Spatial Atomic Layer Deposition of Zinc Oxide Thin Films

Zinc oxide thin films have been deposited at high growth rates (up to similar to 1 nm/s) by spatial atomic layer deposition technique at atmospheric pressure. Water has been used as oxidant for diethylzinc (DEZ) at deposition temperatures between 75 and 250 degrees C. The electrical, structural (crystallinity and morphology), and optical properties of the films have been analyzed by using Hall, four-point probe, X-ray diffraction, scanning electron microscopy, spectrophotometry, and photoluminescence, respectively. All the films have c-axis (100) preferential orientation, good crystalline quality and high transparency (similar to 85%) in the visible range. By varying the DEZ partial pressure, the electrical properties of ZnO can be controlled, ranging from heavily n-type conductive (with 4 mOhm.cm resistivity for 250 nm thickness) to insulating. Combining the high deposition rates with a precise control of functional properties (i.e., conductivity and transparency) of the films, the industrially scalable spatial ALD technique can become a disruptive manufacturing method for the ZnO-based industry.