Surface Dielectric Properties Research Articles

Efficient gradient heating-up approach for rapid growth of high-quality amorphous ZrO2 dielectric films

High-k oxide dielectric films are indispensable for low-power-consumption oxide thin-film transistors (TFTs) applied in advanced and portable electronics. However, high-quality oxide dielectric films prepared by solution process typically require sophisticated processes and long thermal annealing time, severely limiting both the throughput manufacturing and cost-effectiveness. In this study, the influence of different heating-up methods on the surface morphology and dielectric properties was systematically investigated. Gradient heating-up method could not only substantially improve the surface morphology and quality of high-k ZrO2 films but also efficiently shorten the annealing time. The gradient heating-up process was further designed on the basis of thermal behavior of the xerogel-like precursor, which successfully realize the preparation of high-quality ZrO2 films with an annealing time of 5 min (i.e. the efficiency of thermal treatment increased by about 89%). The ZrO2 film presented excellent dielectric properties, including a low leakage current density of ∼10−8 A cm−2 (at 2 MV cm−1 ), a large areal capacitance of 169 nF cm−2 and a high dielectric constant of 20.41 (1 MHz). Furthermore, InSnZnO TFT based on the ZrO2 gate dielectrics shows an acceptable device performances, such as a high carrier mobility of 2.82 cm2 V−1 s, a high on/off current ratio of ∼105 and a low subthreshold swing of 0.19 V decade −1 at a low operation voltage of 5 V. This work provide a highly promising approach to fabricate high-quality solution-processed high-k oxide dielectric films employed for large-scale and low-power-consumption electronics.

Dynamic evolution investigation on the dielectric surface charging under electron irradiation with various energy distributions

Spacecrafts face various environmental risks in their working durations, thereinto, surface charging, which may result in abnormal operation of devices, is a typical detrimental effect and deserves to be deeply investigated, especially the charging process under various electron energy distributions. In this work, aiming to reveal the evolution process of surface charging in detail, we establish an approach for predicting surface potential under electron irradiation by considering the electron emission process. Mathematical relationships for the dependence of surface charging on the secondary electron yield properties of dielectric surfaces are established. The dynamic process of surface potential evolution is calculated for MgO and Al2O3 when the energy variation of incident electrons obeys uniform distribution, Gaussian distribution, and Maxwell distribution. By analyzing the dynamic equilibrium process of electron incidence/exit in the positively/negatively charged cases, the effect of electron energy on equilibrium surface potential and equilibrium time are quantitatively calculated. It is found that the surface potential will be a dozen volts when the surface is positively charged, surface charging of this magnitude does not have a noticeable effect, and the equilibrium time is short (several microseconds). However, the surface potential may reach very high levels (thousands of volts) leading to breakdowns when the dielectric surface is negatively charged, and its equilibrium time is 3 to 4 orders of magnitude higher than the positively charged case. Via calculating the surface potential under various incident distributions, we acquire the dynamic evolution process of surface potential evolution under different energy distributions, and find its consequence shows a similar tendency for the situation of constant energy irradiation. This work digs into the mechanism of surface charging under various irradiation situations, which makes sense for further works involving surface charging induced by electron irradiation with multiple energy distributions.

Lunar Impact Craters: New Perspectives From Full‐Polarimetric Analysis of Chandrayaan‐2 Dual‐Frequency SAR Data

AbstractWith the availability of the full‐polarimetry data from Chandrayaan‐2 Dual‐frequency Synthetic Aperture Radar (DFSAR) for the first time, the lunar impact craters are studied for comprehensive characterization, which was earlier limited due to hybrid‐polarimetry based observations. In conjunction with the conventional Circular Polarization Ratio (CPR), we explore the unique full‐polarimetric parameters such as Single‐bounce Eigenvalue Relative Difference and T‐Ratio which are sensitive to surface roughness and dielectric constant, respectively. We studied the polarimetric behavior of a total of 115 nos. of impact craters within a specific size range (∼1–25 km diameter) belonging to different categories viz. fresh, degraded, polar and non‐polar anomalous craters. Our results confirm that both kinds of non‐polar and polar anomalous craters overall hold centimeter‐decimeter scale surface roughness similar to the exterior of the fresh craters, which mainly leads to the anomalous nature of the craters. Our analysis indicates possible control of the crater degradation process on the change in the radar scattering behavior of the studied lunar craters. The crater degradation causes a reduction in the surface roughness and dielectric property (density) of the scatterers present in various craters leading to a change in the radar scattering behavior. Alongside, water ice, if at all present admixed into the regolith in the polar anomalous craters, is not in the form of dominant scatterers that can influence the radar signature. However, the occurrence of relatively higher CPR values in smooth low dielectric crater interiors supports the possibility of the presence of water ice in some of the studied polar anomalous craters belonging to Pre‐Imbrian to Imbrian lunar geological periods.

