(Bi, La)3Ti4O12 (BLT) thin films were prepared on various sized Pt-coated Si (Pt/Ti/SiO2/Si(100)) substrates by chemical solution deposition method. The crystalline orientation of BLT thin films is drastically changed by the substrate size. c-axis preferentially oriented films were obtained on larger, 30 mm square, substrates. On the other hand, randomly oriented films were obtained on smaller, 10 mm square, substrates. The surface morphology of randomly oriented BLT thin films deposited on a 10 mm square substrate showed rod shape grains which lying along random directions. On the other hand, c-axis oriented BLT thin films which were deposited on 30 mm square substrate showed a layered structure. The remnant polarization and coercive field of BLT thin films deposited on 10, 15, 20 and 30 mm square substrates measured at 360 kV/cm are 14.3, 16.0, 8.24, and 8.79 μC/cm2; 60.1, 81.4, 80.4 and 78.6 kV/cm, respectively.
Epitaxial barium hexaferrite [BaFe12O19 (BaM)] thin films were grown on YSZ-buffered Si(001) substrates using a PLD apparatus in which an electromagnet had been installed (dynamic aurora PLD). We examined the effects of applying a magnetic field (up to 2 kG) on the crystal structure and magnetic properties during deposition. The application of the magnetic field during deposition had little effect on the orientation, residual strain, and Curie temperature of BaM thin films. However, the crystallinity and saturation magnetization of the films were lowered. Possible reasons for the lowering of saturation magnetization are discussed.
(001) oriented epitaxial Pt bottom electrode was prepared on Si(001) substrate using four fold buffer layer of ST/LSCO/CeO 2 /YSZ. On the epitaxial Pt bottom electrode, we found that both epitaxial and polycrystalline BST thin film can be prepared by the change of oxygen gas flow procedure during heating up to deposition temperature of BST. Without oxygen gas flow on the heating process of the Pt bottom electrode, BST thin film was changed into polycrystalline, on the other hand, when the Pt bottom electrode was heated in 100 mTorr of oxygen pressure, epitaxial grown BST thin film was realized. This means that the orientation of BST thin film can be controlled by the oxygen flow procedure during heating of the Pt bottom electrode. Dielectric constant and tunability of epitaxial BST thin film changed with the oxygen pressure during heating and deposition of BST thin film. This suggests that oxygen pressure during heating and deposition is the key to control the orientation and properties of BST thin film.
Low temperature crystallization of CSD-derived ferroelectric thin films was aimed by laser assisted annealing in this paper. Pb(ZrxTi1-x)O3(PZT) thin films with a MPB composition (Zr/Ti = 53/47) and LaNiO3 (LNO) thin film electrodes were deposited by the chemical solution deposition (CSD) method on a Si wafer. The thickness of PZT films was about 70 nm, and the thickness of LNO films as seeding layers and electrodes was about 250 nm. The PZT/LNO films were annealed at the substrate temperature ranging from 300°C to 500°C for 15 min with or without KrF excimier laser irradiation. Both the diffraction peaks of (100)- and (200)- planes for PZT and LNO were identified at 500°C. However, (100)- and (200)- peaks for PZT were not observed for the films without laser-irradiation below 400°C. On the other hand, these peaks were observed for the PZT films with laser-irradiation even below 400°C. The dielectric constant of the PZT film with laser assisted annealing at 350°C was measured to show about 700. These results demonstrated that the crystallization of ferroelectric PZT thin films was enhanced by KrF excimier laser irradiation and by using the oriented LNO thin film as a seeding layer.
InN, one of III–V group compounds, has attracted attention owing to its optical properties in the infrared region. A high quality crystal growth for InN, however, is a key issue because InN is unstable at high temperature due to its thermal instability. Moreover, a microstructure control of InN by controlling a growth condition is desired for various optical applications. Atmospheric pressure halide chemical vapor deposition (APHCVD) method enables a single-crystal growth of InN at moderate growth temperature. In the present study, influence of the growth temperature and time on microstructure of hexagonal-pillar-structure InN single crystals by the APHCVD method on sapphire (1120) substrate is investigated using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The growing temperature of the InN influences significantly to the microstructure of the InN crystal; flower like structures at low temperature of 560 °C, pillar structures at moderate temperature of 590 to 610 °C, and coalesced pillar structure at 640 °C.
