Search results for "Passivation"
showing 10 items of 91 documents
Character of the Reaction between Molecular Hydrogen and a Silicon Dangling Bond in Amorphous SiO2
2007
The passivation by diffusing H2 of silicon dangling bond defects (E′ centers, O3tSi•) induced by laser irradiation in amorphous SiO2 (silica) is investigated in situ at several temperatures. It is found that the reaction between the E′ center and H2 requires an activation energy of 0.39 eV and that its kinetics is not diffusionlimited. The results are compared with previous findings on the other fundamental paramagnetic point defect in silica, the oxygen dangling bond, which features completely different reaction properties with H2. Furthermore, a comparison is proposed with literature data on the reaction properties of surface E′ centers, of E′ centers embedded in silica films, and with th…
Kinetics of Bulk Lifetime Degradation in Float‐Zone (FZ) Silico n : Fast Activation and Annihilation of Grown‐In Defects and the Role of Hydrogen vs …
2020
Float-zone (FZ) silicon often has grown-in defects that are thermally activated in a broad temperature window (≈300–800 °C). These defects cause efficient electron-hole pair recombination, which deteriorates the bulk minority carrier lifetime and thereby possible photovoltaic conversion efficiencies. Little is known so far about these defects which are possibly Si-vacancy/nitrogen-related (VxNy). Herein, it is shown that the defect activation takes place on sub-second timescales, as does the destruction of the defects at higher temperatures. Complete defect annihilation, however, is not achieved until nitrogen impurities are effused from the wafer, as confirmed by secondary ion mass spectro…
ZnS Ultrathin interfacial layers for optimizing carrier management in Sb2S3-based photovoltaics
2021
Antimony chalcogenides represent a family of materials of low toxicity and relative abundance, with a high potential for future sustainable solar energy conversion technology. However, solar cells based on antimony chalcogenides present open-circuit voltage losses that limit their efficiencies. These losses are attributed to several recombination mechanisms, with interfacial recombination being considered as one of the dominant processes. In this work, we exploit atomic layer deposition (ALD) to grow a series of ultrathin ZnS interfacial layers at the TiO2/Sb2S3 interface to mitigate interfacial recombination and to increase the carrier lifetime. ALD allows for very accurate control over th…
Impurity analyses of silicon wafers from different manufacturing routes and their impact on LID of finished solar cells
2013
Summarizes the measurements of impurity concentrations in directionally solidified silicon ingots from different feedstocks. The substitutional Carbon and interstitial Oxygen are measured on as-sawn wafers using FTIR. Active iron concentration is mapped on a-Si:H passivated wafers. It is observed that these impurities present in Elkem Solar Grade Silicon (ESS™) concentrations are comparable to the standard polysilicon which are in the acceptable ranges for silicon for solar industry. The measured LID of the finished solar cells is also comparable.
Thermal atomic layer deposition of AlOxNy thin films for surface passivation of nano-textured flexible silicon
2019
Abstract Aluminum oxynitride (AlOxNy) films with different nitrogen concentration are prepared by thermal atomic layer deposition (ALD) for flexible nano-textured silicon (NT-Si) surface passivation. The AlOxNy films are shown to exhibit a homogeneous nitrogen-doping profile and the presence of an adequate amount of hydrogen, which is investigated by Time-of-Fight Elastic Recoil Detection Analysis (ToF-ERDA). The effective minority carrier lifetimes are measured after the NT-Si surface passivation; the minimum surface recombination velocity (SRV) of 5 cm-s−1 is achieved with the AlOxNy film in comparison to the Al2O3 and AlN films (SRV of 7–9 cm-s−1). The better SRV with AlOxNy film is due …
Photo-electrochemical investigation of anodic oxide films on cast Ti–Mo alloys. I. Anodic behaviour and effect of alloy composition
2009
Abstract The anodic behaviour of cast Ti–Mo alloys, having different Mo contents (6–20 wt.%), was investigated in acidic and neutral aerated aqueous solutions. All sample showed a valve-metal behaviour, owing to formation and thickening of barrier-type anodic oxides displaying interference colours. Growth kinetics of passive films is influenced by both anodizing electrolyte and composition of the starting alloy. This last parameter was found to change also the solid-state properties of the films, explored by photoelectrochemical and impedance spectroscopy experiments. Thicker films ( U f = 8 V/MSE) grown on alloys richer in Mo showed more resistive character and a photocurrent sign inversi…
Semiconductor electrochemistry approach to passivity and passivity breakdown of metals and metallic alloys
2004
AbstractA critical appraisal of the use of the theory of semiconductors in characterising passive films on metals and alloys is provided, with special emphasis on the use of Mott-Schottky theory for the location of characteristic energy levels of the passive film-electrolyte junction. Some inconsistencies between theory and experimental results in the case of thin passive films are discussed together with possible alternative ways for overcoming such problems. The role of semiconducting properties in determining the pitting behaviour of passive films on W in solutions containing halide is presented and discussed. The validity of a recently proposed correlation between the solid state proper…
Particle surface engineering effect on the mechanical, optical and photoluminescent properties of ZnO/vinyl-ester resin nanocomposites
2007
Zinc oxide (ZnO) nanoparticles functionalized with a bi-functional coupling agent methacryloxypropyl-trimethoxysilane (MPS) were used to fabricate a vinyl-ester resin polymeric nanocomposite, which shows an improved interfacial interaction between the particle and matrix. As a result, in comparison to the unmodified particle-filled nanocomposites, the functionalized particle-filled composites possessed higher resistance to thermal degradation, and demonstrated improved UV shielding and enhanced photoluminescent properties. The more uniform particle dispersion, passivation of the particle surface with MPS and increased oxygen vacancies were justified to contribute to the increased thermal st…
Quartz Crystal Microbalance And Electrical Impedance Characterization Of Nickel Dissolution Process.
2005
Abstract. The anodic nickel dissolution in acid media is analysed by means of EQCM and EIS techniques. The experimental impedance spectra have been fitted to the equivalent circuit which corresponds to two consecutive electron transfers followed by a Ni(II) desorption. That way rate constants and surface concentrations of the Ni(0) and Ni(I) species are obtained. EQCM also provides information about the mechanism of deposition and passivation of nickel as well as the hydrogen evolution.
Simultaneous Anodic Dissolution and Passivation of Nickel in Moderate Acid Medium
2006
The EQCM results show that nickel electrodissolution and nickel passivation occur simultaneously in a sulphate acid media of pH = 3.5. Mass balances have been done from the instantaneous F(dm/dQ) function. The fitting of the experimental i = f(E) and -dm/dt = g(E) curves to the theoretical equations allow to obtain information about the kinetic parameters and the molecular mass of the species involved in the electrochemical processes.