Dielectric materials

Dielectric materials are mainly used in the manufacture of capacitors in all areas of electrical engineering, microelectronics and telecommunications. Some dielectric materials also possess properties (ferroelectric, piezoelectric, pyroelectric, optical) with applications in sensors, actuators and nonlinear optics.

The first optimization criterion for capacitors is their capacitance C, which can be written as :

where ${ϵ}_0$ is the dielectric permittivity of vacuum, ${ϵ}_r$ the relative dielectric constant of the material used, S the surface area of the capacitor electrodes and e the thickness separating these two electrodes. Based on equation (1), we can see that the development of new capacitors involves either finding new materials to adapt ${ϵ}_r$ , or modifying the geometry of the capacitor S/e. This dual strategy is currently employed in the field of microelectronics when it comes to increasing C. If the S/e geometry is fixed, we seek to replace the current dielectric material (silica SiO ₂ , ${ϵ}_r=\mathrm{3,9}$ ) with an oxide of greater permittivity (for example, HfO ₂ , ${ϵ}_r=30$...