scholarly journals Ellipsometric study of passive and anodic oxide films formed on Ti and Nb electrodes

2016 ◽  
Vol 5 (4) ◽  
pp. 221 ◽  
Author(s):  
Ljubomir Dimitar Arsov ◽  
Irena Mickova
Keyword(s):  
Barrier Properties ◽  
Anodic Oxide ◽  
Passive Films ◽  
Potential Cycling ◽  
Potential Region ◽  
Passive Transition ◽  
Multiple Cycle ◽  
Pre Treatment ◽  
Voltammetry Methods

<p class="PaperAbstract"><span lang="EN-US">Electrochemical formation of passive films and active/passive transition on Ti and Nb metal surfaces in various concentrations of H<sub>2</sub>SO<sub>4</sub> and KOH solutions was investigated using potentiostatic and cyclic voltammetry methods. By simultaneous electrochemical and in-situ ellipsometric measurements the coefficients of film thickness growth of passive films in the potential region from -1.5 V to 4 V were determined. Results indicate the strong influence of the concentration and electrolyte nature to the active/passive transitions and stability of passive films. The influence of cathodic pre-treatment on the passive films dissolution and appearance of the reactivation peaks during the reverse potential cycling were shown. By multiple cycle sequences in which the final anodic potential was gradually enlarged, the barrier properties of passive films on investigated electrodes were confirmed. The electrochemical and ellipsometric data showed that the passive films formed on Nb electrode are more resistant that passive films formed on Ti electrode, especially in higher concentrations of investigated aggressive solutions.</span></p><br />

scholarly journals Electrochemical characterization of the passive films formed on niobium surfaces in H2SO4 solutions

2006 ◽  
Vol 71 (2) ◽  
pp. 177-187 ◽  
Author(s):  
Irena Arsova ◽  
Abdurauf Prusi ◽  
Toma Grcev ◽  
Ljubomir Arsov
Keyword(s):  
Cyclic Voltammetry ◽  
Passive Film ◽  
Chemical Structure ◽  
Open Circuit ◽  
Passive Films ◽  
Anodic Films ◽  
Potential Region ◽  
Passive Transition ◽  
Cyclic Voltammetry Data

The electrochemical formation and characteristics of passive films on niobium surfaces in aqueous H2SO4 solutions were studied using open circuit potential and cyclic voltammetry. In the potential region between -1.0 and 1.2 V(NHE), the cyclic voltammetry data showed that the active/passive transition involves slow metal dissolution followed by the formation of semiconducting passive oxide films. The possible electrochemical reactions and the change of the oxidation steps of some niobium oxides occurring in the passive film during the polarization are proposed. A strong influence of the natural air-formed oxide film on the chemical composition of the passive film was shown. This influence makes chemical structure of thin passive films more complicated than that of thick anodic films. It is shown that the passive films consists of more or less stable oxides, such as NbO, NbO2 and Nb2O5. The Raman spectra revealed that the thin passive films were amorphous, while the films formed at higher voltages consist, primarily, of well-crystallized Nb2O5.

Reliability, Properties and Microstructure of W80Ti20 Diffusion Barriers Between Al-Based Metallizations and Si.

1992 ◽  
Vol 260 ◽  
Author(s):  
A. G. Dirks ◽  
R. A. M. Wolters ◽  
A. E. M. De Veirman
Keyword(s):  
Barrier Properties ◽  
Diffusion Barriers ◽  
Columnar Microstructure ◽  
Compound Formation ◽  
Actual Distribution ◽  
Alloy Films ◽  
The Relationship ◽  
Post Deposition ◽  
Deposition Conditions

ABSTRACTTungsten-rich W-Ti (or W-Ti-N) alloy films are known for their applicability as diffusion barriers in advanced silicon technology, especially in the case of aluminium-based metallizations. For a wide variety of deposition conditions and post-deposition anneal treatments these refractory-metal barriers show a columnar microstructure. In contact with aluminium the W-Ti films do not form absolute barriers, because of mutual diffusion resulting in compound formation. The reactivity of the W-Ti barriers with the Al99Si1 interconnect has been studied by in-situ resistance measurements in vacuum at temperatures of approximately 450 °C (for W-Ti alloy films) and 475 °C (for W-Ti-N alloy films). In this paper new results dealing with the relationship between deposition conditions, microstructure and barrier properties will be discussed. Furthermore, it will be shown that the actual distribution of the titanium atoms in the tungsten matrix has a substantial influence on the reactivity of the barrier film with the Al99Si1 interconnect.

scholarly journals Poly(3,4-ethylenedioxythiophene) Electrosynthesis in the Presence of Mixtures of Flexible-Chain and Rigid-Chain Polyelectrolytes

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3866
Author(s):  
Varvara Kabanova ◽  
Oxana Gribkova ◽  
Alexander Nekrasov
Keyword(s):  
Additive Effect ◽  
Potential Cycling ◽  
Flexible Chain ◽  
Chain Component ◽  
Ammonia Sensing ◽  
Rigid Chain ◽  
Vis Spectroscopy ◽  
Polyaniline Films ◽  
Spectroelectrochemical Properties

