Atomically Flat Silicon Oxide Monolayer Generated by Remote Plasma

Abstract

We demonstrate stable, atomically smooth monolayer oxidation of Si(111) using a remote plasma. Scanning tunneling microscopy (STM) confirms the atomically flat nature of the oxidized surface, while cross-sectional transmission electron microscopy (TEM) proves the monolayer to bilayer oxide thickness. Fourier transform infrared spectroscopy (FTIR) and atomic layer deposition (ALD) indicate oxygen is incorporated onto the silicon surface in the form of Si–O–Si and Si–OH bonds. The incorporation of Si–OH bonds is inferred by using TiCl4, a highly specific ALD precursor, for TiO2 ALD. This plasma technique provides precise control of the surface chemistry and yields abrupt yet stable SiO/Si interfaces. It enables production of atomically flat, ALD-active silicon surfaces that could serve as a well-defined platform for investigation of various surface chemistries via STM. Using this substrate, we present the first ever STM observations of ALD TiO2 on silicon oxide.