regulated high dielectric and conductive performance of MOF by introducing nanoparticles: Performance evaluation at elevated temperatures

Metal-organic frameworks (MOFs) are among the novel materials that have drawn a lot of attention from the scientific and technological communities. There have been numerous reports of 3D MOFs in the scientific community, but due to distinct structural and electrical properties, scientists are particularly interested in zinc imidazole framework 8 (ZIF-8). Due to its characteristic low dielectric values, ZIF-8 is an excellent choice for low-dielectric applications. However, the incorporation of nanoparticles can increase the dielectric constant of ZIF-8. In this study, ZnO semiconducting nanoparticles are used as a filler of ZIF-8 due to their exceptionally high electron mobility, exciton binding energy, and wide band gap. We hypothesized that the incorporation of semiconducting nanoparticles (ZnO) inside ZIF-8 influences the porosity, pore size distributions, pore morphology, and interconnectivity of ZIF-8 which influences the polarization of pristine ZIF-8 and helps to increase the dielectric properties. ZnO has inherent ionic polarization which not only enhances the dielectric constant but also simultaneously decreases the dielectric loss which is essential for any dielectric materials. The dielectric constant was enhanced by 1.5 times after 5 wt% ZnO doping in ZIF-8 at room temperature and the enhancement was nearly five times at 150 °C. Simultaneously the dielectric loss decreases after ZnO doping compared to pristine ZIF-8. The tailoring of porosity, the number of pores, the presence of defects and oxygen vacancies are responsible for the modulated dielectric properties. The conductivity of ZIF-8 can also be tuned by the nanoparticles incorporation which indicates the larger production of drift electrons inside MOF in the presence of nanoparticles. The detailed morphological characteristics confirm the interaction between ZnO and ZIF-8. The result is a thorough understanding of the intrinsic and extrinsic electrical properties of ZIF-8 composites for future generations of technology. This work aimed to exploit possibilities of MOF towards high dielectric constant and low loss material by simple nanoparticle incorporation.

Optimizing the Crystallinity of a ZrO2 Thin Film Insulator for InGaZnO‐Based Metal–Insulator–Semiconductor Capacitors

AbstractThe utilization of a zirconium oxide (ZrO2) thin film as the insulator in a metal–insulator–semiconductor (MIS) capacitor to enhance the characteristics of thin‐film transistors is investigated. Although the high crystallinity of ZrO2 is favorable to achieving higher capacitance density in metal–insulator–metal capacitors with ZrO2 thin films, it decreases the capacitance with increasing applied bias in Mo/ZrO2/InGaZnO (IGZO)‐structured MIS capacitors. Through comprehensive physical, chemical, and electrical characterizations, this study investigated the mechanism underlying the decreasing capacitance with increasing the applied bias in the accumulation state of the Mo/ZrO2/IGZO‐structured MIS capacitor depending on the crystallinity of ZrO2. Furthermore, the investigation identifies the optimal crystal structure of ZrO2 thin films for IGZO‐based MIS capacitors, highlighting the importance of forming meso‐crystalline structures in high dielectric constant (k) materials to enhance the k value and mitigating the decrease in capacitance caused by the accumulated carrier loss through grain boundaries of ZrO2.

First-principles to explore the hydrogen storage properties of XPtH3 (X=Li, Na, K, Rb) perovskite type hydrides

Based on the first-principles, the hydrogen storage, mechanical, electronic, optical, thermodynamic and kinetic properties of XPtH3 (X = Li, Na, K, Rb) perovskites are investigated for the first time in this work. The lattice constants of the optimized LiPtH3, NaPtH3, KPtH3, and RbPtH3 are 3.54, 3.63, 3.80, and 3.90 Å, respectively. The Cauchy's pressure and the ratio of the bulk modulus to shear modulus (B/G) consistently prove that the XPtH3 hydrides all exhibit ductility. The investigation of electronic properties reveals that XPtH3 compounds exhibit metallic nature. According to Poisson's ratio and charge density distribution, the bonding type of XPtH3 hydrides is mainly ionic. The Bader partial net charges are also calculated to analyze the charge transfer in XPtH3 perovskites. The results of the optical properties of XPtH3 compounds reveal that they are high dielectric constant and high refractive index materials. It is found that the XPtH3 perovskites exhibit thermodynamic, mechanical, and dynamic stability. The gravimetric hydrogen storage capacities are 1.45, 1.35, 1.26, and 1.06 wt% for LiPtH3, NaPtH3, KPtH3, and RbPtH3, respectively. The hydrogen desorption temperatures of LiPtH3, NaPtH3, KPtH3 and RbPtH3 are 237.77, 225.39, 162.43, and 80.11 K, respectively. Our results suggest that LiPtH3 hydride is the most suitable material for hydrogen storage applications among the four compounds.

