This paper discusses the correlations between growth conditions and electrical, structural and optical properties of zinc oxide thin films grown at low temperature by Atomic Layer Deposition (ALD) method from diethylzinc (DEZn) and deionized water. The surface morphology and microstructure of ZnO layers were studied with Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and X‐ray Diffraction (XRD) techniques. The electrical and optical properties of samples were examined by performing room temperature Hall effect and photoluminescence (PL) measurements. These investigations and Electron Dispersive X‐ray (EDX) analysis revealed that changes of the growth conditions (growth temperature, number of ALD cycles (layer thickness)) enable us to control the free electron concentration in as‐grown ZnO layers in the range of 1017 – 5×1019cm–3, which is related to the changes in structural properties and stoichiometry of the films (defect concentration, grains' sizes). (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)