Surface characterisation of laser irradiated SiC ceramics by AES and XPS

Samples of sintered silicon carbide (SSiC) were irradiated with a KrF excim er laser (lambda = 248 nm) at energy densities of 10, 15 and 25 J/cm(2) in He atmosphere. The composition of the near surface region was investigated by Auger electron spectroscopy (AES) and photoelectron spectroscopy (XPS) a fter lapping, laser irradiation and tribological treatment, respectively. B y laser irradiation a surface layer is formed which contains about 30% oxyg en. The existence of different bonding states of Si, C and O was establishe d by factor analysis of the AES depth profiles and by XPS. By laser irradia tion SIC is decomposed and a siliconoxycarbide with the average composition SiC3.5O1.5 is formed. Beneath the oxidised surface layer the nominal eleme ntal composition SiC is found but the sample represents a mixture of Si, gr aphite and siliconoxycarbide with a small amount of SiC only. Obviously, th e decomposition zone exceeds in a depth > 300 nm.