Crystalline Zro2-Gated Ge Metal-Oxide-Semiconductor Capacitors Fabricated On Si Substrate With Y2o3 As Passivation Layer

By adopting an amorphous Y2O3 passivation layer, which provides a wide band gap and well passivates Ge surface without the presence of GeOx, a high-permittivity (kappa) crystalline ZrO2/Y2O3 stack was explored as the gate dielectric for Ge metal-oxide-semiconductor (MOS) devices on Si substrate. The crystalline ZrO2 is a Ge stabilized tetragonal/cubic dielectric with the kappa value of 36.1 and was formed by depositing a ZrO2/Ge/ZrO2 laminate and a subsequent 500 degrees C annealing. The high-kappa crystalline ZrO2/Y2O3 gate stack shows promising electrical characteristics in terms of low interface trap density of 5.8 x 10(11) cm(-2) eV(-1), negligible hysteresis, and leakage current of 5.6 x 10(-4) A/cm(2) at gate bias of flatband voltage (V-FB) 1 V for equivalent oxide thickness of 1.13 nm. This gate stack not only demonstrates the eligibility for advanced Ge MOS devices but introduces a more reliable process to form a high-kappa crystalline gate dielectric. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3590923]