Electron spectroscopic identification of carbon species formed during diamond growth

Abstract

Carbon deposits formed during filament assisted diamond film growth were characterized with x-ray photoelectron spectroscopy (XPS) and electron energy-loss spectroscopy (EELS). The samples were transferred between the growth chamber and the ultrahigh vacuum analytical chamber without exposure to air. These results are presented with an emphasis on data analysis for carbon chemical state identification. By comparison of the C(1s) binding energies to a highly oriented pyrolytic graphite standard, we are able to distinguish pure carbon species, such as diamond and graphite, from compounds, such as SiC and CxHy. For substrates with Z≤30, the loss electrons from the C(1s) core level are free from overlap with the substrate core levels; therefore, EELS spectra can be obtained by x-ray excitation of the C(1s) level. These EELS data can then be used as a fingerprint for distinguishing between diamond, graphite, and carbides. For samples with mixed deposits of diamond and graphite, or carbide and diamond, curve fits of the EELS data can qualitatively determine which species are present.