Deposition conditions and HRTEM characterization of CAAC IGZO

Crystallinity and texture of c-axis aligned crystal indium gallium Une oxide (CAAC IGZO) films deposited by RF reactive sputtering were studied and characterized over a range of deposition conditions. The characteristic CAAC (009) peak at 20=30° was observed by X-ray diffraction, and nanocrystalline domain texture was determined using a general area detector diffraction system (GADDS). Highly ordered CAAC films were obtained near the InGaZnO₄ composition at a substrate temperature of 310°C and in 10% O₂. High-resolution transmission electron microscopy (HRTEM) confirmed the formation of CAAC showing 2-3 nm domains aligned over 15 nm × 15 nm fields of view. Cross-section HRTEM of the CAAC/substrate interface shows formation of an initially disordered IGZO layer prior to CAAC formation, suggesting a nucleation mechanism similar to ZnO thin films.