MBE lanthanum-based high-k gate dielectrics as candidates for SiO2 gate oxide replacement

In this work, we investigate La-based complex oxides such as perovskite-like LaAlO3 and pyrochlore La2Hf2O7, deposited on rapid thermal SiO2 (RTO)/Si substrates using rf plasma source of atomic oxygen in an MBE chamber. The C–V curves measured in MIS capacitors were analyzed solving self-consistently the Poisson and Schrodinger equations to take into account quantum mechanical effects. From the dependence of the equivalent oxide thickness (EOT) as a function of physical thickness tph, the dielectric permittivity was estimated to be 14 and 18 for perovskite-like LaAlO3 (LAO) and pyrochlore La2Hf2O7 (LHO), respectively, which are lower than expected probably due to slight deviations from the stoichiometric compositions. Values of EOT∼1.1 nm and Jg∼2×10−3 A/cm2 at 1 V for the LAO, and EOT∼1.14 nm and Jg∼4×10−5 A/cm2 at 1 V for the LHO were obtained.