Ti Doped Cu2O Thin Films: DC Magnetron Sputtering and Structural and Optical Studies

Ti doped Cu2O thin films were prepared at distinct Argon/Oxygen gas flow ratio of 34/1, 33/2,32/3 and 31/4 with net flow (Ar+O2) of 35 sccm by using DC magnetron sputtering system on glass substrates at room temperature. The gas mixture influence on the film properties studied by using X-ray diffraction, Field emission scanning electron microscopy and UV-Visible spectroscopy. From XRD results, it is evident that, with a decrease in oxygen content, the amplitude of (111) peak increased, peak at a 35.67o scattering angle and the films shows a simple cubic structure. The FESEM images indicated the granularity of thin films was distributed uniformly in a homogenous model and also includes especially pores and cracks. The film deposited at 31/4 showed a 98% higher transmittance in the visible region.

Defect Passivation and Carrier Reduction Mechanisms in Hydrogen-Doped In-Ga-Zn-O (IGZO:H) Films upon Low-Temperature Annealing for Flexible Device Applications

Low-temperature activation of oxide semiconductor materials such as In-Ga-Zn-O (IGZO) is a key approach for their utilization in flexible devices. We previously reported that the activation temperature can be reduced to 150 °C by hydrogen-doped IGZO (IGZO:H), demonstrating a strong potential of this approach. In this paper, we investigated the mechanism for reducing the activation temperature of the IGZO:H films. In situ Hall measurements revealed that oxygen diffusion from annealing ambient into the conventional Ar/O2-sputtered IGZO film was observed at >240 °C. Moreover, the temperature at which the oxygen diffusion starts into the film significantly decreased to 100 °C for the IGZO:H film deposited at hydrogen gas flow ratio (R[H2]) of 8%. Hard X-ray photoelectron spectroscopy indicated that the near Fermi level (EF) defects in the IGZO:H film after the 150 °C annealing decreased in comparison to that in the conventional IGZO film after 300 °C annealing. The oxygen diffusion into the film during annealing plays an important role for reducing oxygen vacancies and subgap states especially for near EF. X-ray reflectometry analysis revealed that the film density of the IGZO:H decreased with an increase in R[H2] which would be the possible cause for facilitating the O diffusion at low temperature.

Plasma polishing processes applied on optical materials: A review

Nowadays, the surface quality of the material is crucial for industry and science. With the development of micro-electronics and optics, the demand for surface quality has become more and more rigorous, making optical surface polishing more and more critical. Plasma polishing technology is conceived as an essential tool for removing surface and subsurface damages from traditional polishing processes. The plasma processing technology is based on plasma chemical reactions and removes atomic-level materials. Plasma polishing can easily nano-finish hard-brittle materials such as ceramics, glass, crystal, fused silica, quartz, Safire, etc. The optical substrate with micro-level and nano-level surface roughness precision is in demand with the advancement in optics fabrication. The mechanical properties of super-finished optics materials are being used to fulfill the requirement of modern optics. This article discusses the processing of different types of freeform, complex and aspheric optical materials by the plasma polishing process used mainly by the optical industry. The plasma polishing devices developed in the last decade are thoroughly reviewed for their working principles, characteristics and applications. This article also examines the impact of various process parameters such as discharge power, rate of gas flow, mixed gas flow ratio and pressure on the plasma polishing process.

Effects of the Nitrogen Flow Ratio and Substrate Bias on the Mechanical Properties of W–N and W–Si–N Films

The reactive gas flow ratio and substrate bias voltage are crucial sputtering parameters for fabricating transition metal nitride films. In this study, W–N films were prepared using sputtering with nitrogen flow ratios (f) of 0.1–0.5. W–N and W–Si–N films were then prepared using an f level of 0.4 and substrate bias varying from 0 to −150 V by using sputtering and co-sputtering, respectively. The variations in phase structures, bonding characteristics, mechanical properties, and wear resistance of the W–N and W–Si–N films were investigated. The W–N films prepared with nitrogen flow ratios of 0.1–0.2, 0.3, and 0.4–0.5 displayed crystalline W, amorphous W–N, and crystalline W2N, respectively. The W–N films prepared using a nitrogen flow ratio of 0.4 and substrate bias voltages of −50 and −100 V exhibited favorable mechanical properties and high wear resistance. The mechanical properties of the amorphous W–Si–N films were not related to the magnitude of the substrate bias.

Preparation of Copper Nitride Films with Superior Photocatalytic Activity through Magnetron Sputtering

TiO2 possesses a wide forbidden band of about 3.2 eV, which severely limits its visible light absorption efficiency. In this work, copper nitride (Cu3N) films were prepared by magnetron sputtering at different gas flow ratios. The structure of the films was tested by scanning electron microscope, X-ray diffractometer, and X-ray photoelectron spectroscope. Optical properties were investigated by UV-vis spectrophotometer and fluorescence spectrometer. Results show that the Cu3N crystal possesses a typical anti-ReO3 crystal structure, and the ratio of nitrogen and Cu atoms of the Cu3N films was adjusted by changing the gas flow ratio. The Cu3N films possess an optical band gap of about 2.0 eV and energy gap of about 2.5 eV and exhibit excellent photocatalytic activity for degrading methyl orange (degradation ratio of 99.5% in 30 min). The photocatalytic activity of Cu3N mainly originates from vacancies in the crystal and Cu self-doping. This work provides a route to broaden the forbidden band width of photocatalytic materials and increase their photoresponse range.

