Scanning Photoemission Spectromicroscopic Study of 4-nm Ultrathin SiO_3.4 Protrusions Probe-Induced on the Native SiO₂ Layer

Abstract Atomic force microscopy probe-induced large-area ultrathin SiO_x (x ≡ O/Si content ratio and x > 2) protrusions only a few nanometers high on a SiO₂ layer were characterized by scanning photoemission microscopy (SPEM) and X-ray photoemission spectroscopy (XPS). SPEM images of the large-area ultrathin SiO_x protrusions directly showed the surface chemical distribution and chemical state specifications. The peak intensity ratios of the XPS spectra of the large-area ultrathin SiO_x protrusions provided the elemental quantification of the Si 2p core levels and Si oxidation states (such as the Si⁴⁺, Si³⁺, Si²⁺, and Si¹⁺ species). The O/Si content ratio (x) was evidently determined by the height of the large-area ultrathin SiO_x protrusions.