Polarization, piezoelectric constants, and elastic constants of ZnO, MgO, and CdO

We report first-principles density functional calculations of the polarizations, piezoelectric stress constants, and elastic constants for the II-VI oxides MgO, ZnO, and CdO in the wurtzite structure. Using our pseudopotential self-interaction corrected implementation of density functional theory, we obtain polarization values of -0.060, -0.022, and -0.10 C/m(2), and piezoelectric constants, e(33) (e(31)) of 1.64 (-0.58), 1.34 (-0.57), and 1.67 (-0.48) C/m(2) for structurally relaxed MgO (with its in-plane lattice parameter fixed to that calculated for ZnO), ZnO, and CdO, respectively. The large polarization gradients between the end-point compounds in the MgO-ZnO-CdO system augur well for the production of large internal fields in ZnO-based polarization field effect transistors.