Atomic Layer Deposition of Al₂O₃ on H-Passivated GeSi: Initial Surface Reaction Pathways with H/GeSi(100)-2×1

The reaction mechanisms of Al(CH₃)₃ (TMA) adsorption on H-passivated GeSi(100)-2×1 surface are investigated with density functional theory. The Si-Ge and Ge-Ge one-dimer cluster models are employed to represent the GeSi(100)-2×1 surface with different Ge compositions. For a Si-Ge dimer of a H-passivated SiGe surface, TMA adsorption on both Si-H* and Ge-H* sites is considered. The activation barrier of TMA with the Si-H* site (1.2eV) is higher than that of TMA with the Ge-H* site (0.91eV), which indicates that the reaction proceeds more slowly on the Si-H* site than on the Ge-H* site. In addition, adsorption of TMA is more energetically favorable on the Ge-Ge dimer than on the Si-Ge dimer of H-passivated SiGe.