Density functional theory simulations and experimental measurements of a-HfO2/a-Si3N4/SiGe, a-HfO2/SiO0.8N0.8/SiGe and a-HfO2/a-SiO/SiGe interfaces

A comprehensive set of density functional theory (DFT) molecular dynamics (MD) simulations is presented for interfaces between a-HfO₂ high-K oxide and Si_0.5Ge_0.5(001) with several amorphous stoichiometric and substoichiometric SiOxNy interlayers (a-SiO_0.8N_0.8, a-SiO_0.4N_0.4, a-Si₃N₂, a-Si₃N₄ and a-SiO) to determine their electrical passivation properties. In general the sub-stoichiometric interlayers had superior electrical properties because they minimized Ge-O and Ge-N bond formation and had low internal bond strain. The stack with oxygen deficient a-SiO interlayer demonstrated superior electric properties because it avoided all dangling bond formation. Experimental studies confirmed that a sub-stiochiometric SiON layer decreases the defects density of HfO₂(001)/Si_0.5Ge_0.5(001) MOSCAPs.