Effects of electrostatic force on piezoelectric materials under high electric field: Impact on GaN-based nanoscale structures

摘要

The determination of the electromechanical properties of materials for aparallel-plate capacitor structure is affected by the electrostatic forcebetween their electrodes. The corrections induced by thiselectric-field-induced stress are usually assumed to be linked to the quadraticdependence of the strain on the electric field (electrostriction). Here we showby calculations based on thermodynamic grounds for this simple structure thatthe effect of the electrostatic force on piezoelectric materials can lead toboth quadratic and linear corrections through the combination of thepiezoelectric coupling and spontaneous polarization. The case of GaN-basedcapacitor nanoscale structures is presented taking into account the boundaryconditions imposed as well as the effect of geometry. The results in thisexample point to corrections in the piezoelectric and electrostrictivecoefficients higher than 0.3 pmV-1 and 2.6x10-22 m2V-2, respectively.