Influences of different buffer layers on Al-doped ZnO flims deposited by RF magnetron sputtering

In order to get high transparent and conductive Al-doped ZnO (AZO) films at room temperature, an off-axis RF magnetron system and i-ZnO buffer layer were introduced to deposit AZO thin films. By varying the deposition time of i-ZnO, we studied the crystal, structural, optical and electrical properties of the the AZO films as a function of the buffer layer's thickness. The samples showed good crystallinity with sharp (002) peak and smooth surface morphologies. The appearance of micropits and the films' thickness versus time revealed the buffer layer not only helped to release the stress but also offered a template for the AZO films to grow. As shown in SEM cross-sectional images, the films can be separated into bottom layer, main body and upper layers, indicating a structure revolution. With the thickness of about 500nm, the AZO films had transmittance above 85% in the visible region and resistivity as low as 1.0·10^-3 Ω·cm.