Correlations between 1/f noise and thermal treatment of Al-doped ZnO thin films deposited by direct current sputtering

Al-doped ZnO thin films (AZO) have been deposited on amorphous glass substrates by DC sputtering at different substrate temperatures T-s. X-Ray diffraction results reveal that AZO thin films have a hexagonal wurtzite structure with (002) preferred orientation. (002) peaks indicate that the crystalline structure of the films is oriented with c-axis perpendicular to the substrate. Three-dimensional (3D) atomic force microscopy images of AZO thin films deposited on glass substrate at 200 degrees C, 300 degrees C, and 400 degrees C, respectively, shows the improvement of the crystallinity and the homogeneity of AZO thin films with T-s which is in agreement with the noise measurements. The noise was characterized between 1 Hz and 100 kHz and we have obtained 1/f spectra. The noise is very sensitive to the crystal structure especially to the orientation of the crystallites which is perpendicular to the substrate and to the grain boundaries which generate a high current flow and a sharp increase in noise. Through time, R-sh and [alpha,mu](eff) increase with the modification of the crystallinity of AZO thin films. Study of noise aging shows that the noise is more sensitive than resistivity for all AZO thin films. (C) 2014 AIP Publishing LLC.