A comparative study of growth and properties of atomic layer deposited transparent conductive oxide of Al doped ZnO films from different Al precursors

Abstract Transparent conducting oxide of Al-doped ZnO (AZO) films were prepared by atomic layer deposition (ALD) using diethylzinc (DEZ) and 3 kinds of Al precursors, including trimethylaluminum (TMA), aluminum isopropoxide (AIP) and AlCl 3 . The impact of ZnO/Al 2 O 3 cycle ratios from 9:1 to 39:1 and Al precursors on the growth rate, Al dopant concentration, structure, and resistivity of AZO films were investigated deeply. At the same ZnO/Al 2 O 3 cycle ratio, the film thickness decreases and the Al dopant concentration increases gradually with TMA, AIP and AlCl 3 precursors in turn. Generally, the Al doping leads to poorer crystallinity and better conductivity for AZO films. Both TMA-AZO and AIP-AZO films with 19:1 ZnO/Al 2 O 3 cycle ratio show the lowest resistivity of 3.3–4 × 10 − 3  Ω cm with Al doping content of 2.1% and 2.3%, respectively, which can be well explained by the effective field model. Additionally, all the AZO films exhibit great optical transparency of > 85% for wavelengths of 370–900 nm.