Growth of ZnO x :Al by high-throughput CVD at atmospheric pressure

Abstract: Aluminum doped zinc oxide films (ZnO x :Al) have been deposited on a moving glass substrate by a metalorganic CVD process at atmospheric pressure in an in-line industrial type reactor. Tertiary-butanol has been used as an oxidant for diethylzinc and trimethylaluminium as the dopant gas. The effect of the deposition temperature (from 380 to 540°C) on the deposition rate has been investigated by a numerical code, where a gas phase reaction among tertiary-butanol and diethylzinc is assumed to occur. The structural (crystallinity and morphology) properties of the films as a function of the deposition temperature have been analyzed by using X-ray diffraction and Scanning Electron Microscopy. A maximum growth rate of ∼11nm/s was found at a deposition temperature of 480°C, for which ZnOx:Al films show (002) preferential orientation, good crystalline quality and a naturally rough surface. ZnO x :Al films deposited at 480°C are also highly conductive (R<10Ω/□ for film thicknesses above 1050nm) and transparent (>85% in the visible range). These films have been used as front transparent conductive oxide layers in pin a-Si:H solar cells, achieving an initial efficiency approaching 8%. [Copyright &y& Elsevier]