Novel halogenated cyclopentadienyl hafnium precursor for atomic layer deposition of high-performance HfO2 thin film.

High dielectric constant (high-k) materials play a crucial role in modern electronics, particularly in semiconductor applications such as transistor gate insulators and dielectrics in metal-insulator-metal (MIM) capacitors. However, achieving optimal crystallinity and suppressing interfacial layer formation during deposition processes remain key challenges. To address these challenges, this study introduces a novel approach using atomic layer deposition (ALD) with a new Hf precursor incorporating an iodo ligand. The synthesized precursor, IHf, demonstrates enhanced thermal stability and reactivity, leading to superior film properties. ALD deposition of HfO2 thin films using IHf yields excellent crystallinity and effectively inhibits interfacial layer formation, resulting in enhanced capacitance density and improved leakage current characteristics in MIM capacitors. Notably, IHf-deposited HfO2 films exhibit a significant reduction in leakage current, achieving an equivalent oxide thickness of 1.73 nm at a leakage current density of 7.02 × 10-8 A cm-2 @ +0.8 V. These findings highlight the potential of IHf as a promising precursor for high-performance electronic device fabrication, paving the way for advancements in semiconductor technology.

Ultra-low noise measurements of ionic transport within individual single-walled carbon nanotubes.

Despite 15 years of extensive investigation, the fabrication and study of nanofluidic devices that incorporate a single carbon nanotube (CNT) still represents a remarkable experimental challenge. In this study, we present the fabrication of nanofluidic devices that integrate an individual single-walled CNT (SWCNT), showcasing a notable reduction in noise by 1-3 orders of magnitude compared to conventional devices. This achievement was made possible by employing high dielectric constant materials for both the substrate and the CNT-covering layer. Furthermore, we provide a detailed account of the crucial factors contributing to the successful fabrication of SWCNT-based nanofluidic devices that are reliably leak-free, plug-free, and long-lived. Key considerations include the quality of the substrate-layer interface, the nanotube opening, and the effective removal of photoresist residues and trapped microbubbles. We demonstrate that these devices, characterized by a high signal-to-noise ratio, enable spectral noise analysis of ionic transport through an individual SWCNT, thus showing that SWCNTs obey Hooge's law in 1/f at low frequencies. Beyond advancing our fundamental understanding of ion transport in SWCNTs, these ultralow-noise measurements open avenues for leveraging SWCNTs in nanopore sensing applications for single-molecule detection, offering high sensitivity and identification capabilities.

Solving the issue of increasing forming voltage during device miniaturization in hafnium oxide-based resistive access memory using high-k sidewall material

An electrothermal coupling model of resistive random access memory (RRAM) was established based on the oxygen vacancy conduction mechanism. By resolving the partial differential equation for the coefficients, the variation process of the device resistance was simulated. In our studies, a device model was proposed which can accurately simulate the whole process of RRAM forming, reset, and set. Based on the established model, a new high dielectric constant (high-k) material (La2O3) is introduced as the sidewall material. The La2O3 sidewall material can concentrate the electric field and helps to speed up the formation of conductive filaments. The La2O3 sidewall can effectively reduce the forming voltage increase during the miniaturization process. Then, the influence of sidewall thermal conductivity on forming voltage is studied, and it is discovered that low thermal conductivity helps to reduce the model’s forming voltage and increase the temperature concentration. These findings serve as a foundation for more studies on the choice of sidewall materials.

7.86 kV GaN-on-GaN PN power diode with BaTiO3 for electrical field management

Devices based on gallium nitride (GaN) have great potential for high power switching applications due to the high breakdown field and high electron mobility. In this work, we present a vertical GaN-on-GaN PN power diode using high dielectric constant material, BaTiO3, for electrical field management and high breakdown voltages, in together with an optimized guard-ring and field plate design. Numerical simulation shows that with high-k dielectrics implemented, the peak electrical field at the PN interface is mitigated from 3.5 to 3.1 MV/cm under a reverse bias of −9.05 kV. The device design with BaTiO3 shows a breakdown voltage of 9.65 kV or about 600 V improvement. The fabricated diodes with a 57 μm thick drift layer demonstrate a breakdown voltage of 7.86 kV on a bulk GaN substrate. The device has an on-resistance of 2.8 mΩ cm2 and a Baliga figure of merit of 22 GW/cm2.

Autonomous hydrogel locomotion regulated by light and electric fields.

