Highly conductive air stable ZnO thin film formation under in situ UV illumination for an indium free transparent electrode
Zinc oxide (ZnO) is considered as the strongest alternative to tin doped indium oxide (ITO) a commonly used, but an expensive state of the art material for transparent conducting electrodes. This work reports the low temperature atomic layer deposition (ALD) of a highly transparent, and highly conductive air stable thin film of ZnO under in situ UV irradiation of the growing film. X ray photoelectron spectroscopy (XPS) reveals that the UV irradiation generates oxygen vacancies, partially removes O H bonds, and thereby improves the electrical conductivity. Thus, in contrast to 0.25 O cm resistivity of the pristine ZnO film, the in situ UV irradiated ZnO film shows an electrical resistivity of 5.5 x 10 4 O cm, and an optical transparency of nearly 90% which are closer to that of ITO. In addition, even on prolonged exposure of the film to air, it demonstrates high stability against the degradation of the electrical conductivity.