Atomic layer deposition (ALD) of zinc oxide (ZnO) films on (0 0 0 1) sapphire substrates was conducted at low temperatures by using diethyl-zinc (DEZn) and nitrous oxide (N2O) as precursors. It was found that a monolayer-by-monolayer growth regime occurred at 300 degrees C in a range of DEZn flow rates from 5.7 to 8.7 mu mol/min. Furthermore, the temperature self-limiting process window for the ALD-grown ZnO films was also observed ranging from 290 to 310 degrees C. A deposition mechanism is proposed to explain how saturated growth of ZnO is achieved by using DEZn and N2O. Transmission spectroscopic studies of the ZnO films prepared in the self-limiting regime show that the transmittances of ZnO films are as high as 80% in visible and near infrared spectra. Experimental results indicate that ZnO films with high optical quality can be achieved by ALD at low temperatures using DEZn and N2O precursors. (C) 2009 Elsevier B. V. All rights reserved.