Unskimmed, pulsed hyperthermal molecular beams of trimethylaluminum (TMA) and ammonia were used to grow films of aluminum nitride, The crystal structure of the films was determined by X-ray diffraction (XRD). AlN was deposited on Si(1 0 0) and AlN-Si. The AIN-Si samples consist of 1 mu m layer of MOCVD-grown polycrystalline AlN on Si(1 0 0) substrates. The resulting film orientation on Si(1 0 0) is with the AIN(1 0 (1) over bar 0) plane parallel to the substrate plane. On AIN-Si substrates, the AIN(1 0 (1) over bar 0) plane is still. prevalent. The effect of varying the precursors' azimuthal angle of incidence, alpha, was also investigated. AlN was grown on Si(1 0 0) at alpha = 0, 30, 60 degrees. For alpha > 0, the AlN(1 0 (1) over bar 0) and AlN(1 0 (1) over bar 1) planes are present. At alpha = 60 degrees, weak X-ray diffraction peaks indicate the films have short-range order. For the ct examined, the average growth rate is approximately 0.35 mu m/h. AES was used for chemical analysis of films.