Direct ion beam sputter deposition of AlN is studied using both pure nitrogen and a 75% N-2 + 25% H-2 mixture as the feed gas for the ion gun. The chemical characteristics of these films are probed using infrared spectroscopy, atomic force microscopy, optical microscopy, and chemical etching. The presence of Al-N-2 species is associated with reactive and highly defective films. The presence of NHx species produces an increase (by several orders of magnitude) in the rate at which AlN films are etched by base. However, stoichiometric and low-defect AlN films prepared by depositing AlN:H onto substrates heated to 200 degrees C have reactivities similar to the best AIN films produced in the absence of hydrogen. For the stoichiometric AlN films, the following etch rates were observed : 8 nm min(-1) in 1.0 M NaOH at 22 degrees C; 14 nm min(-1) in 85% phosphoric acid at 75 degrees C.