Hafnium oxide gate dielectrics on sulfur-passivated germanium

Sulfur passivation of Ge(100) is achieved using aqueous ammonium sulfide (NH4)(2)S(aq). The passivation layer is largely preserved after atomic layer deposition of the high-kappa dielectric material HfO2 when sufficiently low growth temperatures (e.g., 220 degrees C) are employed. Oxygen incorporation is moderate and results in an electrically passivating GeOS interface layer. The HfO2/GeOS/Ge gate stack exhibits lower fixed charge and interface state density than a more conventional HfO2/GeON/Ge gate stack fabricated via an ammonia gas treatment. (c) 2006 American Institute of Physics.