scholarly journals Synthesis, Properties and Aging of ICP-CVD SiCxNy:H Films Formed from Tetramethyldisilazane

Coatings ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 80
Author(s):  
Maksim N. Chagin ◽  
Veronica S. Sulyaeva ◽  
Vladimir R. Shayapov ◽  
Aleksey N. Kolodin ◽  
Maksim N. Khomyakov ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Film Growth ◽  
Film Surface ◽  
Ambient Air ◽  
Fused Silica ◽  
Element Composition ◽  
Film Deposition ◽  
Silicon Carbonitride ◽  
Vapor Deposition Technique

Amorphous hydrogenated silicon carbonitride films were synthesized on Si(100), Ge(111), and fused silica substrates using the inductively coupled plasma chemical vapor deposition technique. 1,1,3,3-tetramethyldisilazane (TMDSN) was used as a single-source precursor. The effect of the precursor’s pressure in the initial gas mixture, the substrate temperature, the plasma power, and the flow rate of nitrogen gas as an additional reagent on the film growth rate, element composition, chemical bonding, wettability of film surface, and the optical and mechanical properties of a-SiCxNy:H films was investigated. In situ diagnostic studies of the gas phase have been performed by optical emission spectroscopy during the film deposition process. The long-term stability of films was studied over a period of 375 days. Fourier-transform infrared (FTIR) and X-ray energy dispersive spectroscopy (EDX), and wettability measurements elucidated the oxidation of the SiCxNy:H films deposited using TMDSN + N2 mixture. Films obtained from a mixture with argon had high stability and maintained the stability of element composition after long-term storage in ambient air.

Ultrafast Deposition of Crystalline Si Films Using a High Density Microwave Plasma

2010 ◽  
Vol 1245 ◽  
Author(s):  
Haijun Jia ◽  
Michio Kondo
Keyword(s):  
Film Growth ◽  
Microwave Plasma ◽  
Crystalline Silicon ◽  
Plasma Source ◽  
Ambient Air ◽  
Film Deposition ◽  
High Density ◽  
Silicon Films ◽  
Reduced Pressure ◽  
Si Films

AbstractA multi-pressure microwave plasma source is developed and is applied for the fast deposition of crystalline silicon films. In this paper, the plasma source is diagnosed firstly. Electron density, electron temperature and discharge gas temperature of the plasmas generated in ambient air are studied using optical emission spectroscopy (OES) method. By using the high density microwave plasma source, depositions of crystalline silicon films from SiH4+He mixture at reduced pressure conditions are investigated systematically. After optimizing the film deposition conditions, highly crystallized Si films are deposited at a rate higher than 700 nm/s. We also find that the deposited films are fully crystallized and crystalline structure of the deposited film evolves along the film growth direction, i.e. large grains in surface region while small grains in the bottom region of the film. Based on the observed results, a possible mechanism, the annealing-assisted plasma-enhanced chemical vapor deposition, is proposed to describe the film growth process.

FORMATION OF CRACK-LIKE DIFFUSION WEDGES AND COMPRESSIVE STRESS EVOLUTION DURING THIN FILM GROWTH WITH INHOMOGENEOUS GRAIN BOUNDARY DIFFUSIVITY

2009 ◽  
Vol 01 (01) ◽  
pp. 1-19 ◽  
Author(s):  
TANMAY K. BHANDAKKAR ◽  
ERIC CHASON ◽  
HUAJIAN GAO
Keyword(s):  
Thin Film ◽  
Grain Boundary ◽  
Compressive Stress ◽  
Moving Boundary ◽  
Boundary Diffusion ◽  
Film Growth ◽  
Film Surface ◽  
Film Deposition ◽  
Stress Evolution ◽  
Growth Interruption

We consider the effects of inhomogeneous grain boundary (GB) diffusivity on the formation of crack-like grain boundary diffusion wedges and evolution of compressive stress during the growth of a polycrystalline thin film on a substrate with a perfectly bonded film-substrate interface. The problem is formulated as a class of moving boundary diffusion problems with fully coupled elasticity, GB diffusion and film growth. The inhomogeneous GB mobility leads to a set of hypersingular integro-differential equations which are solved by a special numerical scheme. During the film growth, atoms diffuse into the GBs due to the tensile coalescence stress in the film associated with GB formation. We show that, at deposition rates comparable to the diffusion time scale, such GB diffusion leads to temporal decay of GB traction and induces crack-like singular stress concentration at the roots of the GBs. For a slowly growing high mobility thin film, the stress intensity factor near the tip of the diffusion wedge is comparable to that of a GB diffusion wedge under annealing conditions and can lead to nucleation of dislocations, which in turn can influence stress evolution during film growth. Furthermore, the higher chemical potential at the film surface can overdrive adatoms into GBs and result in a final compressive stress in the film. Our simulations on cyclic film deposition and growth interruption processes qualitatively reproduced the experimentally observed behavior of GB mobility on the Stress-Thickness evolution during deposition, the stress relaxation during growth interruption, as well as the dependence of steady state stress on the deposition rate.

