Bismuth Titanate Ferroelectric Thin Films And Its Compound Semiconductor Substrate, X-ray Diffraction

As the rapid development of micro-electronics and integrated circuit technology, one needs to integrate various micro-scale materials with different functions onto a board to form a variety of outstanding performance composite material system. Therefore, the ferroelectric thin films and the semiconductor substrates have attraccted great attentions all over the world.Due to the lattice mismatch and thermal mismatch between the thin film and the substrates, residual stress will be inevitably induced into the films, and the residual stress may lead the crack, delamination or completely failure of the thin films. The researches of GaN are almost on GaN films epitaxial grown on sigle crystal substrates, and the epitaxial growth process will inevitable bring out structural defects. These defects can seriously affect the performance of GaN thin films, thus affecting the GaN-based devices. On the other hand, if the introduction of the residual stress is fully understood and the deffects of the semiconductor substrates are fully studied, one can make good use of the strain to modulate and improve the ferroelectric thin films, and improve the semiconductor substrates by defects controll. Therefore, the studies of the stresses in the ferroelectric films and the deffects in the semiconductor substrates is very important.In the Introduction of this master thesis, the potential applications, preparation methods and the current studies of doped Bi4Ti3O12 films and GaN films are reviewed. On the basis of the review, the investigation of the structure-properties of doped Bi4Ti3O12 films and GaN films by X-ray diffraction methods is proposed. Main content of the thesis are also given in the Introduction.The thesis focused on the stresses analysis of Bi4Ti3O12(BIT) films deposited on Si and Hf 4 +doped Bi4Ti3O12(BTH) deposited on SrTiO3 using curvature radius and reciprocal space mappings(RSM). Also various measure methods are used to analyze the obtained results of stresses and structures. Then the relationships among the stresses, microstructure and properties are discussed. In the study of BIT films deposited on Si, the stresses and the orientations of the films were directly affected by the depositing temperature of the self-buffer. In the study of BTH films deposited on SrTiO3, the results showed that the doped Hf 4 +changed the domain structure and the strain obviously, and the larger remnant polarization of BTH film were successfully explained combined with those changes. At last, the defect structures of GaN films with AlN and without AlN were studied by HRXRD(High Resolution X-ray diffraction).These results obtained in these researches are complementary to the current study on Bi-layered structure films and the GaN substrate of the integration of ferroelectric materials and semiconductor materials.