Chemical composition of ZrC thin films grown by pulsed laser deposition

Abstract: ZrC films were grown on (100) Si substrates by the pulsed laser deposition (PLD) technique using a KrF excimer laser working at 40Hz. The nominal substrate temperature during depositions was set at 300°C and the cooling rate was 5°C/min. X-ray diffraction investigations showed that films deposited under residual vacuum or under 2×10−3 Pa of CH4 atmosphere were crystalline, exhibiting a (200)-axis texture, while those deposited under 2×10−2 Pa of CH4 atmosphere were found to be equiaxed and with smaller grain size. The surface elemental composition of as-deposited films, analyzed by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS), showed the usual high oxygen contamination of carbides. Once the topmost 2–4nm region was removed, the oxygen concentration rapidly decreased, down to around 3–8% only in bulk. Simulations of the X-ray reflectivity (XRR) curves indicated a smooth surface morphology, with roughness values below 1nm (rms) and films density values of around 6.30–6.45g/cm3, very close to the bulk density. The growth rate, estimated from thickness measurements by XRR was around 8.25nm/min. Nanoindentation results showed for the best quality ZrC films a hardness of 27.6GPa and a reduced modulus of 228GPa. [Copyright &y& Elsevier]