XANES and XPS characterization of hard amorphous CSi x N y thin films grown by RF nitrogen plasma assisted pulsed laser deposition

Abstract

Amorphous carbon silicon nitride thin films were grown on (100) oriented silicon substrates by pulsed laser deposition (PLD) assisted by an RF nitrogen plasma source. Up to about 30 at. % nitrogen and up to 20 at. % silicon were found in the hard amorphous thin films by XPS in dependence on the composition of the mixed graphite / Si 3 N 4 PLD target. The universal nanohardness was measured to be at maximum load force of O. mN up to 23 GPa for thin CSi x N y films with reference value of 14 GPa for single crystalline silicon. X-ray photoelectron spectroscopy (XPS) of CSi x N y film surfaces showed a clear correlation of binding energy and intensity of fitted features of N 1s, C 1s, and Si 2p peaks to the composition of the graphite / Si 3 N 4 target and to nitrogen flow through the plasma source, indicating soft changes of binding structure of the thin films due to variation of PLD parameters. Auger electron spectroscopy (AES) of Si KL 23 L 23 ; 1 D Auger transition gave a detailed view of bonding structure of Si in the CSi x N y films. The intensity of π * and σ * resonances at the carbon K-edge X-ray absorption near-edge structure (XANES) of the CSi x N y films measured at BESSY I corresponded to the nanohardness of the CSi x N y films, thus giving insight into chemical binding structure of superhard amorphous materials.