Effects of La-Doped HfO2 Films on Dielectric Properties by Sol-Gel Method

HfO2 and La-doped HfO2 with 20, 40, 50, and 60 mol% were deposited on silicon wafers by spin-coating technique. The crystallization process was annealed temperature at 600 °C. Then, characterization techniques of XRD, AFM, SEM, Full-field XRF imaging, and XAS were applied to reveal structural morphology, local structure, grain, distribution, etc. This study aims to investigate the effect of doping La into the HfO2 system on surface formation, microstructure, and dielectric properties. According to the results, RMS surface roughness, and grain size increased relative to La concentration levels. These films demonstrated homogeneous, low surface roughness, and crack-free. The XRD confirms the existence of the monoclinic phase in pure HfO2 and the mixture phase of the monoclinic and orthorhombic phases in La-doped HfO2 films. Increasing La concentration caused the structural transformation, the XAS of La L3 -edge indicating that lanthanum remained in the HfO2 system. Dielectric response based on interface-phase polarization was improved with La content from 0 mol% to 60 mol%. Compared with HfO2 film, the dielectric constant of La-doped HfO2 films was increased and dielectric loss was decreased.

Energy Storage Performance and Dielectric Properties of Surface Fluorinated BOPP Films

Various composite films with high energy storage performance and/or dielectric strength have been fabricated. However, due to some reasons, few of them have been used in practice, and BOPP film is still regarded as the state-of-the-art capacitor dielectric film. Previous work has indicated that direct fluorination can improve the dielectric strength of BOPP films. Herein, as a continuation of previous work, the energy storage performance and basic dielectric properties of the surface fluorinated BOPP film are investigated. The charge-discharge experimental results show that the surface fluorinated BOPP sample has the maximum energy storage or release density of 5.27 or 4.43 J/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , which is 59.8% or 44.6% higher than that of the virgin BOPP sample. The dielectric measurement results indicate that the surface fluorinated BOPP sample has slightly higher dielectric constant and dielectric loss than the virgin BOPP sample. The analyses of physicochemical characteristics reveal that the 0.75 μm thick fluorinated surface layer has a high degree of fluorination. The results of the calculation based on the three-layer dielectric model and the dielectric measurements further show that the fluorinated surface layer has high dielectric constant and loss factor, similar to non-perfluoropolymers. The enhancement of energy storage performance and dielectric strength is mainly attributed to the blocking of the fluorinated layer to electron injection from the cathode, due to a 60% reduction of the interfacial electric field and a decrease in free volume of the surface layer by the fluorination.

Calibrated microwave reflectance in low-temperature scanning tunneling microscopy.

We outline calibrated measurements of the microwave reflection coefficient from the tunnel junction of an ultra-high vacuum low temperature scanning tunneling microscope. The microwave circuit design is described in detail, including an interferometer for an enhanced signal-to-noise ratio and a demodulation scheme for lock-in detection. A quantitative, in situ procedure for impedance calibration based on the numerical three-error-term model is presented. Our procedure exploits the response of the microwave reflection signal due to the change of the tunneling conductance caused by sub-nm variation of the tunneling distance. Experimental calibration is achieved by a least-squares numerical fit of simultaneously measured conductance and microwave reflection retraction curves at finite conductance. Our method paves the way for nanoscale microscopy and spectroscopy of dielectric surface properties at GHz frequencies and cryogenic temperatures. This opens a promising pathway even for dielectric fingerprinting at the single molecule limit.

