Surface dynamics transition during the growth of compositionally graded CrN_x films

We report a direct experimental study on the surface dynamics of reactive-sputtered compositionally graded (CG) CrN_x films. Based on the dynamic scaling analysis, an intriguing transition of surface dynamics from Family-Vicsek scaling (I regime) to "oscillating" mode (II regime) and then to anomalous rapid-roughening scaling (III regime) is observed. This transition is closely related to the reactive sputtering process of CG nitride films. Especially, it is found that the oscillating behavior of surface dynamics in regime II originates from the alternate growth of crystalline and amorphous phases on the growing surface.