Formation of atomically ordered and chemically selective Si-O-Ti monolayer on SiGe(110) for a MIS structure via HO(g) functionalization.

SiGe(110) surfaces were passivated and functionalized using atomic H, hydrogen peroxide (HO), and either tetrakis(dimethylamino)titanium (TDMAT) or titanium tetrachloride (TiCl) and studied in situ with multiple spectroscopic techniques. To passivate the dangling bonds, atomic H and HO(g) were utilized and scanning tunneling spectroscopy (STS) demonstrated unpinning of the surface Fermi level. The HO(g) could also be used to functionalize the surface for metal atomic layer deposition. After subsequent TDMAT or TiCl dosing followed by a post-deposition annealing, scanning tunneling microscopy demonstrated that a thermally stable and well-ordered monolayer of TiO was deposited on SiGe(110), and X-ray photoelectron spectroscopy verified that the interfaces only contained Si-O-Ti bonds and a complete absence of GeO. STS measurements confirmed a TiO monolayer without mid-gap and conduction band edge states, which should be an ideal ultrathin insulating layer in a metal-insulator-semiconductor structure. Regardless of the Ti precursors, the final Ti density and electronic structure were identical since the Ti bonding is limited by the high coordination of Ti to O.