Variable Temperature Spectroscopic Ellipsometry as a Tool for Insight into the Optical Order in the P3HT:PC70BM and PC70BM Layers.

Two combined ellipsometric techniques-variable angle spectroscopic ellipsometry (VASE) and variable temperature spectroscopic ellipsometry (VTSE)-were used as tools to study the surface order and dielectric properties of thin films of a poly(3-hexylthiophene-2,5-diyl) (P3HT) mixture with a fullerene derivative (6,6-phenyl-C71-butyric acid methyl ester) (PC70BM). Under the influence of annealing, a layer of the ordered PC70BM phase was formed on the surface of the blend films. The dielectric function of the ordered PC70BM was determined for the first time and used in the ellipsometric modeling of the physical properties of the P3HT:PC70BM blend films, such as their dielectric function and thickness. The applied ellipsometric optical model of the polymer-fullerene blend treats the components of the blend as a mixture of optically ordered and disordered phases, using the effective medium approximation for this purpose. The results obtained using the constructed model showed that a layer of the ordered PC70BM phase was formed on the surface of the layer of the polymer and fullerene mixture. Namely, as a result of thermal annealing, the thickness of the layer of the ordered fullerene phase increased, while the thickness of the underlying material layer decreased.

Impact of tetra ethyl ortho-silicate and magnesium nitrate hexahydrate on dielectric characteristics of forsterite powder

Forsterite powder with different compositions of tetra ethyl ortho-silicate (TEOS) and magnesium nitrate hexahydrate (MNH) is synthesized using the sol-gel method. X-ray Diffraction (XRD) technique is used for structural analysis and phase identification for forsterite powder. Surface morphology and elemental composition of forsterite samples are also investigated using scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) techniques. In addition, an extensive study is performed to estimate the dielectric properties (dielectric constant, dielectric loss, alternating current conductivity and loss tangent) and their relationship with frequency at room temperature in the frequency range of 200 MHz–20 GHz using a vector network analyzer (VNA) assembly. Furthermore, the intense effect of TEOS and MNH on surface morphology and dielectric properties of forsterite powder is also discussed in detail by focusing on the application in medical implants.

Surface Groups and Dielectric Properties of Ti3C2Tx MXene Nanosheets after NH3·H2O Solvothermal Treatment under Different Temperatures

The rapid development of electronic technology has brought convenience and efficiency to the lives of modern people, while emphasizing the need for novel materials with designability and excellent dielectric properties at the same time. In this work, Ti3C2Tx MXene nanosheets (MNSs) underwent NH3·H2O solvothermal treatment at temperatures of 40 °C, 60 °C, 80 °C, 100 °C, 120 °C, 140 °C, 160 °C, and 180 °C. The changes in the surface groups and dielectric properties after the solvothermal treatment were studied. The solvothermal treatment increased the proportion of surface -OH groups, which was beneficial to the permittivity of the MNSs. However, as the treating temperature increased, the amount of -OH on the surface of the MNSs showed a reducing trend, according to XPS spectra. As the treating temperature rose from 40 °C to 80 °C, the real part of the permittivity of MNS sample showed a significant decrease, eventually remaining approximately stable in the 80 °C to 180 °C samples. The results of electromagnetic characterization were in line with the group proportion, as determined via the XPS O1s spectra, supporting the previous conclusion that the -OH group played an important role in the permittivity.

Terahertz nanospectroscopy of plasmon polaritons for the evaluation of doping in quantum devices

Abstract Terahertz (THz) waves are a highly sensitive probe of free carrier concentrations in semiconducting materials. However, most experiments operate in the far-field, which precludes the observation of nanoscale features that affect the material response. Here, we demonstrate the use of nanoscale THz plasmon polaritons as an indicator of surface quality in prototypical quantum devices properties. Using THz near-field hyperspectral measurements, we observe polaritonic features in doped silicon near a metal-semiconductor interface. The presence of the THz surface plasmon polariton indicates the existence of a thin film doped layer on the device. Using a multilayer extraction procedure utilising vector calibration, we quantitatively probe the doped surface layer and determine its thickness and complex permittivity. The recovered multilayer characteristics match the dielectric conditions necessary to support the THz surface plasmon polariton. Applying these findings to superconducting resonators, we show that etching of this doped layer leads to an increase of the quality factor as determined by cryogenic measurements. This study demonstrates that THz scattering-type scanning near-field optical microscopy (s-SNOM) is a promising diagnostic tool for characterization of surface dielectric properties of quantum devices.

