Aluminum oxide films grown on silicon substrates by the ML-ALE method were studied. The structures were grown from trimethyl aluminum (TMA), H₂O and NO₂ at temperatures in the range of 150 to 310°C. These films were characterized by refracting index n = 1.68 + 0.02 (λ = 632.8 nm) and relative permittivity ε{lunate} = 5.3 + 0.2 (f = 1 MHz). Electro-physical characteristics of these layers were measured in metal-insulator-semiconductor (MIS) and electrolyte-insulator-semiconductor (EIS) systems. The threshold voltage of the MIS structure with Al gate was about 7.5 MV/cm. The Si-Al₂O₃ structures had both electron and hole traps. It was found that increasing the synthesis temperature leads to a decrease of the concentration of electron traps and to an increase of hole traps. So it was shown that the ML-ALE method made it possible to grow Si-Al₂O₃ structures similar to the well known Si-Si₃N₄ structures. Si-Al₂O₃ structures may be used in electronic devices.