scholarly journals Optimization of passivation in AlGaN/GaN heterostructure microwave transistor fabrication by ICP CVD

2020 ◽  
Vol 6 (2) ◽  
pp. 71-75
Author(s):  
Anastasia A. Sleptsova ◽  
Sergey V. Chernykh ◽  
Dmitry A. Podgorny ◽  
Ilya A. Zhilnikov
Keyword(s):  
Inductively Coupled Plasma ◽  
Gas Flow ◽  
Film Growth ◽  
Chemical Vapor ◽  
High Electron Mobility Transistors ◽  
Film Deposition ◽  
High Electron ◽  
Rf Power ◽  
Plasma Chemical Vapor Deposition ◽  
Gan Heterostructure

We have studied the effect of silicon nitride (SiN) dielectric passivating film deposition by inductively coupled plasma chemical vapor deposition (ICP CVD) on the parameters of AlGaN/GaN heterostructure high electron mobility transistors (HEMT). Study of the parameters of the dielectric layers has allowed us to determine the effect of RF and ICP power and working gas flow ratio on film growth rate and structural perfection, and on the current vs voltage curves of the passivated HEMT. The deposition rate changes but slightly with an increase in RF power but increases with an increase in ICP power. Transistor slope declines considerably with an increase in RF power: it is the greatest at minimum power RF = 1 W. In the beginning of growth even at a low RF power (3 W) the transistor structure becomes completely inoperable. Dielectric deposition for HEMT passivation should be started at minimum RF power. We have developed an AlGaN/GaN microwave HEMT passivation process providing for conformal films and low closed transistor drain–source currents without compromise in open state transistor performance: within 15 and 100 mA, respectively, for a 1.25 and 5 mm common T-gate (Ug = –8 V and Ud-s = 50 V).

Energy Use Considerations in the Activated Sludge Process in Los Angeles, U.S.A.

1984 ◽  
Vol 16 (10-11) ◽  
pp. 107-117
Author(s):  
WF Garber
Keyword(s):  
Los Angeles ◽  
Energy Use ◽  
Energy Savings ◽  
Treatment Plant ◽  
Ambient Air ◽  
Fused Silica ◽  
Energy Costs ◽  
Long Term Treatment ◽  
Standard Design

The City of Los Angeles has four secondary-tertiary treatment plants receiving wastewater flows of 1,590,000, 151,000, 114,000 and 75,000 m3/d. Operational difficulties with fine bubble air diffuser combined with low energy costs had resulted in the use of 4–5% efficiency diffusers as standard design. Increasing energy costs made revaluation of higher efficiency diffusers necessary. Long term treatment plant tests of ceramic domes, fused silica tubes and jet diffusers indicated that long term 8–10% air diffusion efficiency was possible. Energy savings of the order of 40% could be achieved by such diffuser retrofit. The type of diffuser to use would depend upon ambient air and waste characteristics, tank design and the sizing of existing equipment such as blowers. Data from respirometer studies in operating plants indicated a further 10–30% decrease in energy use could arise from computer control leading to an equalized F/M ration throughout each day. Further tests of this possibility are planned.

Radical-surface interactions during film deposition: A sticky situation?

2006 ◽  
Vol 78 (6) ◽  
pp. 1187-1202 ◽  
Author(s):  
Dongping Liu ◽  
Ina T. Martin ◽  
Jie Zhou ◽  
Ellen R. Fisher
Keyword(s):  
Film Growth ◽  
High Surface ◽  
Film Surface ◽  
Chemical Vapor ◽  
Electronic Configuration ◽  
Surface Reactivity ◽  
Film Deposition ◽  
Electron Configuration ◽  
Plasma Parameters ◽  
Temperature Plasma

Our imaging of radicals interacting with surfaces (IRIS) method was used to investigate radical-surface reactions during low-temperature plasma-enhanced chemical vapor deposition (PECVD) processes. Special emphasis was placed on the analysis of surface reactivities for CH, SiH, CN, NH, NH2, CF2, and SiCl2 radicals during film growth. The effects of plasma parameters, such as radio frequency (rf) power and gas composition, substrate temperature, and substrate bias on radical-surface reactivity were analyzed. Different radicals exhibit different behavior at the surface of a depositing film. Specifically, CH, SiH, and CN are "sticky", with high surface reactivities. In contrast, other species such as NH, CF2, and SiCl2 do not stick to the surface of growing films and, in some cases are actually generated at the surface of the depositing film. Different plasma systems and parameters can have an effect on the stickiness of some of these species. Our IRIS measurements indicate a molecule's surface sticking probability may also be related to the molecule's electronic configuration and stability, with the most reactive species being molecules with a doublet electron configuration. In contrast, the singlet species examined here tend to be generated at the surface during film deposition. Our results also indicate that when a molecule scatters with greater than 100 % probability, it is likely to be strongly affected by energetic ion bombardment of the film surface.

