The authors report a strong dependence of fiber texture tilt angle on the gas composition in aluminum nitride (AIN) thin films prepared by off-normal reactive magnetron sputtering in N-2/Ar mixtures. Using x-ray pole figures, they measured the c-axis AIN tilt angle as a function of N-2 flow ratio for a deposition angle of 42 degrees from normal. They found that the c axis remains perpendicular to the substrate for a N-2 flow ratio up to 12%-15% and then abruptly shifts towards the deposition direction for a N-2 flow ratio above 12%-15%. They also identified a range of deposition parameters at lower N-2 flow in which an amorphous phase of AIN is formed. The authors attribute the tilted fiber texture to the energetic atom flux causing less damage and resputtering in grains oriented with open channeling directions, compared with nonchanneling directions in AIN. The abrupt change in fiber tilt angle versus gas composition is attributed to the adatom mobility being quenched above 12%-15% N-2 flow. (c) 2007 American Vacuum Society.