STRUCTURAL AND OPTICAL PROPERTIES OF ZnO THIN FILMS GROWN ON FLEXIBLE POLYIMIDE SUBSTRATES

Nominally undoped ZnO thin films were grown on polyimide (PI) substrates at various temperatures by using radio-frequency magnetron sputtering. Atomic force microscopy images showed that the root mean squares of the average surface roughnesses for the ZnO thin films grown on the PI substrates at 27°C, 100°C, 200°C, and 300°C were 4.08, 4.50, 4.18, and 3.89 nm, respectively. X-ray diffraction patterns showed that the crystallinity of the ZnO films had a preferential (0001) direction and that the full width at half-maxima for the (0002) ZnO diffraction peak for the ZnO thin films grown on the PI substrates at 27°C, 100°C, 200°C, and 300°C were 0.22, 0.22, 0.22, and 0.23, respectively. The average optical transmittances in the visible ranges between 550 and 750 nm for the ZnO/PI heterostructures grown at 27°C, 100°C, 200°C, and 300°C were 87%, 83%, 87%, and 78%, respectively.