Effect of the Initial Surface State of Silicon on Nucleation and Growth of Diamond CVD: An Investigation by Electron Spectroscopies

Abstract

Diamond has been deposited by hot filament CVD at a high methane concentration in hydrogen (2%) on three model surfaces generated from the same (311)-oriented silicon sample: (i) clean silicon Si, (ii) silicon carbide SiC layer preformed by carburization and (iii) as-received sample covered with oxydized silicon SiOx (x ≤ 2) (thickness ≈︂20 Å) as well as amorphous carbon or hydrocarbon. Short time deposits were achieved to provide information about intermediate products and structural modifications of both carbon and silicon. Auger electron spectroscopy (AES) and loss electron spectroscopy (ELS) have been used for the characterization of the carbon deposits in a UHV chamber directly connected to the reactor chamber. Almost immediately, we note similar evolution of the carbon deposit for the three model surfaces revealed by the line shape modifications of C KVV Auger transition and the loss peak positions. Surface oxide, if present, is removed and silicon carbide is formed followed by carbon growth. However, on the last surface, strong surface amorphization of the silicon as well as carbon π states were observed.