As ideal candidates for next-generation energy storage devices,nanocapacitors are predicted to exhibit very high capacitance according to classical theory.However,the actual capacitance of nanocapacitors is dramatical...As ideal candidates for next-generation energy storage devices,nanocapacitors are predicted to exhibit very high capacitance according to classical theory.However,the actual capacitance of nanocapacitors is dramatically lower than expected.This is attributed to the so-called‘dead-layer’effect associated with the flexoelectricity of dielectric films and the incomplete screening of metal electrodes.In this paper,a way to mitigate this negative effect is demonstrated by using graded dielectric films instead of homogeneous films.The enhancements due to grading dielectric films were obtained by using perturbation theory to solve the governing equations with boundary conditions in Mindlin’s model of parallel-plate capacitors.We have shown that by grading both the relative permittivity and the elastic constant,we can obtain enhancement of almost 27%in capacitance for the 2.7 nm SrTiO_(3) dielectric film.In addition,the impact of various dielectric film properties on the overall capacitance was investigated.展开更多
文摘As ideal candidates for next-generation energy storage devices,nanocapacitors are predicted to exhibit very high capacitance according to classical theory.However,the actual capacitance of nanocapacitors is dramatically lower than expected.This is attributed to the so-called‘dead-layer’effect associated with the flexoelectricity of dielectric films and the incomplete screening of metal electrodes.In this paper,a way to mitigate this negative effect is demonstrated by using graded dielectric films instead of homogeneous films.The enhancements due to grading dielectric films were obtained by using perturbation theory to solve the governing equations with boundary conditions in Mindlin’s model of parallel-plate capacitors.We have shown that by grading both the relative permittivity and the elastic constant,we can obtain enhancement of almost 27%in capacitance for the 2.7 nm SrTiO_(3) dielectric film.In addition,the impact of various dielectric film properties on the overall capacitance was investigated.
