Iron-Catalyzed Growth of Vertical Graphitic Layers on the (100) Face of Single-Crystal Diamond

The transformation of diamond into graphite occurs at elevated temperatures, and by controlling this process, sp2/sp3 carbon hybrids can be created. In this work, we study the effect of a thin iron film coating on the reconstruction of a (100) diamond face. We use a synthetic single-crystal and anneal it in ultrahigh vacuum at 1150 °C for 15 min. The electronic state of carbon on a clean face and a coated face is immediately examined by X-ray photoelectron spectroscopy and angle-dependent near-edge X-ray absorption fine structure spectroscopy. Raman spectroscopy and scanning electron microscopy measurements complete the structural characterization of the annealed sample. An analysis of the experimental data reveals the formation of thin sp2-carbon fragments on a clean (100) diamond surface and ordered graphite planes on the iron-coated surface. According to our estimates, iron catalyzes the transformation of roughly 10 nm diamond into graphitic layers growing vertically relative to the (100) face of the diamond.