The electrochemical synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) was first carried out in the presence of mixtures of flexible-chain and rigid-chain polyacids and their Na-salts. Earlier on with the example of polyaniline, we have shown the non-additive effect of the rigid-chain component of polyacid mixtures on the electrodeposition of polyaniline films, their morphology and spectroelectrochemical properties. In this study, we confirmed the non-additive effect and showed that such mixed PEDOT–polyelectrolyte films possess unique morphology, spectroelectrochemical and ammonia sensing properties. The electrosynthesis was carried out in potential cycling, galvanostatic and potentiostatic regimes and monitored by in situ UV–Vis spectroscopy. UV–Vis spectroelectrochemistry of the obtained PEDOT–polyelectrolyte films revealed the dominating influence of the rigid-chain polyacid on the electronic structure of the mixed complexes. The mixed PEDOT–polyacid films demonstrated the best ammonia sensing performance (in the range of 5 to 25 ppm) as compared to the films of individual PEDOT–polyelectrolyte films.

scholarly journals P078 Oral Appliance Fabrication Settings Impact Treatment Efficacy

2021 ◽  
Vol 2 (Supplement_1) ◽  
pp. A46-A46
Author(s):  
D Levendowski ◽  
E Sall ◽  
W Odom ◽  
B Beine ◽  
D Cruz Arista ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Sleep Apnea ◽  
Treatment Outcomes ◽  
Body Mass ◽  
Treatment Efficacy ◽  
Oral Appliance ◽  
Chi Squared ◽  
Pre Treatment ◽  
The Impact

Abstract Purpose Assess the impact of custom oral appliance (CA) fabrication settings on treatment outcomes. Methods CPAP-intolerant patients completed a two-night home-sleep-apnea study (HSAT); Night1=baseline, Night2=Apnea Guard® trial appliance (AG). The AG vertical-dimension-of-occlusion (VDO) selection was based on tongue-scallop (women=5.5/6.5 mm, men= 6.5/8.0 mm), with a target protrusion of 70% from neutral-maximum while in situ. Study1 CA VDO was dependent on sex (women=2.5 mm, men=5 mm), with protrusion set using a George-Gauge measured 70% from maximum retrusion-protrusion with dentist-directed titration. Study2 CA was fabricated to the AG VDO and target protrusion bite-registration. Efficacy HSATs were conducted after completion of Study1 CA titration with vertical-elastics optional, and at the AG target protrusion with vertical-elastics mandatory in Study2. Statistics included Mann-Whitney, Chi-squared, and Bland-Altman analyses. Results The Study1 (n=84) and Study2 (n=46) distributions were equivalent for tongue-scallop (64/63%) and sex (women=45/41%), however, noted differences in age (53.8±11.9 vs. 58.4±12.2; P=0.052), body-mass-index (29.4±5.7 vs. 27.8±4.0; P=0.128) and pre-treatment AHI severities (24.6±14.4 vs. 29.2±17.4 events/h; P=0.155) were observed. The Bland-Altman biases were significant different (Study1=4.2±7.8 vs. Study2=1.3±7.0 events/h, P=0.035). The significant Study1 differences between the CA vs. AG AHIs (12.3±9.2 vs. 8.2±5.9 events/h, P&lt;0.0002) were not apparent in Study2 (11.7±8.0 vs. 10.4±6.7 events/h, P=0.362), however, the Study2 AG AHI values were higher (P=0.055). Discussion Despite the trend toward greater Study2 pre-treatment and AG AHI severities, CA treatment efficacy was equivalent to the AG once VMO was controlled and fabricated using the AG VDO and protrusion bite-registration. These findings confirmed CA fabrication settings impact treatment outcomes.

scholarly journals An In Situ Reflection Mode Quick Scanning EXAFS Study of Anodic Oxide Layer Formation on Silver

1997 ◽  
Vol 7 (C2) ◽  
pp. C2-717-C2-722 ◽  
Author(s):  
D. Hecht ◽  
P. Borthen ◽  
R. Frahm ◽  
H.-H. Strehblow
Keyword(s):  
Oxide Layer ◽  
Anodic Oxide ◽  
Layer Formation ◽  
Reflection Mode ◽  
Exafs Study ◽  
Anodic Oxide Layer

Impact of In Situ NH3 pre-treatment of LPCVD SiN passivation on GaN HEMT performance

2022 ◽  
Author(s):  
Ding-Yuan Chen ◽  
Axel R Persson ◽  
Kai Hsin Wen ◽  
Daniel Sommer ◽  
Jan Gruenenpuett ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Low Pressure ◽  
Untreated Sample ◽  
Pressure Chemical ◽  
Gan Hemts ◽  
Pre Treatment ◽  
The Impact

Abstract The impact on the performance of GaN HEMTs of in situ ammonia (NH3) pre-treatment prior to the deposition of silicon nitride (SiN) passivation with low-pressure chemical vapor deposition is investigated. Three different NH3 pre-treatment durations (0, 3, and 10 minutes) were compared in terms of interface properties and device performance. A reduction of oxygen at the interface between SiN and epi-structure is detected by Scanning Transmission Electron Microscopy-Electron Energy Loss Spectroscopy measurements in the sample subjected to 10 minutes of pre-treatment. The samples subjected to NH3 pre-treatment show a reduced surface-related current dispersion of 9 % (compared to 16% for the untreated sample), which is attributed to the reduction of oxygen at the SiN/epi interface. Furthermore, NH3 pre-treatment for 10 minutes significantly improves the current dispersion uniformity from 14.5 % to 1.9 %. The reduced trapping effects result in a high output power of 3.4 W/mm at 3 GHz (compared to 2.6 W/mm for the untreated sample). These results demonstrate that the in situ NH3 pre-treatment before low-pressure chemical vapor deposition of SiN passivation is critical and can effectively improves the large-signal microwave performance of GaN HEMTs.

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