Influence of Annealing Temperature on Structure, Optical Loss and Laser-Induced Damage Threshold of TiO2 Thin Films

TiO2 thin films are prepared on fused silica with conventional electron beam evaporation deposition. After annealed at different temperatures for 4h, the spectra and XRD patterns of the TiO2 thin film are obtained. Weak absorption of coatings is measured by the surface thermal lensing technique, and laser-induced damage threshold （LIDT） is determined. It is found that with the increasing annealing temperature, the transmittance of TiO2 films decreases. Especially when coatings are annealed at high temperature over 1173K, the optical loss is very serious. Weak absorption detection indicates that the absorption of coatings decreases firstly and then increases, and the absorption and defects play major roles in the LIDT of TiO2 thin films.     

Preparation and Properties of GaN Films on GaAs Substrates

Polycrystalline gallium nitride films with hexagonal structure were prepared by a post-nitridation technique. A strong blue photoluminescence located at 458 nm and a UV photoluminescence located at 368 nm were observed at room temperature. The 368 nm peak is PL from band-edge emission. The blue luminescence is attributed to the transition from deep donor level to the valence band.     

Effect of Alumina and Chromium Interlayers on Microstructures and Optical Properties of Thin Ag Films on Glass Substrates

Effects of alumina and chromium interlayers on the microstructure and optical properties of thin Ag films are investigated by using spectrophotometry, x-ray diffraction and AFM. The characteristics of Ag films in Ag/glass, Ag/l2O3/glass and Ag/Cr/glass stacks are analysed. The results indicate that the insertion of an Al2O3 or Cr layer decreases the grains and influences the reflectance of Ag films. The reflectance of the Ag film can be increased by controlling the thickness of alumina interlayer. The stability of Ag films is improved and the adhesion of Ag films on glass substrates is enhanced by alumina as an interlayer.     

Structure and Optical Characteristics of Barium–Strontium Niobate Films on Al2O3 Substrates

Optics and Spectroscopy - The structure and optical characteristics of thin films of relaxor ferroelectric Ba0.5Sr0.5Nb2O6 grown by RF sputtering in an oxygen atmosphere on an Al2O3 substrate (c...     

Influences of Annealing on Residual Stress and Structure of HfO2 Films

HfO2 films are deposited on BK7 glass substrates by electron beam evaporation. The influences of annealing between 100℃ and 400℃ on residual stresses and structures of HfO2 films are studied. It is found that little differences of spectra, residual stresses and structures are obtained after annealing at lower temperatures. After annealing at higher temperatures, the spectra shift to short wavelength, the residual stress increases with the increasing annealing temperature. At the same time, the crystallite size increases and interplanar distance decreases. The variations of optical spectra and residual stress correspond to the evolutions of structures induced by annealing.     

Influence of Thermal Treatment on the Thermal Behavior of Poly‐L‐lactide

The influences of thermal treatment on cold crystallization and the thermal behavior of poly‐L‐lactide (PLLA) were investigated by DSC and polarizing microscopy. Both the cooling and heating rates had effects on cold crystallization. Double peaks were observed for the samples on subsequently heating at 10°C min^?1 after cooling between 5 and 20°C min^?1. The degrees of crystallinity dramatically increased with decreasing cooling rate, and the size of PLLA spherulites increased with a decrease in the cooling rate. Double cold crystallization peaks were also observed during heating traces at higher rates for this material after fast cooling (20°C min^?1) from the melt. The competition between the crystallization from the nuclei formed during cooling, and that from spontaneous nucleation might be responsible for the appearance of double peaks.     

Highly c-Oriented Nanocolumn Structure ZnO Films on Sapphire Substrates by Pulsed Laser Deposition

Highly c-oriented nanocolumn structure ZnO films were successfully deposited on sapphire (0001) substrates by pulsed laser deposition at a substrate temperature of 500℃ and 200mTorr oxygen pressure. X-ray diffraction, scanning electron microscopy, photoluminescence, and spectroscopic ellipsometry were used to characterize the     

Influence of LiB3O5 Structure on Microstructure and Optical Properties of ZrO2 Thin Films Prepared by Electron Beam Evaporation

ZrO2 thin films were deposited by using an electron beam evaporation technique on three kinds of lithium triborate (LIB3O5 or LBO) substrates with the surfaces at specified crystalline orientations. The influences of the LBO structure on the structural and optical properties of ZrO2 thin films are studied by spectrophotometer and x-ray diffraction. The results indicate that the substrate structure has obvious effects on the structural and optical properties of the film: namely, the ZrO2 thin film deposited on the X-LBO, Y-LBO and Z-LBO orients to m(-212), rn(021) and o(130) directions. It is also found that the ZrO2 thin film with m(021) has the highest refractive index and the least lattice misfit.     

Effect of Annealing on Optical Properties of InAs Quantum Dots Grown by MOCVD on GaAs （100） Vicinal Substrates

Thermal annealing effect on lnAs quantum dots grown on vicinal （100） GaAs substrates is studied in comparison with dots on exact （100） GaAs substrates. We find that annealing acts stronger effect on dots with vicinal substrates by greatly accelerating the degradation of material quality, as well as slightly increasing the blueshift of the emission wavelength and the narrowing of PL linewidth. It is attributed to the higher strain in the dots formed on the vicinal substrates.     

