Crystalline character transition from amorphous to polycrystalline phase during La₂O₃ films growth using pulsed laser deposition

We have observed crystalline characteristics of high k dielectric La₂O₃ films transferring from amorphous to polycrystalline phase on Si substrates during the film growth using pulsed laser deposition method. During the film growth, reflection high-energy electron diffraction was used to monitor the growth phase transitions; it shows that initial crystalline patterns change to other at a certain time. In depth studies with transmission electron microscope exhibit clear formation of polycrystalline La₂O₃ layers on ~10 nm amorphous La₂O₃. Interestingly, no interfacial oxide layer between the Si substrate and the La₂O₃ film is formed. The amorphous phase turns out not from the interfacial mixing of Si and La₂O₃ layers. Rather, abrupt transition from amorphous to polycrystalline phase in La₂O₃ films is attributed to material’s growth nature.