Reaction mechanism of ZrCl4 with Ge/Si(100)-(2×1): A density functional theory study of initial stage of ZrO2 atomic layer deposition on SiGe alloy surface

The reaction mechanism of ZrCl₄ adsorption and dissociation on Ge/Si(100)-(2×1) surface is investigated with density functional theory. The Si-Si, Si-Ge and Ge-Ge one-dimer cluster models are employed in the calculation to represent Ge/Si(100)-(2×1) surface with different Ge composition. The reaction of ZrCl₂ with hydroxylated Ge/Si(100)-(2×1) surface forms a bridged ZrCl₂ site, while on H-passivated surface ZrCl₃ site is formed. The reaction energy barrier of ZrCl₂ with H-passivated SiGe surface is much higher than ZrCl₄ with hydroxylated SiGe surface, which indicates that the reaction proceeds more slowly on H-passivated surface than on OH-terminated surface. The adsorbates and products on Ge-Ge dimer cluster model of Ge/Si(100)-(2×1) are most stable while structures on Si-Si dimer cluster model are least stable.