Plasma enhanced chemical vapor deposition of thin ZnO layers at low temperatures

The plasma enhanced chemical vapor deposition (PECVD) is a powerful and flexible instrument for depositing thin layers, nanocomposites or nanostructures. In this work, thin ZnO layers have been grown by PECVD (RF - 13.56 MHz) on optical glasses (BK7), Si wafers and polycarbonate (PC), at a substrate temperature of∼40°C. Zn acetylacetonate contained in a resistively heated Knudsen cell has been used as a precursor, and oxygen as an oxidant. A system for dosed injection of the precursor and oxidant into the plasma reactor has been developed. The influence of the RF power and oxygen pressure on the composition, structural and optical properties of the ZnO layers has been studied. The results show that the carbon content in the layers decreases, and more Zn atoms are bound to oxygen, with increasing RF power and oxygen pressure. The layers obtained at the highest RF power and O 2 gas ambient pressure were amorphous, with high optical transmission in the visible region and and Eg of 3.36 eV, which is very close to that of bulk ZnO material. These characteristics make the layers suitable for applications as transparent windows for the visible and infrared regions, and as optical filters for the UV region.