41. Diffusion Badges as a Long-Term, Low-Level Method of Ambient Air Analysis

2005 ◽  
Author(s):  
K. Parker ◽  
S. Rose-Pehrsson ◽  
D. Kidwell
Keyword(s):  
Ambient Air ◽  
Air Analysis ◽  
Low Level ◽  
Level Method

scholarly journals Acute and chronic exposure to air pollution in relation with incidence, prevalence, severity and mortality of COVID-19: a rapid systematic review

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Patrick D. M. C. Katoto ◽  
Amanda S. Brand ◽  
Buket Bakan ◽  
Paul Musa Obadia ◽  
Carsi Kuhangana ◽  
...  
Keyword(s):  
Air Pollution ◽  
Chronic Exposure ◽  
Ambient Air ◽  
Short Term ◽  
Incidence And Mortality ◽  
Acute And Chronic Exposure ◽  
Anthropogenic Pollutant ◽  
Incident Cases ◽  
Incidence Prevalence

Abstract Background Air pollution is one of the world’s leading mortality risk factors contributing to seven million deaths annually. COVID-19 pandemic has claimed about one million deaths in less than a year. However, it is unclear whether exposure to acute and chronic air pollution influences the COVID-19 epidemiologic curve. Methods We searched for relevant studies listed in six electronic databases between December 2019 and September 2020. We applied no language or publication status limits. Studies presented as original articles, studies that assessed risk, incidence, prevalence, or lethality of COVID-19 in relation with exposure to either short-term or long-term exposure to ambient air pollution were included. All patients regardless of age, sex and location diagnosed as having COVID-19 of any severity were taken into consideration. We synthesised results using harvest plots based on effect direction. Results Included studies were cross-sectional (n = 10), retrospective cohorts (n = 9), ecological (n = 6 of which two were time-series) and hypothesis (n = 1). Of these studies, 52 and 48% assessed the effect of short-term and long-term pollutant exposure, respectively and one evaluated both. Pollutants mostly studied were PM2.5 (64%), NO2 (50%), PM10 (43%) and O3 (29%) for acute effects and PM2.5 (85%), NO2 (39%) and O3 (23%) then PM10 (15%) for chronic effects. Most assessed COVID-19 outcomes were incidence and mortality rate. Acutely, pollutants independently associated with COVID-19 incidence and mortality were first PM2.5 then PM10, NO2 and O3 (only for incident cases). Chronically, similar relationships were found for PM2.5 and NO2. High overall risk of bias judgments (86 and 39% in short-term and long-term exposure studies, respectively) was predominantly due to a failure to adjust aggregated data for important confounders, and to a lesser extent because of a lack of comparative analysis. Conclusion The body of evidence indicates that both acute and chronic exposure to air pollution can affect COVID-19 epidemiology. The evidence is unclear for acute exposure due to a higher level of bias in existing studies as compared to moderate evidence with chronic exposure. Public health interventions that help minimize anthropogenic pollutant source and socio-economic injustice/disparities may reduce the planetary threat posed by both COVID-19 and air pollution pandemics.

scholarly journals Systemic Inflammation (C-Reactive Protein) in Older Chinese Adults Is Associated with Long-Term Exposure to Ambient Air Pollution

2021 ◽  
Vol 18 (6) ◽  
pp. 3258
Author(s):  
Mona Elbarbary ◽  
Artem Oganesyan ◽  
Trenton Honda ◽  
Geoffrey Morgan ◽  
Yuming Guo ◽  
...  
Keyword(s):  
Air Pollution ◽  
Systemic Inflammation ◽  
Ambient Air ◽  
Ambient Air Pollution ◽  
Chinese Adults ◽  
Reactive Protein ◽  
Hs Crp ◽  
Older Chinese ◽  
Older Chinese Adults

There is an established association between air pollution and cardiovascular disease (CVD), which is likely to be mediated by systemic inflammation. The present study evaluated links between long-term exposure to ambient air pollution and high-sensitivity C reactive protein (hs-CRP) in an older Chinese adult cohort (n = 7915) enrolled in the World Health Organization (WHO) study on global aging and adult health (SAGE) China Wave 1 in 2008–2010. Multilevel linear and logistic regression models were used to assess the associations of particulate matter (PM) and nitrogen dioxide (NO2) on log-transformed hs-CRP levels and odds ratios of CVD risk derived from CRP levels adjusted for confounders. A satellite-based spatial statistical model was applied to estimate the average community exposure to outdoor air pollutants (PM with an aerodynamic diameter of 10 μm or less (PM10), 2.5 μm or less (PM2.5), and 1 μm or less (PM1) and NO2) for each participant of the study. hs-CRP levels were drawn from dried blood spots of each participant. Each 10 μg/m3 increment in PM10, PM2.5, PM1, and NO2 was associated with 12.8% (95% confidence interval; (CI): 9.1, 16.6), 15.7% (95% CI: 10.9, 20.8), 10.2% (95% CI: 7.3, 13.2), and 11.8% (95% CI: 7.9, 15.8) higher serum levels of hs-CRP, respectively. Our findings suggest that air pollution may be an important factor in increasing systemic inflammation in older Chinese adults.

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