Diamond nucleation and growth at the early stages on Si(100) monitored by electron spectroscopies

Abstract

Diamond growth on Si(100) is studied by scanning Auger microscopy (SAM), Auger electron spectroscopy (AES), electron loss spectroscopy (ELS) and X-ray photoelectron spectroscopy (XPS) focussing on the early stages of nucleation and growth. The low nucleation density allows us to monitor the evolution of both the substrate and the deposit intensities during the deposition process. Using the structural and chemical imaging probe provided by scanning Auger electron microscopy, we localize areas formed by carbon, only of diamond-type, and featureless areas with C, Si and O. The carbon nature on these last domains is initially a complex mixture of amorphous carbon, carbide and diamond. The amorphous deposit rapidly disappears (30 min), but the occurrence of surface carbide is still detected even after 120 min of growth. The surface carbon content, recorded both by AES focussed on the featureless domains and by XPS, initially drops. This is interpreted by the formation of silicon carbide embedding or removing the amorphous carbon layer. We identify three different sites of nucleation, which are (i) diamond seeds left by the substrate pretreatment; (ii) amorphous carbon at the very beginning of the nucleation process and (iii) silicon carbide. Then the diamond growth and the carbide formation are competitive processes, limited by (i) the reactive content in the gas phase and (ii) diffusion and etching of the silicon.