Effects of Ion Irradiation on Modifying Surface Characteristics and Dielectric Properties of PVA Polymeric Materials

In this work, PVA polymeric sheets were irradiated utilizing a homemade ion beam cold cathode source for use in optoelectronics applications. The PVA films were exposed to hydrogen beams with fluence range 8 × 1017 to 24 × 1017 ions.cm−2. The structural and functional group characteristics of pure and treated PVA films were investigated using XRD and FTIR methods, which confirmed the success fabrication of the PVA films. In frequency of 102 to 5 × 106 Hz, the conductivity, electrical impedance, and dielectric modulus of untreated and treated samples were determined. The dielectric characteristics of PVA films exhibit a significant modification when subjected to a hydrogen beam. Additionally, after being exposed to 16 × 1017 ions, the dielectric constant ε′ improved from 0.0078 for un-irradiated PVA to 0.0395, and conductivity changed from 8.87 × 10−11 S cm−1 to 3.32 × 10−10 S cm−1. Moreover, the relaxation time for PVA is reduced from 28.4 × 10−5 s to 8.98 × 10−5 s for 8 × 1017 ions.cm−2 and to 3.5 × 10−5 s for 24 × 1017 ions.cm−2. The present study extends the potential use of the treated PVA films to a broader range of fields, including microelectronics.

Ordered/Disordered Structures of Water at Solid/Liquid Interfaces

Experiments and theory have revealed versatile possible phases for adsorbed and confined water on two-dimensional solid surfaces, which are closely related to the aspects of various phenomena in physics, chemistry, biology, and tribology. In this review, we summarize our recent works showing that the different water phases with disordered and ordered structures can greatly affect surface wetting behavior, dielectric properties, and frictions. This includes the ordered phase of water structure that induces an unexpected phenomenon, an “ordered water monolayer that does not completely wet water”, at T = 300 K on the model’s surface and some real, solid material, together with the anomalous low dielectric properties due to ordered water.

Porous PVDF mats with significantly enhanced dielectric properties and novel dipole arrangement for high-performance triboelectric nanogenerators

In the last decade, various materials and nanoscale modifications have been developed to enhance the performance of the triboelectric nanogenerators (TENGs). Electrospinning of polarizable materials, such as polyvinylidene fluoride (PVDF), has improvements in surface area and dielectric properties through the arrangement of dipoles’ orientation. However, the previously developed electrospun mats for TENG devices still suffer from (i) insufficient dielectric properties due to the presence of low-dielectric air, (ii) process complexity, and (iii) the need for nanoparticle additives. These issues are addressed in this study to develop porous electrospun PVDF mats with significantly enhanced dielectric properties and novel dipole arrangement. Smart multi-layer structures are introduced to overcome the dielectric characteristics of the degraded electrospun mats by the presence of the voids. The new material structure exhibited a significantly increased dielectric constant of 10, which was much higher than single-layer electrospun mats, and was even comparable to the pristine PVDF film without any porosity. Such a material with high dielectric constant and high area-to-volume ratio was utilized as a tribonegative layer in the TENG device, and the corresponding triboelectric performance was analyzed. An output voltage of over 130 V and a current of up to 12 μA were obtained, which were noticeably higher than those of pristine PVDF as well as those of single-layer electrospun mats. Such high performance remained unchanged even after 10,000 cycles. The developed electrospun PVDF mats in this study can therefore be used in the next generation of high-performance TENG devices.

