Characterization of reactively sputtered c-axis aligned nanocrystalline InGaZnO₄

Crystallinity and texturing of RF sputtered c-axis aligned crystal InGaZnO₄ (CAAC IGZO) thin films were quantified using X-ray diffraction techniques. Above 190°C, nanocrystalline films with an X-ray peak at 2θ=30° (009 planes) developed with increasing c-axis normal texturing up to 310°C. Under optimal conditions (310°C, 10% O₂), films exhibited a c-axis texture full-width half-maximum of 20°. Cross-sectional high-resolution transmission electron microscopy confirmed these results, showing alignment variation of ±9° over a 15 × 15nm field of view and indicating formation of much larger aligned domains than previously reported. At higher deposition temperatures, c-axis alignment was gradually lost as polycrystalline films developed.