A dielectric film containing HfAlO.sub.3 and a method of fabricating such a dielectric film produce a reliable gate dielectric having an equivalent oxide thickness thinner than attainable using SiO.sub.2. A gate dielectric is formed by atomic layer deposition employing a hafnium sequence and an aluminum sequence. The hafnium sequence uses HfCl.sub.4 and water vapor. The aluminum sequence uses either trimethylaluminum, Al(CH.sub.3).sub.3, or DMEAA, an adduct of alane (AlH.sub.3) and dimethylethylamine [N(CH.sub.3).sub.2(C.sub.2H.sub.5)], with distilled water vapor. These gate dielectrics containing a HfAlO.sub.3 film are thermodynamically stable such that the HfAlO.sub.3 film will have minimal reactions with a silicon substrate or other structures during processing.