Characterization of termination layer of SiGe system through signatures of SiO and GeO species

Abstract

In this paper, we describe a novel method of employing the phenomenon of oxygen chemisorption for surface atom identification on a SiGe surface. On a clean Si(100), dosing 100 L O 2 (1 Langmuir = 1 s at 1 × 10 −6 Torr) at room temperature gives rise to peaks at 7 and 10.2 eV in ultraviolet photoelectron spectroscopy with He I excitation (HeI UPS) and O 1s is observed at 532.3 eV in X-ray photoelectron spectroscopy (XPS). Corresponding spectra for Ge(100) are a single peak at 5.2 eV in HeI UPS and O 1s at 531.3 eV. These signature spectra of SiO and GeO species have been effectively employed for unambiguous characterization of the termination layer of SiGe surfaces. Upon dosing at room temperature, on a sample prepared by depositing 5 Å Ge on Si(100) at 550°C, oxygen bonds with Ge atoms are forming GeO, exclusively. This indicates surface termination entirely by Ge atoms. Oxygen adsorption at room temperature, on a sample prepared by codeposition of Ge and Si (total 5 Å) onto Si(100) at 550°C, forms a mixed oxide suggesting a surface termination by both Ge and Si atoms.