Influence of the Fabric Topology on the Performance of a Textile-Based Triboelectric Nanogenerator for Self-Powered Monitoring

The fibrous surface of textiles offers a larger contact area and continuous contact with the skin, which makes them a prominent candidate for biomechanical energy harvesting using the triboelectric nanogenerator principle. Herein, a lightweight, comfortable, and robust wearable triboelectric nanogenerator (W-TENG) device is fabricated for its application in self-powered technologies. The TENG output is enhanced via a three-way process: using a textured yarn and modifying the textile material and its structural variation in fabric. The triboelectric performance is correlated to the surface morphology, roughness, and dielectric properties. The current research compares woven and knitted fabric triboelectric nanogenerators using nylon, cotton, polypropylene (PP), and polyester. The surface roughness of the different textile materials and the irregular surface morphology of woven and knitted structures are studied using a three-dimensional (3D) optical profilometer. It is observed that the convolutions on the PP and nylon yarn and the 3D configuration of knitted fabric impart higher roughness than their woven counterpart providing a larger contact area. The higher contact area between the nylon/PP pair of knitted fabric has shown 240.55, 64.96, and 460% increments in voltage, current, and power density, respectively, compared to the woven W-TENG. The knitted fabric-based TENG has additionally demonstrated improved breathability and suitability to generate electrical energy from various human motions.

Sisal cellulose paper based triboelectric nanogenerator with high performance for detection of chemical group substitution degree

Cellulose-derived materials have attracted extensive attention for applications in advanced electronics due to their abundance, low cost, light weight, and sustainability. Here, we report a paper-based triboelectric nanogenerator (TENG) which was made of sisal cellulose as the friction layer. The effects of the surface morphology, structure, and dielectric properties of sisal cellulose paper (SCP) on the output performance of SCP-TENG were discussed. It is found that the electrical output performance of the SCP-TENG can be improved and controlled by chemically modifying SCP with different polar groups of -NO2, -COCH3, -Cl, -Br, -CH3, -C2H5, which is closely related to the dielectric constant change of SCP. Among them, the dielectric constant of the nitrated SCP is the highest, and the electrical output performance of the corresponding SCP-TENG also exhibits the highest, with the short-circuit current, open-circuit voltage, charge and power density improving to 20.78 μA, 198 V, 103 nC/m2, 827.03 mW/m2, from 6.13 μA, 118 V, 53 nC/m2, and 256.97 mW/m2, respectively. Based on the linear relationship between the current intensity of the modified SCP-TENG and the degree of substitution of different groups, a chemical sensor for detecting the degree of group substitution was successfully fabricated. This work provides a new idea for broadening the application field of TENG.

Growth, optical, mechanical, dielectric properties of UV-nonlinear optical single-crystal of [(NH4) (Cd(NCS)3)]·C12H24O6

Single-crystal of ammonium (18-crown-6-ether) cadmium (II) tri-thiocyanate [(NH4)[Cd(NCS)3]; (ACCTC) has been grown with dimension 8 × 4 × 4 mm3 was grown from aqueous solution via slow evaporation solvent technique. The S-XRD was utilized to determine the grown single-crystal structure, where the crystalline compound of ACCTC adopts to be orthorhombic crystal system with the space group of Cmc21, and the calculated cell parameters are a = 14.7568 Å, b = 15.4378 Å and c = 10.6383 Å, volume V = 2423.54 Å3. The optical lower cut-off wavelength of the title compound of ACCTC is UV–vis-NIR spectra examined 239 nm. Moreover, the laser-induced surface damage threshold (LISDT), Vickers micro-hardness, and dielectric properties have been examined by the grown title compound of ACCTC. Overall, the experimental results suggest that a single-crystal of ACCTC can be the best nonlinear optical material and possess superior power density (Pd) compared to the KDP single-crystal.

Enhanced-performance droplet-triboelectric nanogenerators with composite polymer films and electrowetting-assisted charge injection

Droplet-Triboelectric nanogenerators (droplet-TENGs) are a promising renewable energy resource. Enhancing the dielectric surface properties is a primary requirement to increase the output performance of TENG device. In this study, droplet-TENGs are fabricated on indium tin oxide glass substrates with either (1) a pure amorphous fluoropolymer (AF) dielectric film; (2) a composite AF film doped with silk powder (AF/Silk); or (3) a composite AF film doped with polytetrafluoroethylene (PTFE) particles (AF/PTFEp). The energy-harvesting performance of the three devices is examined experimentally with and without the application of electrowetting-assisted charge injection (EWCI). For the AF and AF/Silk devices, the output current increases by approximately 12 times following the application of EWCI. Furthermore, the composite AF/Silk device also improves the current stability. The AF/PTFEp TENG increases the output current by approximately 5 times compared to that produced by the TENG with a pure dielectric layer. Moreover, the performance improvement increases to around 25 times following the application of EWCI. For all three devices, the output current increases with a reducing dielectric layer thickness. The output current also increases with an increasing concentration of the droplet solution. Overall, the results presented in this study provide a useful general understanding of the mechanisms underlying the operation of droplet-triboelectric nanogenerators. This research explores, for the first time, the effect of EWCI on composite material used for droplet-TENG and suggests possible strategies for enhancing the performance of such devices through an appropriate design of the dielectric layer and operating conditions.

