Chemical Vapor Deposition最新文献

This paper presents, for the first time, the synthesis, via aerosol-assisted (AA)CVD followed by annealing at 620 °C for 5 h, of pure Fe₂TiO₅ thin films on glass. The thin film is deposited from a one pot solution containing titanium isopropoxide and tris(acetylacetonato)iron in an ethyl acetate solvent. The film is characterized using a range of techniques including powder X-ray diffraction(XRD), wavelength dispersive X-ray (WDX) spectroscopy, X-ray photoelectron spectroscopy(XPS), scanning electron microscopy (SEM), and UV-vis spectroscopy. The photocatalytic activity of the film under UVA and visible light irradiation is also tested. The results show that Fe₂TiO₅ is able to degrade resazurin redox dye under UVA illumination at a rate much higher than Pilkington NSG Activ^TM, with a formal quantum efficiency (FQE) an order of magnitude superior.

This manuscript reports on the synthesis of copolymer films of glycidyl methacrylate with diethylaminoethyl methacrylate by initiated (i)CVD. The purpose of the incorporation of tertiary amine functionality in the copolymer film is to accelerate the rate of the nucleophilic ring-opening reaction of the epoxide group under benign conditions. It is found that tertiary amine functionality in the poly(glycidyl methacrylate) (PGMA) film significantly increases the rate and degree of the ring-opening reactions. After 2 h of reaction at room temperature, 72% of the epoxy groups are consumed, while the conversion under similar conditions is negligible for the PGMA film.

We developed aluminium phosphate-coated alumina fibres with significantly improved pull-out properties, which may be suitable for reinforcing advanced inorganic composites qualified for operating temperatures up to 1200 °C. Aluminium phosphate layers are generated on the surface of alumina fibres using a continuous chemical vapour deposition (CVD) process: At furnace temperatures between 850 °C and 1050 °C, within a tube reactor heated by an electrical furnace, the alumina fibres are exposed to gas mixtures of phosphoryl trichloride and oxygen, inducing dense aluminium phosphate layers on the fibre surface. Mini-composites were prepared by embedding the coated fibres into an alumina matrix.

Atomic layer deposition (ALD) is a thin film growth technique based on the repeated use of separate, saturating gas-solid reactions. The principle of ALD has been discovered twice; in the 1960s under the name “molecular layering” in the Soviet Union, and in the 1970s under the name “atomic layer epitaxy” (ALE) in Finland. In 2014, it is forty years since the filing of the worldwide patent on ALE as a method for the growth of compound thin films. This essay celebrates the fortieth anniversary of ALE-ALD, briefly telling the story of ALE as shared by its Finnish inventor, Dr. Tuomo Suntola. Initially, ALE was aimed at the growth of high-quality polycrystalline ZnS thin films for electroluminescent (EL) display panels. Gradually, the material selection of ALE increased, and the application areas were extended to photovoltaics, catalysis, semiconductor devices, and beyond. Fast, production-worthy ALE reactors were imperative for industrial success. The unprejudiced creation of new technologies and products with ALE, initiated by Dr. Tuomo Suntola and led by him until early 1998, are an integral part of the Finnish industrial history, the fruits of which are seen today in numerous applications worldwide.

The conventional atomic layer deposition (ALD) technologies are capable of fabricating supreme quality thin films of a wide variety of materials, but sequential introduction and purging of precursors and inert gases prevent its application in the mass production of thin films under atmospheric conditions. In this study, we introduce a novel technique of roll-to-roll atmospheric (R2R-A)ALD using a multiple-slit gas source head. Thin films of Al₂O₃ are developed on a movable web of polyethylene terephthalate (PET) substrate at 50 °C. The Al₂O₃ deposition is carried out under a working pressure of 740 Torr, which is very near to atmospheric pressure (760 Torr). An appreciable growth rate of 0.98 Å per cycle is observed at a carefully optimized web velocity of 7 mm s⁻¹. Good morphological, chemical, electrical, and optical characteristics are shown by the Al₂O₃ films produced at a large scale. Low root mean square roughness (R_q) values of 1.85 nm and 1.75 nm are recorded for the Al₂O₃ films deposited at 50 °C over 75 and 125 ALD cycles, respectively. The appearance of Al 2p, Al 2s, and O 1s peaks at the binding energies of 74 eV, 119 eV, and 531 eV, respectively, in the X-ray photoelectron spectroscopy (XPS) analysis confirms the fabrication of Al₂O₃ films, which is also supported by Fourier transform infrared spectroscopy (FTIR). The films show excellent insulating properties, and optical transmittance of more than 85% is recorded in the visible region.

The potential of an additional degree of freedom (DOF) in the effort to meet film or deposition rate uniformity along the wafer in CVD processes is investigated. The investigation applies to cases of deposition on a wafer with micro-topography where the common practice is a uniform density of patterns or features (e.g., trenches or holes), with the additional DOF as the feature density along the wafer. A non-uniform density is designed with the objective of improving the uniformity; as a consequence, the differences in the profiles of the deposited films in all the features on the wafer will be compensated. A multi-scale modeling framework is utilized for the design. The case study is aluminum metal-organic (MO)CVD from dimethylethylamine alane under conditions of low macroscopic uniformity. Compared to a uniform density of the same number of trenches, the multi-scale computations predict that the designed density of features, namely trenches, induces a remarkable improvement of both the macroscopic uniformity and the number of trenches on the wafer where the uniformity exceeds 0.95. The methodology is applied to features, i.e., the simplest unit cell of topography on a wafer, even if practical implementation of the variation of feature density is difficult. The same methodology can be applied to design the density of a cluster of features comprising a single device, or a die on the wafer.

The tilted fiber Bragg grating (TFBG), as a versatile and robust tool for many sensing applications with a particular focus on vapor deposition processes, is reviewed. Recent work employing the TFBG as an optical probe for monitoring the metal-organic (MO)CVD of noble-metal, single-source precursors is discussed extensively. This work also establishes the broad scope that utilizes TFBGs and other optical fiber configurations to interrogate thin film growth and the associated optical properties. While it cannot possibly cover the full scope of applications with respect to the TFBG device, this review highlights the recent advances of TFBG-based sensing for CVD, and progress towards the applicability of TFBGs as evanescent field-based sensors.