Characteristics of Cr-Al-N-O thin films prepared by pulsed laser deposition

Chromium aluminum oxynitride (Cr-Al-N-O) thin films have been successfully prepared by pulsed laser deposition (PLD). Experiments were carried out by changing surface area ratio of the targets (SR = SAIN/(SCr2N+ SAIN) from 0 to 100 %. The hardness of one of the Cr-Al-N-O thin films was found to be approximately 40 GPa when the aluminum content in cations (x) was 35 at. %. Elastic modulus of the Cr-Al-N-O thin films with x = 35 at. % was clarified to be 40 % higher than that of chromium oxynitride (Cr-N-O) thin film. These results implied that increasing the elastic modulus by substitution of Al for Cr in Cr-N-O grains causes the hardening of the Cr-Al-N-O thin films. In oxidation tests, the existence of oxides was not detected in the Cr-Al-N-O thin film heat-treated at 900 °C by X-ray diffraction (XRD). This fact was presumed to be due to dissolved aluminum atoms in Bl (NaCl) structure.