K.D. Vuong

CdS thin film deposition by CW Nd:YAG laser

Abstract We report cumulative results on CW Nd:YAG laser deposition of CdS thin films. Films are characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy, ultraviolet through visible light transmission, and Raman measurements. Films deposited at 400 °C or higher manifest a pure hexagonal CdS phase, and films deposited at 200 °C or lower contain both cubic and hexagonal phases.

FTIR investigation of RF plasma deposited indium-tin oxide films on glasses

Indium-tin oxide (ITO) thin films were coated on soda-lime silicate (SLS) and silica glasses by a newly developed an RF plasma mist deposition process. Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy was used to investigate the ITO films and interfaces between the films and the glasses. The infrared results indicated that the network structure near the glass-film interface is significantly modified by the indium and/or tin oxide coatings. During film deposition, depositing materials diffused into the glass substrates and created non-bridging oxygens near the surface of the glasses, which breaks down the network structure of the glasses. The glass structure was affected more significantly with a higher indium concentration. The deposited materials had stronger effects on the tin-side of SLS glass than on the air-side, at higher indium concentration.

Transparent-conductive indium tin oxide films fabricated by atmospheric r.f. plasma deposition technique

Abstract We report new results on indium tin oxide (ITO) films fabricated on a soda lime silicate (SLS) glass by an atmospheric r.f. plasma mist deposition process. The ITO films and powders were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and infrared spectroscopy. As-deposited films are uniform, transparent, and conductive. Phase formation, lattice parameters, and binding energies depend on the indium-to-tin ratio. When the tin concentration is low, the resultant phase is a cubic indium oxide. As the tin concentration increases from 0% to 40%, the cubic lattice parameter increases. When the indium concentration is low, the resultant phase is a tetragonal tin oxide. As the indium concentration increases from 0% to 20%, the tetragonal lattice parameters increase, while the tin binding energies decrease slightly.

Functional ITO coatings on glasses by RF plasma mist technique in ambient atmosphere

Abstract Recently, we developed an RF plasma mist deposition technique in ambient atmosphere. Indium tin oxide films have been coated on soda—lime—silicate and fused silica glass substrates, at deposition temperatures ranging from 400 to 750°C. As-deposited films are uniform and homogeneous as revealed by scanning electron microscopy, atomic force microscopy and energy dispersive spectroscopy, X-ray diffraction indicated that either indium oxide (In 2 O 3 ) or tin oxide (SnO 2 ) is formed depending on the indium-to-tin ratio (In:Sn). Average sizes of crystallites in the films are between 6 and 35 nm. Furthermore, as-deposited films are nearly 100% transparent in the visible range and the maximum conductivity occurs near In:Sn ratio of 9:1. Other material properties, such as the optical absorption edge and lattice parameters are also dependent on the In:Sn ratio.

Fabrication of cadmium sulfide thin films by CW Nd:YAG laser deposition

We report new results on continuous wave Nd:YAG laser deposition of Cadmium Sulfide (CdS) thin films. Cadmium Sulfide has useful piezoelectric, optoelectric, photo-conductive and semiconductive properties. CdS films have been deposited on various substrates including Soda-lime silicate glass (SLS), NaCl, Alumina (corundum) and copper coated formvar. The thin films were analyzed using x-ray diffraction, SEM, EDS, TEM, and UV/visible transmission spectra.

CdS thin films prepared by continuous wave Nd:YAG laser

We report new results on continuous wave Nd:YAG laser deposition of cadmium sulfide thin films. Substrates were soda-lime silicate glass, silica glass, silicon, and copper coated formvar sheets. As deposited films were mixtures of cubic and hexagonal phases, with two different grain sizes. As revealed by SEM micrographs, films had smooth surface morphology. As revealed by TEM analysis, grain sizes were extremely small.

Atmospheric rf plasma coating of indium and tin oxide films

Indium tin oxide (ITO) thin films on soda-lime-silicate (SLS) and silica glasses were fabricated using an rf plasma mist deposition process. SEM analysis showed that the ITO films consisted of uniform particle size with a size ranging from 50 to 200 nm. XRD revealed that In2O3 phase is present in the film when In:Sn ratio is 5:5 and higher. The resistivity of the ITO films was between 1 - 10 ohm-cm. The structural change near the surface of the glass was investigated by DRIFT (diffuse reflectance infrared Fourier transform) spectroscopy. The infrared results indicated that the structure near the surface was significantly changed with higher indium concentration. The coating materials create non-bridging oxygen near the surfaces. The effects of deposition time and substrate temperature were also studied.

Fabrication of CDS Thin Films Using Continuous Wave Laser Evaporation

The authors report new results on continuous wave Nd:YAG laser deposition of Cadmium Sulfide (CdS) thin films. Substrates were soda-lime silicate (SLS) glass, silica glass, silicon, alumina, and copper coated formvar sheets. As-deposited films were characteristically mixtures of cubic and hexagonal phases. X-ray diffraction analysis reveals that two different grain size groups are present. As revealed by SEM micrographs, films had smooth surface morphology. Transmission electron microscopy analysis reveals that grain sizes were extremely small. Also, semiconductive behavior was noted.

Effect of Y/sub 2/BaCuO/sub 5/ and PtO/sub 2//spl middot/H/sub 2/O additions on the microstructural development in YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// superconductors

Results are presented concerning the formation kinetics of Y/sub 2/BaCuO/sub 5/ (211) and YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (123) phases during melt processing of melt quench (MQ) precursors and phase pure 123. The influence of Pt and 211 additions on microstructural development within YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// system are examined quantitatively via XRD analysis and DTA. Real time dynamic XRD analysis showed the phase reaction sequences for the MQ and phase pure 123 (SSC) precursor systems, and revealed the activation energy (E/sub a/) for 211 formation to be lower for MQ powders upon peritectic decomposition. The SSC precursors developed greater amounts of 211 at 1100/spl deg/C when compared to MQ precursors, (/spl sim/28 wgt% vs. 10 wgt% respectively). The addition of 0.5 m/o 211 additions in SSC resulted in lower 123 temperatures and E/sub a/ than that without 211 addition. Pt additions did alter the residual 211 content upon texturing. The presence of Pt with excess 211 additions was seen to inhibit 211 formation upon texturing.<<ETX>>

Examination of Y2Cu2O5 additions on microstructural development in YBa2Cu3O7 − δ superconductors

The role of Y2Cu2O5 on liquid phase flux and microstructure evolution were examined in two series of experiments. The first series of experiments dealt with a low temperature processing ( 1020 dgC) melt powder melt growth process (MPMG). Differential thermal analysis measurements were used to study the impact on liquidus formation reactions, solidification temperatures and kinetics. Microstructural evaluations via SEM, EDS along with TEM and microdiffraction techniques reveal some unique aspects of Y2Cu2O5 additions on the liquid phase matrix and microstructural refinement during processing. The yttrium enrichment of the Pt-Ba-Cu-O phase for MPMG samples was shown along with significant coalescence of such a phase not seen in similar samples with Y2Cu2O5. Extensive liquidus formation occurs allowing for texturing via diffusive couple oxide liquid phase intrusion below the peritecticecomposition.