X.W. Wang

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.

CW Nd:YAG Laser Deposition of CdS Thin Films

There are two phases of CdS, wurtzite (hexagonal) and zincblende (cubic). To the best of our knowledge there is no report on the growth of large single crystal cubic CdS. Although there have been reports on the vapor deposition of cubic dominated CdS thin films, physical measurements were limited. Substrate material has been considered as the primary factor in attaining the cubic dominated CdS thin films. We report new results on CW Nd:YAG laser deposition of CdS thin films at various temperatures. X-ray diffraction patterns show that the films deposited at 200°C have a dominant cubic phase, those at 400°C being hexagonal. Optical transmission measurements reveal room temperature absorption edges of 515nm and 500nm for films deposited at 200°C and 400°C, respectively. Transmission electron microscopy further reveals differences in crystal structure of the two films. Raman spectra of the cubic film is similar to that of the hexagonal film.

Crystalline and Electrical Properties of ITO Semiconductive Films deposited by Atmospheric RF Plasma Technique

Indium tin oxide (ITO) semiconductive films were deposited by an atmospheric RF plasma technique. Indium-to-tin (In:Sn) ratios varied from 10:0 to 0:10. A small amount of antimony was doped into some ITO samples for comparative studies. Substrate materials were soda-lime-silicate (SLS) float glass and fused silica glass. Structural, electrical, and optical properties were dependent on the In:Sn ratio, precursor material feeding rate, oxygen feeding rate, and other deposition conditions.

Cadmium Sulfide Films Deposited by Cw Laser Evaporation Technique

Cadmium Sulfide (CdS) thin films had been fabricated by a laser deposition technique. Our previous results indicated that the hexagonal structured films could be formed at a substrate temperature of 400 C or higher. Reducing the temperature to 200 C or lower, cubic dominant films had been fabricated. To further understand the effects of other deposition parameters, CdS films were deposited at 30 C in this study. Crystal structures of the films were analyzed by Xray diffraction (XRD) and Transmission Electron Microscopy (TEM). It was found that the processing windows for the cubic films were very limited. As revealed by optical transmission measurements, the optical absorption edge of the cubic film was different from that of the hexagonal film.