La 2 Hf 2 O 7 high-κ gate dielectric grown directly on Si(001) by molecular-beam epitaxy

Abstract

We show that at deposition temperature in the 750–770°C range, the La2Hf2O7 (LHO) compound can be grown crystalline on Si(001). The predominant orientation is (001)LHO∕∕(001)Si and [110]LHO∕∕[110]Si and results in ultimately clean interfaces, indicating a strong tendency for cube-on-cube epitaxy. The ordered pyrochlore and random fluorite phases coexist in the dielectric. Acceptable gate leakage current, negligible hysteresis and high dielectric permittivity κ∼23 were obtained from electrical characterization of metal–insulator–semiconductor capacitors. The quality of interfaces and the good electrical characteristics make crystalline LHO a promising high-κ candidate for the replacement of SiO2 in the gate of future aggressively scaled transistors.