Chromium oxyniride (Cr(N, O)) thin films have been successfully prepared by using pulsed laser deposition (PLD). Oxygen content in the thin films (x) was controlled by changing experimental conditions, and x of each thin film was determined to be 8, 14, 28 and 30 at.% by using Rutherford backscattering spectroscopy. The hardness of thin films was measured by Vickers hardness tester. The hardness of Cr(N, O) thin films increased with increasing x. Furthermore, morphology observation by the result of transmission electron microscope, the marked grain refinement was not observed by addition of oxygen to CrN.