Autonomous robotic functions in materials beyond simple stimulus-response actuation require the development of functional soft matter that can complete well-organized tasks without step-by-step control. We report the design of photo- and electroactivated hydrogels that can capture and deliver cargo, avoid obstacles, and return without external, stepwise control. By incorporating two spiropyran monomers with different chemical substituents in the hydrogel, we created chemically random networks that enabled photoregulated charge reversal and autonomous behaviors under a constant electric field. In addition, using perturbations in the electric field induced by a dielectric inhomogeneity, the hydrogel could be attracted to high dielectric constant materials and autonomously bypasses the low dielectric constant materials under the guidance of the electric field vector. The photo- and electroactive hydrogels investigated here can autonomously perform tasks using constant external stimuli, an encouraging observation for the potential development of molecularly designed intelligent robotic materials.

The influence of dielectric materials on CO2 conversion performance of pulsed micro-gap cylindrical dielectric barrier discharge reactor

Abstract Dielectric barrier discharge (DBD) is a non-thermal plasma technology that shows promise for CO2 conversion. However, its efficiency depends on plasma processing parameters, reactor design, and reactor material. This study focused on the effect of dielectric barrier material on the CO2 conversion performance of a pulsed micro-gap DBD reactor. The results of this study show that the DBD reactor with alumina dielectric produced better CO2 conversion performance than the quartz reactor, with a maximum CO2 conversion of 50.17% compared to 21.91% with the quartz reactor. The DBD reactor with alumina dielectric produced a greater current peak and a higher number of micro-discharges than the quartz reactor, which suggests that the number of micro-discharges plays a dominant role in the CO2 conversion performance of the DBD reactor. The use of high dielectric constant material with high surface roughness could enhance the CO2 conversion performance of pulsed micro-gap DBD reactors.

Comparison of the Electrical Performance of AlN and HfO<sub>2 </sub>Passivation Layer in AlGaN/GaN HEMT

Different material thickness with medium and high dielectric constant can impact the performance and reliability of high electron mobility transistor device. With varying the thickness of the passivation layer, the effect of it towards the device performance is still unclear. Two different insulator layers with a medium dielectric and a high dielectric constant namely Aluminium Nitride and Hafnium Oxide are used as passivation layer in AlGaN/GaN HEMT. Both material performance was simulated via COMSOL software by varying the thickness and the drain current output were compared. The passivation layer thickness of 10nm at Vds=6 V and Vgs=5 V, HfO2 outperforms AlN with the output drain current of 39 mA compared to 35 mA respectively. It was observed that HfO2 can attain higher threshold voltage, Vth as compared to the AlN because of the influence of its material properties that shows a direct proportional relationship between Vth and dielectric constant. Using high dielectric constant material like HfO2, we observe the ON-voltage gradually decreases as the thickness of the passivation layer increased. Out of all the thickness simulated for HfO2 and AlN, 10nm produced the highest drain current output instead of layer thickness of 20nm.

Microwave band-pass filter in frequency reconfiguration with super substrate on cross-coupled line structure for LTE 2500, WiMAX and 5G based internet of things applications

In this paper, the conceptualization of frequency reconfigurable microwave band-pass filter with a super substrate in odd-even method, for Internet of Things (IoT) applications is explained. The prototype consists of band pass filter in cross-coupled line structure with a symmetric structure on dielectric substrate and rectangular slot joining the cross coupled lines. A two different types of super substrate are placed in the rectangular slot one after the other. In parallel to the process, another two different types of dielectric substrate (FR4 epoxy, Rogers RT/duroid 6010 LM (tm)) are placed one after the other above the proposed system producing a total of 6 combinations, each capitulate unique impedance parameters in the transmission poles and transmission zeros. The dimensional framework of the developed design structure have FR4 epoxy (εr = 4.4 and tan δ = 0.02) substrate with 1.6 mm thickness. In the first case, FR4 epoxy substrate is used to place in the rectangular slot in addition the same substrate is placed on top of the prototype. In the second case, slot is covered with Rogers RT/duroid 6010 LM (tm) (εr = 2.2 and tan δ = 0.0009) substrate and the same substrate is placed on the top. When the higher dielectric constant material is used as the addition of substrate the output range of the bandwidths are increased. In all the two cases, the proposed system demonstrates the ability to reconfigure the operating frequencies and bandwidth shifts from LTE 2500 (2496-2690 MHz), WiMAX (2500-2700 MHz, 3400-3600 MHz) to 5 G (3200- 3670 MHz).

