Carboxylic Acids and Esters as Scaffold for Cavities in Porous Single Layer Anti-Reflective Coatings of Silica-Titania with Excellent Optical and Mechanical Properties

Anti-reflective (AR) single layer of silica-titania (SiO2-TiO2) coatings were obtained from sols containing pyromellitic dianhydride (PMDA) derivatives and Ti and Si precursors on glass substrate by dip-coating method. The coatings showed very high optical quality and the transmission was improved to up to 98.5%. Furthermore, the coatings also presented good mechanical stability.

Dual in-situ observation of tribochemical and morphological evolution of single-layer WS_(2)and multi-layer WS_(2)/C coatings

The outstanding tribological performance of transition metal dichalcogenides(TMDs)is attributed to their unique sandwich microstructure and low interlayer shear stress.This advantageous structure allows TMDs to demonstrate exceptional friction reduction properties.Furthermore,the incorporation of TMDs and amorphous carbon(a-C)in multi-layer structures shows excellent potential for further enhancing tribological and anti-oxidation properties.Amorphous carbon,known for its high ductility,chemical inertness,and excellent wear resistance,significantly contributes to the overall performance of these multi-layer coatings.To gain an in-depth understanding of the tribological mechanism and evolution of TMDs’multi-layer coatings,a dual in-situ analysis was carried out using a tribometer equipped with a 3D laser microscope and a Raman spectrometer.This innovative approach allowed for a comprehensive evolution of the tribological,topographical,and tribochemical characteristics of both single-layer WS_(2)and multi-layer WS_(2)/C coatings in real time.The findings from the dual in-situ tribotest revealed distinct failure characteristics between the single-layer WS_(2)coating and the multi-layer WS_(2)/C coating.The single-layer WS_(2)coating predominantly experienced failure due to mechanical removal,whereas a combination of mechanical removal and tribochemistry primarily influenced the failure of the multi-layer WS_(2)/C coating.The tribological evolution process of these two coatings can be classified into four stages on the basis of their tribological behavior:the running-in stage,stable friction stage,re-deposition stage,and lubrication failure stage.Each stage represents a distinct phase in the tribological behavior of the coatings and contributes to our understanding of their behavior during sliding.

Micro and nano-enabled approaches to improve the performance of plasma electrolytic oxidation coated magnesium alloys

Magnesium(Mg)and its alloys have become a hot research topic in various industries owing to the specific physical and chemical properties.However,high corrosion rate is considered the key lifetime-limiting.Plasma electrolytic oxidation(PEO)method is a simple strategy to deposit an oxide layer on the surface of light metals such as magnesium alloys,to control corrosion rate and promote some other properties,depending on their performances.Nevertheless,their features including their micropore size,distribution,and interconnectivity,and microcracks have not been improved to an acceptable level to support long-term performances of the magnesium-based substrates.Studies have introduced micro/nano-enabled approaches to enhance various properties of PEO coatings such as corrosion resistance,tribological properties,self-healing ability,bioactivity,biocompatibility,antibacterial properties,or catalytic performances.These strategies consist of incorporating of micro and nanoparticles into the PEO layers to produce multi-functional surfaces or the formation of multi-layered coatings to cover the defects of PEO coatings.In this perspective,the present paper aims to overview various nano/micro-enabled strategies to promote the properties of PEO coatings on magnesium alloys.The main focus is given to the functional changes that occurred in response to the incorporation of various types of nano/micro-structures into the PEO coatings on magnesium alloys.

Highly transparent anti-reflection coating enhances the underwater efficiency and stability of perovskite solar modules

Perovskite solar cells have shown great potential in the field of underwater solar cells due to their excellent optoelectronic properties;however,their underwater performance and stability still hinder their practical use.In this research,a 1H,1H,2H,2H-heptadecafluorodecyl acrylate(HFDA)anti-reflection coating(ARC)was introduced as a high-transparent material for encapsulating perovskite solar modules(PSMs).Optical characterization results revealed that HFDA can effectively reduce reflection of light below 800 nm,aiding in the absorption of light within this wavelength range by underwater solar cells.Thus,a remarkable efficiency of 14.65%was achieved even at a water depth of 50 cm.And,the concentration of Pb^(2+)for HFDA-encapsulated film is significantly reduced from 186 to 16.5 ppb after being immersed in water for 347 h.Interestingly,the encapsulated PSMs still remained above 80%of their initial efficiency after continuous underwater illumination for 400 h.Furthermore,being exposed to air,the encapsulated PSMs maintained 94%of their original efficiency after 1000 h light illumination.This highly transparent ARC shows great potentials in enhancing the stability of perovskite devices,applicable not only to underwater cells but also extendable to land-based photovoltaic devices.

The investigation of DARC etch back in DRAM capacitor oxide mask opening

Opening the silicon oxide mask of a capacitor in dynamic random access memory is a critical process on a capacitive coupled plasma(CCP)etch tool.Three steps,dielectric anti-reflective coating(DARC)etch back,silicon oxide etch and strip,are contained.To acquire good performance,such as low leakage current and high capacitance,for further fabricating capacitors,we should firstly optimize DARC etch back.We developed some experiments,focusing on etch time and chemistry,to evalu-ate the profile of a silicon oxide mask,DARC remain and critical dimension.The result shows that etch back time should be con-trolled in the range from 50 to 60 s,based on the current equipment and condition.It will make B/T ratio higher than 70%mean-while resolve the DARC remain issue.We also found that CH_(2)F_(2) flow should be~15 sccm to avoid reversed CD trend and keep in-line CD.

