Interfacial Permittivity Characterization of Heterogeneous Dielectric Bi-Layers

The increased demand for reliable and efficient energy storage capacitive devices has gained much attention in recent years. Developing a solid-state capacitor with substantially higher energy densities could transform power electronics and energy storage applications. In this work, it is demonstrated that dielectric/dielectric interfaces of certain common dielectrics (e.g., SiO
₂
, Si
₃
N
₄
, and Al
₂
O
₃
) potentially have an anomalous interfacial polarizability component that is tangential to the interfaces, which has not been extensively studied. To explore this component, extensive experimental measurements of the capacitances of interdigitated electrode (IDE) devices are used to excite heterogenous dielectric interfaces with electric fields that are parallel to the planes of those interfaces. These nanofabricated IDE devices enable the authors to estimate the volumetric average of this component of polarizability. By combining repeatable and highly precise fabrication methods with electromagnetic finite element method (FEM) simulations, the average relative permittivity within a 1-nm thick volume at the interfaces of Si
₃
N
₄
/SiO
₂
, Al
₂
O
₃
/SiO
₂
, and Al
₂
O
₃
/Si
₃
N
₄
are extracted to be
${k}_{\text {Si}_{{3}}\text {N}_{{4}}/\text {SiO}_{{2}}} = {1419}$
,
${k}_{\text {Al}_{{2}}\text {O}_{{3}}/\text {SiO}_{{2}}} = {2373}$
, and
${k}_{\text {Al}_{{2}}\text {O}_{{3}}/\text {Si}_{{3}}\text {N}_{{4}}} = {428}$
,
$\vphantom {^{\int }}$
respectively.