HFCVD diamond growth on Cu(111). Evidence for carbon phase transformations by in situ AES and XPS

Polycrystalline diamond has been deposited on monocrystalline Cu(111) via the hot filament chemical vapour process. The diamond growth was studied by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS), directly connected to the growth chamber. Shape analysis of the AES C KVV line and C 1s relative intensity both suggest the following three-step process: first the formation of two graphite layers, then the very slow growth of graphitic layers, more and more distorted when going away from the copper surface and finally, when a critical size corresponding to ca five to six layers is reached, diamond nucleation and growth. A very long induction time (> 10 h) is observed before the growth of graphitic layers. This is ascribed to the strong interaction of the graphite layer with the copper surface. Transmission electron microscopy and selected area diffraction confirm this process, but in addition reveal the presence of small spherulitic (onions) and polyhedral graphite-like aggregates. This nucleation process is roughly in agreement with the recrystallization model of diamond nucleation from amorphous carbon proposed by Singh and Vellaikal, J. Appl. Phys. 73 (1993) 2831.