HIGH TEMPERATURE X-RAY DIFFRACTION STUDY OF PbTiO_3 THIN FILMS GROWN ON MgO(001) BY MOCVD

摘要

Lead titanate (PT) is ferroelectric in its tetragonal phase (c/a=1.06). The domain formation is coupled to the relaxation of internal stress generated by a combination of lattice mismatch, transformation strain and differential thermal stress. The mechanism of domain formation in an epitaxially grown PT film is related to the substrate type and the growth temperature. In this study, PT films have been deposited on MgO(001) in a cold-wall, horizontal metal organic chemical vapor deposition (MOCVD) system. The structure of domains and their evolution have been measured as a function of temperature by the x-ray diffraction method using a hot stage. Domain structure changes were observed by #theta#-2#theta# scans, #omega# scans, as well as in-plane #phi# scans. Effect of film stress on the ferroelectric transition temperature is discussed. Reproducibility of domain formation as a result of temperature cycling both below and above T_c is assessed.