Microstructure, opotoelectrical and pre-strain dependent electrical properties of AZO films on flexible glass substrates for flexible electronics

Al-doped zinc oxide (AZO) thin films were deposited on ultra-thin flexible glass substrate using a direct current magnetron sputter. Microstructure, electrical and optical properties of the AZO films were investigated as a function of film thickness. The XRD pattern shows that all deposited AZO films have a highly preferred c-axis orientation along (0002) direction. When the film thickness is over 100 nm, all the AZO films have similar grain size about 30 nm and good uniformity. The sheet resistance of the AZO films decreased with the increase of film thickness, whereas the 230.1 nm thick AZO film has the minimum resistivity of 1.65 × 10− 3 Ω cm. The average transmittance of all AZO films in the visible range was about 80%, while the optical band gap of the films was in the range of 3.483-3.526 eV. The sheet resistance of AZO films deposited on flexible glass using strained growth is different with that of AZO films using normal growth method. Moreover, the sheet resistances of AZO film with different pre-strain are very different, which may be due to their different microstructures of AZO films.