First-principles calculation of capacitance including interfacial effects

Abstract

An efficient computational method is proposed within a first-principles framework to calculate capacitances of metal-insulator-metal structures including interfacial effects. In this approach, we employ metal-insulator models under external electric fields to calculate dielectric responses near the interface region. Macroscopically averaged potentials allow for evaluating the capacitance and local dielectric constants of the corresponding metal-insulator-metal capacitor. We apply this method to calculate the capacitance of Au/MgO(100)/Au and Ni/ ZrO2 (110) /Ni with dielectric thicknesses of nanometers. While the Au/MgO interface is relatively free of interfacial effects, the computational results for Ni/ ZrO2 indicate the presence of interfacial regions with dielectric constants noticeably lower than that of the bulk. Microscopic origins are discussed. © 2008 American Institute of Physics.