Formation of atomically ordered and chemically selective Si-O-Ti monolayer on Si_0.5Ge_0.5(110) for a MIS structure via...

Si_0.5Ge_0.5(110) surfaces were passivated and functionalized using atomic H, hydrogen peroxide (H₂O₂), and either tetrakis(dimethylamino)titanium (TDMAT) or titanium tetrachloride (TiCl₄) and studied in situ with multiple spectroscopic techniques. To passivate the dangling bonds, atomic H and H₂O₂(g) were utilized and scanning tunneling spectroscopy (STS) demonstrated unpinning of the surface Fermi level. The H₂O₂(g) could also be used to functionalize the surface for metal atomic layer deposition. After subsequent TDMAT or TiCl₄ dosing followed by a post-deposition annealing, scanning tunneling microscopy demonstrated that a thermally stable and well-ordered monolayer of TiO_x was deposited on Si_0.5Ge_0.5(110), and X-ray photoelectron spectroscopy verified that the interfaces only contained Si-O-Ti bonds and a complete absence of GeO_x. STS measurements confirmed a TiO_x 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.