Performance of a cyclone scrubber on removal of fine particulate matter

Cyclones are not classified as effective devices for removing fine particles, while high efficiency wet scrubbers usually have high operational costs. In order to achieve better performance, the aim of this study is to evaluate, for the first time, a cyclone scrubber design based on the dimensions of a Stairmand cyclone separator with the inclusion of liquid injection nozzles located in different positions to improve the separation of fine particles. Given the lack of studies considering the effect of liquid injection and other operational conditions in the removal performance of a cyclone scrubber with Stairmand dimensions, the present paper provides a complete evaluation of these effects for the separation of sugar cane bagasse ash from air. The parameters investigated were inlet gas velocity, liquid injection position, liquid-to-gas flow ratio and droplet size distribution. The cyclone scrubber performance was evaluated considering collection efficiency and pressure drop. Overall efficiency of almost 99% and low-pressure drop was achieved by employing a liquid-to-gas flow ratio of 0.43 L/m? for the collection of ash from the combustion of sugar cane bagasse. Grade efficiencies revealed that injecting droplets into cyclones significantly improved the removal of fine particles with an aerodynamic diameter less than 2.5 ?m.

Influence of N2 Gas Flow Ratio and Working Pressure on Amorphous Mo–Si–N Coating during Magnetron Sputtering

In this study, Mo–Si–N coatings were deposited on Si wafers and tungsten carbide substrates using a reactive direct current magnetron sputtering system with a MoSi powder target. The influence of sputtering parameters, such as the N2 gas flow ratio and working pressure, on the microstructure and mechanical properties (hardness (H), elastic modulus (E), and H/E ratio) of the Mo–Si–N coatings was systematically investigated using X-ray diffractometry (XRD), scanning electron microscopy (SEM), nanoindentation, and transmission electron microscopy (TEM). The gas flow rate was a significant parameter for determining the crystallinity and microstructure of the coatings. A Mo2N crystalline coating could be obtained by a high N2 gas flow ratio of more than 35% in the gas mixture, whereas an amorphous coating could be formed by a low N2 gas flow ratio of less than 25%. Furthermore, the working pressure played an important role in controlling the smooth surface and densified structure of the Mo–Si–N coating. For the amorphous Mo–Si–N coating deposited with the lowest working pressure (1 mTorr), the hardness, elastic modulus, and H/E ratio reached from 9.9 GPa, 158.8 GPa, and 0.062 up to 17.9 GPa, 216.1 GPa, and 0.083, respectively.

Plasma Etching of SiO2 with CF3I Gas in Plasma-Enhanced Chemical Vapor Deposition Chamber for In-Situ Cleaning

Non-global-warming CF3I gas has been investigated as a removal etchant for SiO2 film. Thermally fabricated SiO2 films were etched by the plasma generated with a gas mixture of CF3I and O2 (CF3I/O2) in the plasma-enhanced chemical vapor deposition chamber. The etch rate of SiO2 films was studied along with the process parameters of plasma etching such as chamber pressure, etching gas flow ratio of CF3I to CF3I/O2, plasma power, and chamber temperature. Increasing the chamber pressure from 400 to 1,000 mTorr decreased the etch rate of SiO2 film. The etch rate of this film showed a minimum value at a gas flow ratio of 0.71 in CF3I to CF3I/O2 and then increased at a higher CF3I gas flow ratio. In addition, the elevated plasma power increased the etch rate. However, the chamber temperature has little effect on the etch rate of SiO2 films. When only CF3I gas without O2 was supplied for etching, polymerized fluorocarbon was formed on the surface, indicating the role of oxygen in ashing the polymerized fluorocarbon during the etching process.

Effect of Differentiated Injection Ratio, Gas Flow Rate, and Slag Thickness on Mixing Time and Open Eye Area in Gas-Stirred Ladle Assisted by Physical Modeling

In this work, the effects of equal (50%/50%) or differentiated (75%/25%) gas flow ratio, gas flow rate, and slag thickness on mixing time and open eye area were studied in a physical model of a gas stirred ladle with dual plugs separated by an angle of 180°. The effect of the variables under study was determined using a two-level factorial design. Particle image velocimetry (PIV) was used to establish, through the analysis of the flow patterns and turbulence kinetic energy contours, the effect of the studied variables on the hydrodynamics of the system. Results revealed that differentiated injection ratio significantly changes the flow structure and greatly influences the behavior of the system regarding mixing time and open eye area. The Pareto front of the optimized results on both mixing time and open eye area was obtained through a multi-objective optimization using a genetic algorithm (NSGA-II). The results are conclusive in that the ladle must be operated using differentiated flow ratio for optimal performance.