Atomic-layer surface reaction of SiH₄ on Ge(100)

The single atomic layer growth process of Si on a Ge(100) surface using SiH₄ has been investigated by ultraclean cold-wall low-pressure chemical vapor deposition (CVD). Self-limiting reaction of SiH₄ on the Ge surface was found at 260°C and the reaction step can be explained by Langmuir-type kinetics. The saturated surface concentration of Si atoms depends on the preheating conditions. A single atomic layer was found for preheating at 350°C in Ar and at 260°C in H2. However, in the case of preheating in H₂ at 350°C, the Si atom concentration hardly reached that of a single atomic layer. Reflection high-energy electron diffraction (RHEED) and Fourier-transform infrared reflection adsorption spectroscopy (FTIR/RAS) observations showed that a H-terminated dimer structure was formed on the Ge(100) surface after preheating in H₂ at 350°C. The density of the SiH₄ reaction sites on the H-terminated surface with the dimer structure is considered to be lower than that of the H-terminated unreconstructed surface and the H-free surface.