Surface Morphology, Phase Composition, and Local Electrical Properties of Fullerite Films Containing a Varied Atomic Fraction of Tin and Bismuth

Abstract

The surface morphology, elemental and phase compositions, and local electrical properties of fullerite films containing various atomic fractions of tin and bismuth have been studied using scanning probe microscopy, scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and Fourier transform IR spectroscopy. The films were grown on oxidized single-crystal silicon substrates by deposition from a combined atomic–molecular flow using resistive evaporation in vacuum. Their thickness was 1 μm. The as-grown films consisted of grains ranging in size from 30 to 200 nm. Their X-ray diffraction patterns showed reflections from C60 fullerite with a face-centered cubic lattice, which was in a stressed state due to the incorporation of dopant atoms, and reflections from pure tin and bismuth. Optical spectroscopy results indicated the formation of complexes of fullerenes with Sn and Bi atoms. According to electric force microscopy results, the tin- and bismuth-doped fullerite films have a considerably lower surface potential and a nonuniform surface capacitance gradient distribution.