Mechanism for Leakage Reduction by La Incorporation in a $\hbox {HfO}_{2}\hbox {/SiO}_{2}\hbox {/Si}$ Gate Stack

In this letter, we investigated a dominant mechanism for leakage reduction by the incorporation of La in a HfO₂/SiO₂ gate stack. We compared the experimental data for the leakage current for the La-doped HfO₂/SiO₂ gate stack and the calculation for tunnel current through the gate stack, assuming that the La-induced dipole increases the barrier height of HfO₂ for electrons from the substrate. The agreement between the experimental data and calculated values strongly suggests that the main cause for leakage reduction is the effective barrier height modulation induced by the interface dipole.