Near-field infrared spectroscopy of SiOx nanowires

I.A. Milekhin, A. S. Kozhukhov, D. V. Sheglov, L. I. Fedina, A. G. Milekhin, A. V. Latyshev and D. R. T. Zahn

Applied Surface Science 584, 152583 (2022)
Scanning-probe-based patterning methods including local anodic oxidation have been widely used in nanotechnology to form various nanoelectronic device structures. However, so far spectroscopic investigations e.g. to determine the stoichiometry of oxide nanostructures with characteristic sizes below the diffraction limit do not exist. Using near-field infrared spectroscopy, we study the vibrational optical modes in SiOx nanowires with a height (width) of 2.1 nm (350 nm). The nanowires were produced by oxidation employing an atomic force microscope (AFM) on wide Si (1 1 1) terraces. The analysis of the spectroscopic data allows us to determine the composition of SiOx with a spatial resolution far below the diffraction limit. The composition × across SiOx nanowires is found to decrease from 1.6 in the center of the nanowire to 1.4 at its edges.