The deposition of Al2O3 thin films by atomic layer epitaxy was investigated using Al(CH3)2Cl as a new aluminum precursor. All the films grown in the temperature range of 125–500 °C were amorphous as examined by x-ray diffraction analysis. The residual contents of carbon, chlorine, and hydrogen in the film deposited at 200 °C were 0.2, 2.1, and 12 at. %, respectively, and diminished rapidly with increasing growth temperature. The refractive index of the films increased with deposition temperature, stabilizing at the highest value of 1.68 above 300 °C. The permittivity of the films increased from 7.3 to 8.7 with increasing growth temperature from 200 to 500 °C. The leakage current density was lowest in the film deposited at 200 °C and increased markedly at higher deposition temperatures. © 1997 American Vacuum Society.