Impact of Native Defects in the High Dielectric Constant Oxide HfSiO_4 on MOS Device Performance

Native dejects in HfSiO4 are investigated by first principles calculations. Transition levels of native detects can be accurately described by employing the nonlocal HSE06 hybrid functional. This methodology overcomes the band gap problem in traditional functionals. By band alignments among the Si, GaAs and HfSiO4. we are able to determine the position of defect levels in Si and GaAs relative to the HfSiO4 band gap. We evaluate the. possibility of these defects acting as fixed charge. Native defects lead to the change of valence and conduction band offsets. Gate leakage current is evaluated by the band offset. In addition, we also investigate diffusions of native defects, and discuss how they affect the MOS device performance.

Sandwich-type composite multilayer films of strontium titanate and barium strontium titanate and their controllable dielectric properties

It is a challenge to reduce the dielectric loss and increase the tunability of pure barium strontium titanate(BST)films for microwave tunable application because these two properties change simultaneously.Herein,a novel composite of strontium titanate(ST)and potassium-doped BST(KBST)has been designed as ST/KBST/ST sandwich-type film with various ST and KBST layers.X-ray diffraction patterns show that the film exhibits cubic perovskite polycrystalline structure composed of BST and ST phase,mainly grow along(110)crystal plane with average grain size of less than 20 nm and decreasing BST phase/ST phase ratio with increasing film thickness.Scanning electron microscope shows that no interfacial layer can be observed,indicating that ST and KBST are fully compounded.Low dielectric loss and high tunability at-10-10 V and stable and excellent dielectric properties at 1 GHz are achieved,meeting the needs of microwave tunable application at high frequency.The surface structures are also studied by other analysis methods,and ST/MgBST/ST sandwich-type film is compared.

Photocrosslinkable Polynorbornene-based Block Copolymers with Enhanced Dielectric and Thermal Properties

Block copolymers poly（endo-N-3,5-bis（trifluoromethyl）biphenyl-norbornene-pyrrolidine）-block-poly（exo-N-（cinnamoyloxyethyl）-7-oxanorborn-5-ene-2,3-dicarboximide）（endo-PTNP-b-exo-PCONBI） and poly（exo-N-3,5-bis（trifluoromethyl）biphenyl-norbornene-pyrrolidine）-block-poly（exo-N-（cinnamoyloxyethyl）-7-oxanorborn-5-ene-2,3-dicarboximide）（exo-PTNP-b-exo-PCONBI） were synthesized by ring-opening metathesis polymerization. The endo- or exoPTNP served as the high dielectric functional chain, and exo-PCONBI acted as the crosslinking segment. The endo-PTNPb-exo-PCONBI, in which endo-PTNP has a high content of trans double bond and adopts isotactic configuration, shows a dielectric constant（？） of 15.5, whereas exo-PTNP-b-exo-PCONBI, in which exo-PTNP has 67% trans double bonds and atactic microstructure, displays relatively low ？ of 7.1. The cinnamate groups in exo-PCONBI were crosslinked to form three-dimensional network by cycloaddition reaction under UV irradiation. Exposed to UV-light for 10 min, the cinnamate group in polymer films has a crosslinking conversion of 36%, as determined by UV-Vis absorption measurements. By photocrosslinking, the polymer film has an increased ？ of 16.6, a dielectric loss of 0.03, an elevated glass-transition temperature of 137 ？C, and an enhanced decomposition temperature of 405 ？C, compared to those of polymer films without irradiation.

Dielectric tunable characteristics of compositional-gradient BaTi_(1-x)Sn_(x)O_(3)thin films

Compositional-gradient BaTi_(1-x)Sn_(x)O_(3)thin films on Pt(100)/Ti/SiO_(2)/Si substrates are fabricated with sol-gel using spin coating.All of the structures of the prepared thin films are of single-phase crystalline perovskite with a dense and crack-free surface mor-phology.BTS10/15/20 thin film exhibits enhanced temperature stability in its dielectric behavior.The temperature coefficient of capacitance TCC_(20-150)in the temperature range from 20°C to 150°C is−0.9×10^(−4)/°C and that of TCC20-(-95)in the temperature range from 20°C to−95°C is−3.8×10^(−4)/°C.Furthermore,the thin films show low leakage current density and dielectric loss.High and stable dielectric tunable performances are found in BTS10/15/20 thin films:the dielectric tunability of the thin films is around 20.1%under a bias voltage of 8 V at 1 MHz and the corresponding dielectric constant is in the range between 89 and 111,which is beneficial for impedance matching in circuits.Dielectric tunability can be obtained under a low tuning voltage,which helps ensure safety.The simulated resonant frequency of the compositional-gradient BTS thin films depends on the bias electric field,showing compositional-gradient BTS thin films could be used in electrically tunable components and devices.These prop-erties make compositional-gradient BTS thin films a promising candidate for dielectric tuning.

Side-Chain-Type Polyimide-Cu Complexes with Suppressed Activation Energy of Relaxation for Advanced High-Temperature Capacitor

The burgeoning growth of the new energy vehicles and aviation industry has escalated the need for energy storage capacitors capable of stable operation in harsh environments.The advent of metal-polyimide complexes has illuminated a novel approach for preparing tem perature-resistant capacitors.However,the general application of these metal-polyimide com plexes is impeded by the high dielectric loss and low breakdown strength,consequences of main-chain coordination and excessive metal ions content.Herein,our study proposes a novel polyimideCu complex material(POP-Cu)predicated on side-chain-type pyridine-Cu coordination,utilizing the structural backbone PMDA-ODA of mature commercial PI(Kapton)with reliable performance.Owing to the high degree of freedom afforded by the side chain with suppressed relaxation activation energy and the long-range electron delocalization formed by d-πcoordination,the dielectric constant of this material containing merely 2.7 mol%Cu increases from 3.25(POPI)to 5.58,while maintaining a remarkably low dielectric loss of 0.0066.Meanwhile,this material exhibits a substantial DC breakdown strength of 436.2 MV·m^(-1)and a high energy density of 5.42 J·cm^(-3),coupled with superior mechanical and thermal properties.Even at 150℃,it retains over 90%of its room-temperature energy density,demon strating notable dielectric stability under high temperatures.These attributes underscore its promising application for capacitors operating in harsh environments.