Effect of post-annealing on the physical and electrical properties of LaAlO3 gate dielectrics

A novel high-k dielectric amorphous LaAlO₃ (LAO) film was deposited by laser molecular beam epitaxy technique directly on silicon substrates. Effect of post-annealing on the physical and electrical properties of LAO films has been studied. X-ray diffraction observations indicate that the films can remain amorphous structure after rapid thermal processing at temperature up to 1000°C for five minutes. However, the films begin to crystallize when receiving long time furnace annealing. High-resolution transmission electron microscopy images show that interfacial reaction between LAO film and Si often occurs when annealing in oxygen ambient. For films annealed in nitrogen ambient, no clear interfacial reaction can be found. Electronic structures of LAO film change when films annealed in nitrogen ambient. Effective oxide thickness of the Pt/LAO/Si stack increases with increase of annealing time and the corresponding leakage current density decreases with increase of annealing time.