Morphological and ferroelectric studies of Li-doped ZnO thin films

Li-doped ZnO films were grown on glass substrates by ultrasonic spray pyrolysis (pyrosol) and chemical bath deposition (CBD) methods. A comparative study was performed on the effect of Li doping (0-40 at%) on the morphology and ferroelectric properties of such as-grown films. Structural investigations revealed that, in both cases, high-quality layers were grown with the wurtzite structure and c-axis preferred crystalline orientation. The surface morphology and grain structure depended on the deposition process as well as the physical properties induced by Li-doping. The temperature during the initial stage of the growth appeared as an important parameter. Ferroelectricity in Li-doped ZnO films could be observed only for the lower-temperature CBD process in which diffusion phenomena at the film/substrate interface were limited.