Contact etch process optimization for RF process wafer edge yield improvement

Radio-frequency(RF)process products suffer from a wafer edge low yield issue,which is induced by contact opening.A failure mechanism has been proposed that is based on the characteristics of a wafer edge film stack.The large step height at the wafer's edge leads to worse planarization for the sparse poly-pattern region during the inter-layer dielectric(ILD)chemical mechanical polishing(CMP)process.A thicker bottom anti-reflect coating(BARC)layer was introduced for a sparse poly-pattern at the wafer edge region.The contact open issue was solved by increasing the break through(BT)time to get a large enough window.Well profile and resistance uniformity were obtained by contact etch recipe optimization.

Microstructure and optical properties of TiO_2 thin films deposited at different oxygen flow rates

To research the influence of oxygen flow rate on the structural and optical properties of TiO2 thin film,TiO2 films on glass were deposited by reactive magnetron sputtering.The microstructure and optical properties were measured by X-ray diffractometry,AFM and UV-VIS transmittance spectroscopy,respectively.The results show that the films deposited at oxygen flow rate of 10 mL/min has the lowest roughness and the highest transmittance.The absorption angle shifts to longer wavelengths as oxygen flow rates increase from 5 to 10 mL/min,then to shorter ones as the oxygen flow rate increase from 10 to 30 mL/min.The band gap is 3.38 eV,which is nearly constant in the experiment.For the TiO2 thin films deposited at 10 mL/min of oxyge flow rate,there are nano-crystalline structures,which are suitable for anti-reflection(AR) coating in the solar cells structure system.

Monolithic crystalline silicon solar cells with SiN_x layers doped with Tb^(3+) and Yb^(3+) rare-earth ions

In this study, we propose the fabrication of monolithic crystalline silicon solar cells with Tb^(3+) and Yb^(3+)-doped silicon nitride(SiN_x) layers by low-cost screen-printing methods. The performances of c-Si solar cells can be enhanced by rare-earth ions doped SiN_x layers via the mechanism of spectrum conversion.These SiN_x doped and codoped thin films were deposited by reactive magnetron co-sputtering and integrated as the antireflection coating layers in c-Si solar cells. The characterizations of SiN_x, SiN_x:Tb^(3+) tand SiN_x:Tb^(3+)-Yb^(3+) thin films were conducted by means of photoluminescence, Rutherford backscattering spectroscopy, Ellipsometry spectroscopy and Fourier transform infrared measurements. Their composition and refractive index was optimized to obtain good anti-reflection coating layer for c-Si solar cells.Transmission electron microscopy performs the uniform coatings on the textured emitter of c-Si solar cells. After the metallization process, we demonstrate monolithic c-Si solar cells with spectrum conversion layers, which lead to a relative increase by 1.34% in the conversion efficiency.

Integration of silicon nanowires in solar cell structure for efficiencyenhancement: A review

Silicon nanowires (SiNWs) are a one-dimensional semiconductor, which shows promising applications indistinct areas such as photocatalysis, lithium-ion batteries, gas sensors, medical diagnostics, drug delivery,and solar cell. From an implementation point of view, SiNWs are fabricated using either a topdownor bottom-up approach, and SiNWs are both optically and electronically active. SiNWs enhancesthe efficiency of the solar cell due to better electronic, optical, and physical properties that can becontrolled by tuning the physical dimensions of SiNWs. The SiNWs shows an inherent capability to beutilized in radial or coaxial p-n junction solar cells, to stipulate orthogonal photon absorption, antireflection,and enhanced carrier collection. This paper reviews property-control of SiNWs, theirvarious types of incorporation in a solar cell, and the reasons behind enhanced efficiency.

Detection of small delamination in mullite/Si/SiC model EBC system by pulse thermography

The pulse thermography(PT) technique was applied to the detection of the delamination of a multi-layered coating system composed of mullite/Si onto a reaction-bonded Si C substrate. The potential evaluation was carried out in order to detect internal delamination in multi-layered material system. Moreover, the observation of the cross sections and 3D views obtained by X-ray computed tomography(CT) indicated that the delamination occurred at the interface between the top coat and the bond coat layers. The changes in the temperature distribution obtained by PT indicated the existence of a delamination area in the top coat layer of the mullite. In particular, the lower temperature region corresponded to the delamination area. The experimental results confirmed that the PT technique is effective with respect to the internal delamination of multi-layered coating system.

Optical and electrical properties of porous silicon layer formed on the textured surface by electrochemical etching

Porous silicon （PS） layers were formed on textured crystalline silicon by electrochemical etching in HF- based electrolyte. Optical and electrical properties of the TMAH textured surfaces with PS formation are studied. Moreover, the influences of the initial structures and the anodizing time on the optical and electrical properties of the surfaces after PS formation are investigated. The results show that the TMAH textured surfaces with PS formation present a dramatic decrease in reflectance. The longer the anodizing time is, the lower the reflectance. Moreover, an initial surface with bigger pyramids achieved lower reflectance in a short wavelength range. A minimum reflectance of 3.86% at 460 nm is achieved for a short anodizing time of 2 min. Furthermore, the reflectance spectrum of the sample, which was etched in 3 vol.% TMAH for 25 min and then anodized for 20 min, is extremely flat and lies between 3.67% and 6.15% in the wavelength range from 400 to 1040 nm. In addition, for a short anodizing time, a slight increase in the effective carrier lifetime is observed. Our results indicate that PS layers formed on a TMAH textured surface for a short anodization treatment can be used as both broadband antireflection coatings and passivation layers for the application in solar cells.