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.