Multimode AFM analysis of aluminum-doped zinc oxide thin films sputtered under various substrate temperatures for optoelectronic applications

Abstract

Here we present an in-depth atomic force microscopy study of aluminum-doped zinc oxide (AZO) thin films utilizing various modes (topology, phase and error signal) together with image processing techniques including skew, kurtosis, entropy, autocorrelation and fractal analysis. Fractal dimension has been calculated via cube counting, triangulation, power spectrum and partitioning methods. A correlation has been found between the micromorphological properties and the functional properties of the AZO transparent conducting oxide when annealed at different temperatures. Structural, electrical, morphological and optical properties of AZO thin films were investigated by XRD, 4-Point-probe, AFM and UV-VIS spectroscopy. The results indicate that the AZO thin film properties are affected by substrate temperature. An optimum figure of merit of 1.518×10−3Ω−1 is obtained for a substrate temperature of 150°C. It is expected that this work can provide a novel approach towards optimization of transparent conducting oxides, in particular with regards to plasmonics.