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.

Dielectric nanocomposites with superb high-temperature capacitive performance based on high intrinsic dielectric constant polymer

Advancements in power electronics necessitate dielectric polymer films capable of operating at high temperatures and possessing high energy density.Although significant strides have been achieved by integrating inorganic fillers into high-temperature polymer matrices,the inherently low dielectric constants of these matrices have tempered the magnitude of success.In this work,we report an innovative nanocomposite based on sulfonylated polyimide(SPI),distinguished by the incorporation of sulfonyl groups within the SPI backbone and the inclusion of wide bandgap hafnium dioxide(HfO_(2))nanofillers.The nanocomposite has demonstrated notable enhancements in thermal stability,dielectric properties,and capacitive performance at elevated temperatures.Detailed simulations at both molecular and mesoscopic levels have elucidated the mechanisms behind these improvements,which could be attributed to confined segmental motion,an optimized electronic band structure,and a diminished incidence of dielectric breakdown ascribed to the presence of sulfonyl groups.Remarkably,the SPI-HfO_(2)nanocomposite demonstrates a high charge-discharge efficiency of 95.7%at an elevated temperature of 150℃and an applied electric field of 200 MV/m.Furthermore,it achieves a maximum discharged energy density of 2.71 J/cm^(3),signalling its substantial potential for energy storage applications under extreme conditions.

Synthesis of Large-Sized van der Waals Layered MoO_(3)Single Crystals with Improved Dielectric Performance

The applications of two-dimensional semiconductors strictly require the reliable integration of ultrathin high-κdielectric materials on the semiconductor surface to enable fine gate control and low power consumption.As layered oxide materials,MoO_(3)can be potentially used as a high-κtwo-dimensional material with a larger bandgap and high electron affinity.In this work,relying on the oxidization of molybdenum chlorides,we have synthesizedα-MoO_(3)single crystals,which can be easily exfoliated into flakes with thicknesses of a few nanometers and sizes of hundreds of micrometers and fine thermal stability.Based on measurement results of conventional metal/insulator/metal devices and graphene based dual-gate devices,the as-received MoO_(3)nanosheets exhibit improved dielectric performance,including high dielectric constants and competitive breakdown field strength.Our work demonstrates that MoO_(3)with improved crystalline quality is a promising candidate for dielectric materials with a large gate capacitance in future electronics based on two-dimensional materials.

Aluminum doping for optimization of ultrathin and high-k dielectric layer based on SrTiO3

An ultrathin SrTiO3 dielectric layer is optimized through Al doping to solve the problems existing in development of ultra-high-k oxide MOS capacitors.Through post-deposition annealing,Al doping induces changes in the electronic structure of SrTiO3,thereby effectively reducing leakage current to <10^-8 A/cm^2 at 0.5 MV/cm but maintains good capacitance values(ε> 80) of ultrathin SrTMO3 MOS capacitors.Strontium titanate(SrTiO3) is a high-k material but its bandgap is smaller than that of other oxide dielectrics(e.g.,SiO2,Al2 O3).Consequently,an ultrathin SrTiO3 film may have a high tunneling leakage current,which is not suitable for capacitor-based applications.To improve the performance of metal-oxide-semiconductor(MOS) capacitors using SrTiO3,an approach based on homogenous and uniform aluminum doping to SrTiO3 through co-sputtering is introduced.The bandgap of a pristine SrTiO3 film showed an increase of 0.5 eV after Al doping.Furthermore,Al doping decreased the leakage current of SrTiO3/Si-based MOS capacitors by more than five orders of magnitude(at the level of nanoampere per square centimeter).Importantly,a dielectric constant of 81.3 and equivalent oxide thickness less than 5 A were achieved in an 8-nm-thick Al-doped SrTiO3 film owing to changes in its crystal structure and conduction band edge electronic structure.Thus,the obtained data show the effectiveness of the proposed approach for solving the problems existing in the development of ultra-high-k oxide MOS capacitors.

Deep eutectic solvent inclusions for high-k composite dielectric elastomers

Recent advances in novel electroactive devices have placed new requirements on material development.High-performance dielectric elastomers with good mechanical stretchability and high dielectric constant are under high demand.However,the current strategy for fabricating these materials suffers from high cost or low thermal stability,which greatly hinders large-scale industrial production.Herein,we have successfully developed a novel strategy for improving the dielectric constant of polymeric elastomers via deep eutectic solvent inclusion by taking advantage of the low cost,convenient and environmentally benign synthesis process and high ionic conductivity from deep eutectic solvents.The as-prepared composite elastomers showed good stretchability and a greatly enhanced dielectric constant with a negligible increase in dielectric dissipation.Moreover,we have proven the universality of our strategy by using different types of deep eutectic solvents.It is believed that low-cost,easy-synthesis and environmentally friendly deep eutectic solvents including composite elastomers are highly suitable for large-scale industrial production and can greatly broaden the application fields of dielectric elastomers.