Al-doped ZnO (AZO) thin films (~100nm) with low electrical resistivity and high transparency have been prepared by atomic layer deposition on glass and Si(111) substrates at 200 °C with different doping sequence. The films were systematically analyzed using X-ray diffraction, scanning electron microscope (SEM), UV-vis spectroscopy and Hall measurement. XRD patterns showed that all the films were well crystallized with hexagonal wurtzite structure with preferred orientation along (100) plane. The resisitivity of films deposited with doping sequence of DEZ/TMA/H2O was lower than that with other doping sequences. Results from SEM showed a worm-like shape and similar grain sizes of AZO films. Optical transparency of AZO films was measured to be >90% for wavelengths of 400-1000 nm.