Mechanistic insights into the ageing of EPDM micro/hybrid composites for high voltage insulation application

In this work, we explore the mechanistic insights into the aging of EPDM based micro/hybrid composites under following environment namely acid rain, cryogenic temperature, high temperature and UV irradiation. Physical properties and cross-link density changes were measured before and after aging which confirms the degradation of EPDM samples under high temperature and UV environment. Surface properties were also measured for the samples under various aging conditions. High-temperature aging resulted in an increase in contact angle whereas, UV has led to a major loss in contact angle for all the samples. Based on the chemical changes predicted by FTIR and NMR we propose a photo-oxidative degradation mechanism under UV irradiation and the influence of nano-micro filler at cryogenic and high temperature aging. Surface morphology and dielectric property of the samples were found to undergo major changes under high temperature and UV aging which directly influences the electrical insulation property of the composite. Finally, the study gives insights into the factor affecting the shelf life of the EPDM composites which are exposed mainly under the mentioned environment for its application in outdoor high voltage insulation applications and can help in overcoming the aging issues mainly faced by polymer composites.

Fracture Surface Analysis, Physical, Optical and Dielectric Properties of Bismuth-Based Glass Doped with Potassium Chromate

Bismuth glasses have been prepared from a commercial-grade chemical glass mixture doped with potassium chromate in different contents. They have been melted at 1250 °C for 4 h, quenched in a metal plate, and annealed at 500 °C for 20 min. The surface morphology of glass samples has been examined using scanning electron microscopy (SEM). The dielectric properties have been investigated. UV-Vis-NIR absorption has been analyzed. The results show the growth of microcrystal precipitated in the glass matrix, and colors of glass change from colorless to green and opaque with the increasing content of potassium chromate. The density of glass decreases with the increasing content of potassium chromate. The UV-Vis spectra show strong absorption of UV. The chromium-doped glasses not only absorb the UV but also the violet and/or blue lights which depend on the chromium contents.

Effects of Electrothermal Aging on Surface Morphology and Dielectric Properties of Poly(Ethylene Terephthalate) in Laminated Busbars

Poly(ethylene terephthalate) (PET) used as an insulating medium of laminated busbars is subjected to combined stresses of the dc electric field and elevated temperature. The coupling effect induces the electrothermal aging of PET, which weakens the busbar performance and thus threatens the long-term reliability of power electronics equipment. In this article, the dc electrothermal aging tests of a 50- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> PET film are carried out at varied aging temperatures of 60 °C, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$80~^{\circ }\text{C}$ </tex-math></inline-formula> , and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$100~^{\circ }\text{C}$ </tex-math></inline-formula> and a fixed electric field of 120 kV/mm. The surface becomes rougher with ongoing electrothermal aging. It is found that the surface roughness <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Sa</i> of samples increases from 95 to 2100 nm and the PET surface energy drops from 46.7 to 43.9 mN/m. Moreover, dc breakdown strength and volume resistivity decrease from 807 kV/mm and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6.75\times 10^{{16}}\,\, \Omega \cdot \text{m}$ </tex-math></inline-formula> to 556 kV/mm and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.97\times 10^{{16}}\,\,\Omega \cdot \text{m}$ </tex-math></inline-formula> , respectively. The aging performance of dc breakdown strength and volume resistivity is discussed based on trap characteristics, which are involved in the evolution of aggregation structure and molecular chain during electrothermal aging. The results of differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) reveal that in the initial aging stage, recrystallization leads to the increased deep trap depth and the crystalline region destruction, and the molecular chain scission results in the decreased deep trap depth in the late aging stage.