Structure Stability of LaAlO3 Thin Films on Si Substrates

A series of amorphous and single-crystalline LaAlO3 （LAO） thin films are fabricated by laser molecular-beam epitaxy technique on Si substrates under various conditions of deposition. The structure stability of the LAO films annealed in high temperature and various ambients is studied by x-ray diffraction as well as high-resolution transmission electron microscopy. The results show that the epitaxial LAO films have very good stability, and the structures of amorphous LAO thin films depend strongly on the conditions of deposition and post-annealing. The results reveal that the formation of LAO composition during the deposition is very important for the structure stability of LAO thin films.     

Synthesis and Optical Properties of Films Formed by the Sol‐Gel Method in Mesoporous Matrices

The main laws governing the formation of films by the solgel method in the mesopores of anodic aluminum oxide, porous silicon, and synthetic opals have been considered. Investigations of the luminescence at 1.5 m in the structure porous silicon–gel, doped with erbium, have been analyzed. Special features of the synthesis of the film structure microporous xerogel–mesoporous anodic aluminum oxide, doped with erbium, terbium, and europium, and the possible factors that enhance the photoluminescence of lanthanides in the structure are shown.     

Effect of Ag Doping on Optical and Electrical Properties of ZnO Thin Films

ZnO thin films were prepared on p-type Si (100) substrates by the sol-gel process. The influence of Ag doping at a content of 0.002% on the photoluminescence and current-voltage (I - V) characteristics of ZnO thin films has been investigated. It is found that Ag doping leads to a pronounced increase in the intensity of near band edge emission at 3.23eV and a remarkable red shift of the visible broadband at room temperature. The I - V characteristics of ZnO/p-Si heterojunctions are also changed. These results could be explained by Ag substituting for Zn in Ag doped ZnO thin films.     

The Influence of Polyvinylpyrrolidone on the Structure and Optical Properties of ZnO–MgO Nanocomposites Synthesized by the Polymer–Salt Method

Optics and Spectroscopy - The influence of polyvinylpyrrolidone on the structure and optical properties of ZnO–MgO nanocomposites synthesized by the polymer–salt method is studied. The...     

In-Plane Thermal Diffusivity Measurement of Thin Films Based on the Alternating-Current Calorimetric Method Using an Optical Reflectivity Technique

An advanced ac calorimetric method to measure thermal diffusivity of a thin sample is developed by using an optical reflectivity technique. A modulated infrared laser is used to heat the front surface of a foil specimen. The reflectivity of a continuous-wave He-Ne laser at the rear surface of the specimen is detected by a photoreceiver.     

The Effects of Annealing on the Surface Properties of Titania Films Prepared on Titanium by Micro-Arc Oxidation

Titanium and its alloys are widely used in the aerospace, marine, and biomedical industry due to their unique bulk properties such as high strength-to-weight ratio and melting temperature, good corrosion resistance, and favorable biocom- patibility. However, in some applications, com- ponents made of titanium or titanium alloys exhibit poor wear resistance under stationary or dynamic loading as well as contact corrosion manifested by the relatively negative standard electrode potential （-1.63 V ） . In order to improve the surface properties of titanium and its alloys, several techniques such as PVD （ physical vapor deposition ） /CVD （chemical vapor deposition ） coatings,     

Relationship of Processing Conditions to Structure and Properties in PMDA‐ODA Polyimide

A combined wide angle X‐ray diffraction (WAXD)/small‐angle X‐ray scattering (SAXS)/scanning electron microscopy (SEM)/density study of structure and morphology was carried out for a large series of pyromellitic dianhydride‐oxydianiline (PMDA‐ODA) polyimide (PI) samples processed using different powder metallurgy techniques. Using a combined DSC/creep rate spectroscopy (CRS)/long‐term creep resistance (LTCR) approach, their molecular dynamics, thermal and elastic properties, and creep resistance in the temperature range from 20 to 470°C were also studied. Both a choice of the method of formation of fine PI particles and the order of applying high pressure relative to high temperature to form the monolithic samples led to the observation of significant property differences. Relationships between the processing conditions, structure, and properties were determined. As a result, the conditions for optimizing certain PMDA‐ODA polyimide properties, especially creep resistance and elastic properties at extreme temperatures, were determined.     

Structural and Optical Properties of Zinc Nitride Films Prepared by Pulsed Filtered Cathodic Vacuum Arc Deposition

Polycrystalline zinc nitride films are deposited on Coming 7059 glass substrates by pulsed filtered cathodic vacuum arc deposition （PFCVAD）. The crystallographic structure is studied by means of x-ray diffraction. These measurements show that all the films are crystallized in the cubic structure, in a preferred orientation along the （332） and （631） directions. Weak XRD signal shows small crystallites distributed in an amorphous tissue. A small improvement of crystallinity is observed with annealing. Optical parameters such as absorption, energy band gap, Urbach tail, extinction coefficients have been determined. The Urbach tail energy is decreased with annealing at 500℃ for one hour. Energy band gap values are found to be increased by annealing.     

Effect of Pretreatment of TaN Substrates on Atomic Layer Deposition Growth of Ru Thin Films

The polycrystalline ruthenium films are grown on TaN substrates by atomic layer deposition （ALD） using bis（cyclopentadienyl） ruthenium [RuCp2] and oxygen as ruthenium precursor and reactant respectively at a deposition temperature of 330℃. The low-energy Ar ion bombardment and Ru pre-deposition are performed to the underlying TaN substrates before ALD process in order to improve the Ru nucleation. X-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy are carried out to characterize the properties of ALD Ru films. The results show that the nucleation density of Ru films with Ar^＋ bombardment to the underlying TaN substrates is much higher than that of the ones without any pretreatment. The possible reasons are discussed.