Fabrication of organic emissive thin films by mist deposition method and evaluation of substrate temperature dependence
Mist deposition method has the advantage of low-cost and energy-saving for the fabrication of organic thin films. We fabricated thin films of organic emissive materials, tris (8-hydroxyquinoline) (Alq3) and rhodamine 6G by the mist deposition method using ultrasonic transducer. The thicknesses of them clearly depend on the substrate temperature during the mist deposition by the boiling point of the solvent. The PL spectra clearly demonstrated that the thin films of Alq3 and rhodamine 6G were successfully fabricated.
Heteroepitaxy of Corundum-Structured α-Ga2O3 Thin Films on α-Al2O3 Substrates by Ultrasonic Mist Chemical Vapor Deposition
Ga2O3 thin films of the α-phase, that is, the corundum structure (in the trigonal system), have been epitaxially obtained on sapphire (α-Al2O3) substrates, in contrast to the strong tendency of Ga2O3 to assume a heterogeneous crystal structure, that is, the β-gallia structure (in the monoclinic system) on sapphire. This result is advantageous for high-quality films and is due to the growth by mist chemical vapor deposition (CVD) at low temperatures of 430–470 °C. The α-Ga2O3 films have narrow full-widths at half maximum (FWHMs) in their X-ray diffraction rocking curves, for example, about 60 arcsec. The root mean square (RMS) roughness of the surface was as small as 1 nm. The optical band gap energy obtained was 5.3 eV, and the films were almost completely transparent in the near-ultraviolet and visible regions. The epitaxial growth of α-Ga2O3 films on sapphire is beneficial for the fabrication of oxide optical and electronic devices.
Physical Processes in Inorganic Scintillators
BASIC PRINCIPLES AND PROCESSES Physical Mechanism of Scintillation Creation of Electron Hole Pairs Excitation and Emission of Luminescence Centers Scintillation Materials Halides Oxides and Oxide Systems Chalcogenides Glasses Interaction of Ionizing Radiation with Scintillators High Energy Photons Charged Particles Neutral Particles General Characteristics of Inorganic Scintillators Light Yield Duration of Scintillation Pulse Afterglow Temperature Response Optical Properties Radiation Hardness Density Emission Spectra Mechanical and Chemical Properties Physical Parameters Cost Consideration Scintillator Requirements in Various Applications High Energy Physics Intermediate Energy Physics Positron Emission Tomography Gamma Spectroscopy Energy Resolution Intrinsic Scintillator Resolution Nonproportional Response Time Resolution Low Energy Quanta and Electrons CONVERSION OF ELECTRONIC EXCITATIONS IN SOLIDS Charge Carrier Behaviors Delta Rays Secondaries Excitation of Luminescence Centers Effect of Ionization Density Energy Losses Simple Phenomenological Model Plasmon Model Polaron Model Scintillation Yield Spectra Vacuum Ultraviolet Region Ultrasoft X-Rays X-Rays Gamma Rays Heavy Ionizing Particles INTRINSIC LUMINESCENCE OF INORGANIC SCINTILLATORS Excitonic Luminescence Alkali Halide Crystals Alkaline-Earth Fluorides Ternary Halide Compounds Excitonic-Like Luminescence Cesium Iodide Tungstate and Molybdate Phosphors Core-to-Valence Transitions First Evidence for Radiative Core-to-Valence Transitions Excitation Spectra Emission Spectra Experiment Theory Luminescence Kinetics Experimental Theoretical Investigations Temperature Dependence of Luminescence Parameters Conditions of Detection Prospects for Research EXTRINSIC LUMINESCENCE OF INORGANIC SCINTILLATORS Thallium-Activated Halide Scintillators Crystals with NaCl-Type Structure Crystals with CsCl-Type Structure Other Thallium-Based and Thallium-Doped Crystals Crystals Containing Other ns2 Ions Bismuth Germanate (BGO) Sodium-Activated Cesium Iodide Rare-Earth-Activated Crystals General Considerations Europium-Activated Crystals Cerium-Activated Compounds Preliminary Comments LaF3-CeF3 Systems Cerium Chloride Barium Fluoride Gadolinium-Containing Crystals Lu- and Y-Containing Crystals Nd- and Pr-Activated Crystals DEFECT FORMATION BY IONIZING RADIATION Effect on Scintillator Characteristics Mechanisms of Defect Formation Efficiency of Defect Production Geometrical Factor Separation between F and H Centers Temperature Dependence of Production Efficiency Role of Halogen Ion Impurities Effect of Cation Impurities Formation Time of F-H Pairs Closing Comments References Index