Deposition of Thin Titania Films by Dielectric Barrier Discharge at Atmospheric Pressure

A homogeneous atmospheric pressure dielectric barrier discharge is studied. It is in argon with small admixtures of titanium tetrachloride vapour and oxygen for the deposition of thin titania films on glass substrates. A special electrode configuration was applied in order to deposit the titania film uniformly. The sustaining voltage （6 kV to 12 kV）, current density （about 3 mA/cm^2） and total optical emission spectroscopy were monitored to characterize the discharge in the gap of 2 mm. Typical deposition rates ranged from approximately 30 nm/min to 120 nm/min. The film morphology was investigated by using scanning electron microscopy （SEM） and the composition was determined with an energy dispersive x-ray spectroscopy （EDS） analysis tool attached to the SEM. The crystal structure and phase composition of the films were studied by x-ray diffraction （XRD）. Several parameters such as the discharge power, the ratio of carrier gas to the precursor gas, the deposition time on the crystallization behavior, the deposition rate and the surface morphology of the titania film were extensively studied.

Principle and Process Window of Cerium Dioxide Thin Film Fabrication with Dual Plasma Deposition

Cerium dioxide, CeO2, is a potentially superior material in a myriad of areas, and many methods have been proposed to deposit single crystal CeO2 thin films. A novel fabrication technique utilizing dual plasma generated by metal vacuum arc (MEVVA) and radio frequency (RF) is discussed in this paper. We have recently conducted a systematic investigation to determine the optimal process window to deposit CeO2 thin films'on Si(100) substrates. The X-ray diffraction results show the existence of CeO2(100) in the as-deposited sample.

Deposition Methods and Properties of Polycrystalline CdS Thin Films

CdS thin film was used as a suitable window layer for CdS/Cd Te solar cell, and the properties of CdS thin films deposited by pulsed laser deposition（PLD）, chemical bath deposition（CBD） and magnetron sputtering（MS） were reported. The experimental results show that the transmittances of PLD-Cd S thin films are about 85% and the band gaps are about 2.38-2.42 e V. SEM results show that the surface of PLD-Cd S thin film is much more compact and uniform. PLD is more suitable to prepare the Cd S thin films than CBD and MS. Based on the thorough study, by using totally PLD technique, the FTO/PLD-Cd S（150 nm）/CSS-Cd Te solar cell（0.0707 cm^2） can be prepared with an efficiency of 10.475%.

Carbon Nitride Films Deposited on Pt Substrates byMicrowave Plasma Chemical Vapor Deposition

Carbon nitride thin films have been synthesized on polycrystalline Pt substrates using microwave plasma chemical vapor de- position (MPCVD) technique. The N/C atomic ratio is close to the stoichiometric value 1.33 of C_3N_4. The experimental X-ray diffraction spectra contain all the strong peaks of α-C_3N_4 and β -C_3N_4. The films are a mixture of α-C_3N_4 and β -C_3N_4. The observed Raman and FT- IR spectra support the existence of C-N covalent bond in carbon nitride compound. The bulk modulus detected by Nano II nanoindentor is up to 349 GPa.

Cubic AlN thin film formation on quartz substrate by pulse laser deposition

Cubic AlN thin films were obtained on quartz substrate by pulse laser deposition in a nitrogen reactive atmosphere.A Nd-YAG laser with a wavelength of 1064 nm was used as the laser source.In order to study the influence of the process parameters on the deposited AlN film,the experiments were performed at various technique parameters of laser energy density from 70 to 260 J/cm^2,substrate temperature from room temperature to 800℃and nitrogen pressure from 0.1 to 50 Pa.X-ray diffraction,scanning electron microscopy and X-ray photoelectron spectroscopy were applied to characterize the structure and surface morphology of the deposited AlN films.It was found that the structure of AlN films deposited in a vacuum is rocksalt under the condition of substrate temperature600-800 ℃,nitrogen pressure 10-0.1 Pa and a moderate laser energy density（190 J/cm^2）.The high quality AlN film exhibited good optical property.

Review of recent progresses on flexible oxide semiconductor thin film transistors based on atomic layer deposition processes

The current article is a review of recent progress and major trends in the field of flexible oxide thin film transistors（TFTs）, fabricating with atomic layer deposition（ALD） processes. The ALD process offers accurate controlling of film thickness and composition as well as ability of achieving excellent uniformity over large areas at relatively low temperatures. First, an introduction is provided on what is the definition of ALD, the difference among other vacuum deposition techniques, and the brief key factors of ALD on flexible devices. Second, considering functional layers in flexible oxide TFT, the ALD process on polymer substrates may improve device performances such as mobility and stability, adopting as buffer layers over the polymer substrate, gate insulators, and active layers. Third, this review consists of the evaluation methods of flexible oxide TFTs under various mechanical stress conditions. The bending radius and repetition cycles are mostly considering for conventional flexible devices. It summarizes how the device has been degraded/changed under various stress types（directions）. The last part of this review suggests a potential of each ALD film, including the releasing stress, the optimization of TFT structure, and the enhancement of device performance. Thus, the functional ALD layers in flexible oxide TFTs offer great possibilities regarding anti-mechanical stress films, along with flexible display and information storage application fields.

Progress in flexible perovskite solar cells with improved efficiency

Perovskite solar cell has emerged as a promising candidate in flexible electronics due to its high mechanical flexibility,excellent optoelectronic properties,light weight and low cost.With the rapid development of the device structure and materials processing,the flexible perovskite solar cells(FPSCs)deliver 21.1%power conversion efficiency.This review introduces the latest developments in the efficiency and stability of FPSCs,including flexible substrates,carrier transport layers,perovskite films and electrodes.Some suggestions on how to further improve the efficiency,environmental and mechanical stability of FPSCs are provided.Specifically,we considered that to elevate the performance of FPSCs,it is crucial to substantially improve film quality of each functional layer,develop more boost encapsulation approach and explore flexible transparent electrodes with high conductivity,transmittance,low cost and expandable processability.

Analysis of angular-selective performances of obliquely deposited birefringent thin film

A slanted columnar TiO2 sculptured anisotropic thin film is prepared using the glancing angle deposition(GLAD) technique. We extend the inference regarding the optical properties of a uniaxial birefringent film based on theoretical analysis to include the more general case of a multilayer biaxial birefringent thin film, the optic axis of which is in the incident plane. We also investigate in detail the symmetrical angularselective transmittance performances of TiO2 biaxial anisotropic thin films for light incident at the same angle but coming from opposite sides of the surface normal. The tilted nanocolumn microstructures of the birefringent thin films induce optical anisotropy. The transmisson spectra for the p-polarized wave of TiO2 biaxial anisotropic thin film measured in the experiment almost overlap at the symmetrical oblique incidence at the ±θ 0 angles, which validates our theoretical derivation.