High-k Polymer Research Articles

Silver/polymer nanocomposite as a high-k polymer matrix for dielectric composites with improved dielectric performance

A silver (Ag)-polymer nanocomposite has been developed by in-situ formation of metal nanoparticles within the polymer matrix and utilized as a high-dielectric constant (k) polymer matrix to enhance the dielectric properties of high-k composite materials. By using an in-situ photochemical reduction method, uniformly dispersed Ag nanoparticles of size of around 10 nm were generated in polymer matrices. Self-passivated aluminium (Al) particles were incorporated into this Ag-epoxy matrix and the dielectric properties of the as-prepared composite materials were investigated. The composites showed more than 50% increase in k values as compared with an Al/neat epoxy composite with the same filler loading of Al. The dielectric loss tangent of the Al/Ag-epoxy composites was below 0.1, which meets the requirement for embedded decoupling capacitors. These results suggest that the Ag-epoxy high-kpolymer matrix effectively enhances the dielectric constant while maintaining the low dielectric loss of the high-k composites. In addition, detailed dielectric property measurements revealed that the dielectric properties and their frequency dispersion as well as the breakdown behaviors of the Al/Ag-epoxy composites were related to the incorporation and concentration of Ag nanoparticles in the high-kpolymer matrix.

Parylene-C and High-k Polymer Bilayer Gate Dielectric for Low-Operating Voltage Organic Field-Effect Transistors

We propose a way to fabricate polymer insulators with a high gate capacitance for low-operating voltage organic field-effect transistors (OFETs). The insulator consists of spin-coated cyanoethylpullulan as a high-k polymer and chemical vapor deposited parylene-C as a covering layer. Parylene-C layer is insoluble in a common organic solvent, so the dielectric system can be fabricated on a layer of solution processable organic semiconductors such as poly(9,9-dioctylfluorene-co-bithiophene) (F8T2). The OFET shows a field-effect mobility of 3.4 × 10−3 cm2/Vs,a threshold voltage of − 1 V, and an on/off current ratio of 5.9 × 102. We successfully observed low-voltage operation in OFETs with this dielectric system.

Effect of the polymer matrices on the dielectric behavior of a percolative high-k polymer composite for embedded capacitor applications

High dielectric constant (high-k) polymer composites are of great interest for embedded capacitor applications. Previously, we demonstrated that epoxy—aluminum composites are promising for embedded capacitor applications, because they have a high dielectric constant and a low dielectric loss due to the core—shell structure of the self-passivated aluminum particles. In this work, to further understand the dielectric behavior of aluminum composites, lower-loss polymers such as silicone, polyimide, polynorbornene, and benzocyclobutene were explored as matrices for the aluminum composites. It is found that the polymer matrices can significantly change the dielectric properties of the aluminum composites. A polymer matrix with a lower dielectric constant generally results in a lower dielectric constant of its aluminum composites. In this regard, polymer—aluminum composites have a similar dielectric characteristic as polymer—ceramic composites. Thermomechanical properties of aluminum composites were characterized by a thermomechanical analyzer.

Synthesis and dielectric properties of novel high-K polymer composites containing in-situ formed silver nanoparticles for embedded capacitor applications

Dielectric properties of in-situ formed silver (Ag) incorporated carbon black (CB)/polymer composites were studied. In-situ formed Ag nanoparticles in the Ag/CB/epoxy composites increased the dielectric constant (K) value and decreased the dissipation factor (Df). The remarkably increased dielectric constant of the nanocomposite is due to the piling of charges at the extended interface of the interfacial polarization-based composites. The reduced dielectric loss might be due to the Coulomb blockade effect of the contained Ag nanoparticles, the well-known quantum effect of metal nanoparticles. The size, size distribution and loading level of metal nanoparticles in the nanocomposite were found to have significant influences on the dielectric properties of the nanocomposite system.

Low-loss percolative dielectric composite

In this letter, we report a modified percolative polymer composite that has a low dielectric loss (tanδ∼0.02@10KHz, comparable to that of the polymer matrix), a high dielectric constant (k>100@10KHz, about 30 times higher than that of the polymer matrix), and a low frequency dependence. This high-k polymer hybrid is filled with self-passivated micro- and nano-aluminum particles. The self-passivation of an aluminum particle results in dense nanoscale insulating Al2O3 shells outside of the metallic spheres, which allows the electrons in the metallic core to tunnel through it, and thereby the aluminum/polymer composites exhibit a high dielectric constant as a percolation system; on the other hand, the insulating oxide layer restricts the electron transfer between aluminum particles, thus leading to a very low loss of the composites.

High-mobility pentacene organic field-effect transistors with a high-dielectric-constant fluorinated polymer film gate dielectric

High-performance pentacene organic thin-film transistors with double layers of the terpolymer electret poly(vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene) and the polymer poly(vinyl cinnamate) as a gate dielectric are reported. The electret is a high-k dielectric polymer with a static dielectric constant of ε=14. The transistors show an intrinsic field-effect mobility in the range of μi=1cm2∕Vs and an on- to off-current ratio of about 105. High-k polymer gate dielectrics seem promising for organic nonvolatile memory and sensor field-effect transistors.

High-dielectric-constant all-polymer percolative composites

We report here an all-polymer high-dielectric (dielectric constant K>1000 at 1 kHz) percolative composite material, fabricated by a combination of conductive polyaniline particles (K>105) within a poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) terpolymer matrix (K>50). These high-K polymer hybrid materials also exhibit high electromechanical responses. For example, 1.5% strain, which is proportional to the square of the field applied, can be induced by a field of 9.5 MV/m, an eightfold reduction in field applied compared with that in a fluoroterpolymer matrix.

High-Dielectric-Constant All-Organic/Polymeric Composite Actuator Materials

ABSTRACTAmong various electroactive polymer (EAP) actuator materials developed recently, the class of EAPs whose responses are stimulated by external electrical fields (often known as the field type EAPs) is especially attractive due to their high strain level and elastic energy density. However, for most field type EAPs, dielectric constant is low, generally less than 10. Consequently, these polymers usually require high electric fields (>100 V/μm) to generate high elastic energy density which limits their applications. In this paper, we will investigate some avenues to significantly raise the dielectric constant and electromechanical response in field type polymeric materials. By exploiting an all-organic composite approach in which high-dielectric-constant organic particulates were blended with a polymer matrix, a polymeric-like material can reach a dielectric constant higher than 400, which results in a significant reduction of the applied field to generate high strain with high elastic energy density. An all-polymer high-dielectric-constant (K>1,000 @1 kHz) percolative composite material was fabricated by the combination of conductive polyaniline particles (K>105) within a fluoroterpolymer matrix (K>50). These high-K polymer hybrid materials also exhibit high electromechanical responses under low applied fields. In addition, a three-component all-organic composite was designed and prepared to improve the dielectric constant and the electromechanical response, as well as the stability of the composites, in which a high-dielectric-constant organic dielectric phase and an organic conductive phase were embedded into the soft dielectric elastomer matrix.

Dielectric Properties of Multi-Layer High-K Polymer Composite Films

ABSTRACTThe electrical properties of thin polymer films are key parameters in the design of both smaller and faster circuit devices in the microelectronics industry. In this study, we made a three-layer film structure, ABA', to investigate the dielectric interaction between two high-K dielectric polymer thin films, A and A', as a function of the thickness of the middle B layer. The Cole-Cole plot showed clear changes with the thickness of the middle B layer. The total capacitances were evaluated with a simple serial three capacitances model. This ABA' structure is thought to be very useful for studying mechanical and thermal properties of thin polymer film system.