Improved dielectric performance of polyvinylidene fluoride (PVDF) - Carbon dots composites

Polymer nanocomposites with high dielectric constant and low-loss tangent materials have been extensively used in devices. Polyvinylidene fluoride (PVDF)-carbon dot (C-dot) nanocomposites have been synthesized to investigate the effect of C-dot on AC conductivity and dielectric properties. The FTIR spectra of synthesized samples confirm the formation of composites. The broadening of the peak in XRD patterns with an increase in the C-dot concentration has been observed, indicating the interaction of PVDF with C-dot. Morphological studies were carried out using Scanning electron microscopy (SEM). Frequency-dependent conductivity and dielectric properties were studied in the frequency range of 10 Hz to 8 MHz. AC conductivity graphs were found to obey Jonscher's power law and show no contact loss behavior. Prepared samples show improved dielectric constant with an increase in C-dot filler concentrations. Moreover, all samples show tangent loss of less than 0.015 at 1 kHz frequency. These results demonstrate that composite possesses broad application prospects in device electronics.

Resolution enhancement using a multi-layered aluminum-based plasmonic device for chikungunya virus detection

Biomolecular variations can be accounted for by changes in the intrinsic properties of the surrounding medium, such as the refractive index. This work employs such an arrangement using a modified attenuated total internal reflection configuration for telecommunication wavelength (1550 nm). The phenomenon of surface plasmon resonance is initiated by Aluminum (Al) metal due to its low cost and better compatibility with CMOS devices. To achieve improved plasmonic response in terms of the sensor’s resolution, we have explored metal-dielectric-metal configuration under angle interrogation. Barium titanate and Molybdenum disulfide (MoS2) have been employed as the high dielectric constant material and the binding media respectively to enhance the sensing performance. After a series of optimizations, the proposed device configuration leads to a maximum Figure of Merit (FOM) of 540.9 RIU− 1, thus enhancing the resolution. The proposed plasmonic device can be used for chikungunya virus detection by considering different blood components in normal and infected stages. This Al-based multi-layered plasmonic device can serve many applications for resolution enhancement in the near-infrared region.

Pressure-induced novel ZrN4 semiconductor materials with high dielectric constants: a first-principles study.

In addition to Zr3N4 and ZrN2 compounds, zirconium nitrides with a rich family of phases always exhibit metal phases. By employing an evolutionary algorithm approach and first-principles calculations, we predicted seven novel semiconductor phases for the ZrN4 system at 0-150 GPa. Through calculating phonon dispersions, we identified four dynamically stable semiconductor structures under ambient pressure, namely, α-P1̄, β-P1̄, γ-P1̄, and β-P1 (with bandgaps of 1.03 eV, 1.10 eV, 2.33 eV, and 1.49 eV calculated using the HSE06 hybrid density functional, respectively). The calculated work functions and dielectric functions show that the four dynamically stable semiconductor structures are all high dielectric constant (high-k) materials, among which the β-P1̄ phase has the largest static dielectric constant (3.9 times that of SiO2). Furthermore, we explored band structures using the HSE06 functional and density of states (DOS) and the response of bandgaps to pressure using the PBE functional for the four new semiconductor configurations. The results show that the bandgap responses of the four structures exhibit significant differences when hydrostatic pressure is applied from 0 to 150 GPa.

High Dielectric Nonpolar Interfacial Layers Derived from Nanocellulose for Electrowetting Devices

AbstractA dielectric material is a particular type of insulator that does not conduct electricity but gets polarized when subjected to electricity, which is a crucial part of electronics such as cables, capacitors, displays, transformers, etc. Currently, synthesizing a nonpolar dielectric remains challenging. In this study, a method to make a high dielectric and nonpolar fluoropolymer and its nanocomposites based on cellulose nanocrystals (CNCs) by grafting it with nonpolar polymer 2,2,2‐trifluoroethyl methacrylate is reported. A high dielectric constant but nonpolar nanocellulose material is obtained for the first time. This material has an anisotropic arrangement of dipoles with a high polarizability effect, thereby displaying excellent dielectric properties (e.g., dielectric constant and loss: 8.59 and 0.017 at 10 kHz) and high stability (dielectric constant at 8.21 at 1 MHz). The dielectric material is miscible as an additive with other commercial fluoropolymer plastic, which demonstrates a high breakage voltage ranging from 4.6 to 9.2 kV/0.1 mm. When it is used as an interfacial layer in electrowetting display devices, it also demonstrated a low voltage driven and fast‐response effect. The excellent dielectric performances allow to develop more high‐performance dielectrics and electronics such as memories, sensors, actuators, wires, and film capacitors.