Al2O3 films with thicknesses ranging from 30 to 3540 A were grown in a viscous flow reactor using atomic layer deposition (ALD) with trimethylaluminum and water as the reactants. Growth temperatures ranged from 125 to 425 degreesC. The Al2O3 ALD films were deposited successfully on a variety of substrates including An, Co, Cr, Cu, Mo, Ni, NiFe, NiMn, Pt, Ptmn, Si, stainless steel, W, and ZnO. Electrical properties were characterized by current-voltage and capacitance-voltage measurements using a mercury probe. These measurements focused mainly on Al2O3 ALD films deposited on n-type SiO(100) and on Mo-coated SiO(1 0 0) substrates. Excellent insulating properties were observed for nearly all of the Al2O3 films. For a typical Al2O3 ALD film with a 120 Angstrom thickness, leakage currents of < I nA/cm(2) were observed at an applied electric field of 2 MV/cm. Fowler-Nordheim tunneling was observed at high electric fields and dielectric breakdown occurred only at greater than or equal to5 MV/cm. Dielectric constants of ksimilar to7.6 were measured for thick Al2O3 ALD films. The measured dielectric constant decreased with decreasing Al2O3 film thickness and suggested the presence of a thin interfacial oxide layer. For Al2O3 ALD films grown on n-type Si(I 0 0), capacitance measurements were consistent with an interfacial layer with a SiO2 equivalent oxide thickness of 11 Angstrom. Spectroscopic ellipsometry investigations also were in agreement with a SiO2 interfacial layer with a 13 Angstrom thickness.