Atomic imaging and modeling of H2O2(g) surface passivation, functionalization, and atomic layer deposition nucleation on the Ge(100) surface.

Passivation, functionalization, and atomic layer deposition nucleation via H2O2(g) and trimethylaluminum (TMA) dosing was studied on the clean Ge(100) surface at the atomic level using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). Chemical analysis of the surface was performed using x-ray photoelectron spectroscopy, while the bonding of the precursors to the substrate was modeled with density functional theory (DFT). At room temperature, a saturation dose of H2O2(g) produces a monolayer of a mixture of -OH or -O species bonded to the surface. STS confirms that H2O2(g) dosing eliminates half-filled dangling bonds on the clean Ge(100) surface. Saturation of the H2O2(g) dosed Ge(100) surface with TMA followed by a 200 °C anneal produces an ordered monolayer of thermally stable Ge-O-Al bonds. DFT models and STM simulations provide a consistent model of the bonding configuration of the H2O2(g) and TMA dosed surfaces. STS verifies the TMA/H2O2/Ge surface has an unpinned Fermi level with no states in the bandgap demonstrating the ability of a Ge-O-Al monolayer to serve as an ideal template for further high-k deposition.