MOCVD HTSC Precursor Delivery Monitored By UV Spectroscopy

1995 ◽  
Vol 415 ◽  
Author(s):  
Brian J. Rappoli ◽  
William J. DeSisto
Keyword(s):  
Gas Phase ◽  
Uv Spectroscopy ◽  
Diagnostic Technique ◽  
Chemical Vapor ◽  
Test System ◽  
Small Scale ◽  
Mocvd Reactor ◽  
Phase Concentration ◽  
Scale Test

ABSTRACTUV spectroscopy has been used as an in situ diagnostic to measure the gas phase concentration of 2,2,6,6-tetramethyl-3,5-heptanedionate (thd) complexes of Ba, Cu and Y in metalorganic chemical vapor deposition (MOCVD) bubbler effluent. These precursors for MOCVD synthesis of YBa2Cu37−δ (YBCO) show marked instability in gas phase concentration as a function of time during bubbler purge. The UV diagnostic technique has been applied to both a small scale test system and a commercial scale MOCVD reactor.

scholarly journals A Study of CVD of Gallium Nitride Films by In Situ Gas-Phase UV Spectroscopy

1995 ◽  
Vol 05 (C5) ◽  
pp. C5-183-C5-190 ◽  
Author(s):  
S. E. Alexandrov ◽  
A. Y. Kovalgin ◽  
D. M. Krasovitskiy
Keyword(s):  
Gallium Nitride ◽  
Gas Phase ◽  
Uv Spectroscopy

In-situ kinetics study of gas phase formation in the system Ga/In-AsCl 3 -HCl-H 2 by UV spectroscopy

2001 ◽  
Author(s):  
Valery A. Voronin ◽  
Sergey K. Guba ◽  
Marina A. Litvin ◽  
A. Y. Kulikov
Keyword(s):  
Gas Phase ◽  
Phase Formation ◽  
Uv Spectroscopy ◽  
Kinetics Study

The Effect of Polysilicon Deposition and Doping Processes on Double-Poly Capacitors - Electrical and AFM Evaluation

1993 ◽  
Vol 324 ◽  
Author(s):  
W. M. Paulson ◽  
L. H. Breaux ◽  
R. I. Hegde ◽  
P. J. Tobin
Keyword(s):  
Gas Phase ◽  
Diagnostic Technique ◽  
Surface Structures ◽  
Semiconductor Processing ◽  
Amorphous Films ◽  
Leakage Currents ◽  
Low Leakage ◽  
Oxide Removal ◽  
Non Destructive

AbstractWe have characterized the surface topography of silicon films from different deposition and doping process sequences using AFM and optical reflectivity. The resulting surface structures after deposition, doping, oxide growth, and oxide removal correlate with the electrical leakage currents and breakdown voltages of double polysilicon capacitors. As-deposited amorphous films had smoother surfaces than those deposited in the crystalline state. Gas-phase diffusion doping increases the surface roughness. Only the amorphous in situ doped films retained a smooth surface following oxidation, yielding low leakage capacitors with breakdown fields above 8 MV/cm. Surprisingly, implanted amorphous films exhibited the roughest interfaces, resulting in lower breakdown fields. This study has shown that AFM provides an effective, quick, non-destructive diagnostic technique for semiconductor processing.

New approaches to characterizing and understanding biofouling of spiral wound membrane systems

2012 ◽  
Vol 66 (1) ◽  
pp. 88-94 ◽  
Author(s):  
Mark C. M. van Loosdrecht ◽  
Ludmilla Bereschenko ◽  
Andrea Radu ◽  
Joop C. Kruithof ◽  
Cristian Picioreanu ◽  
...  
Keyword(s):  
Small Scale ◽  
Clear Understanding ◽  
Membrane Systems ◽  
Basic Principles ◽  
Scientific Approach ◽  
Scale Test ◽  
Negative Impacts ◽  
Integrated Study ◽  
Spiral Wound

Historically, biofouling research on spiral wound membrane systems is typically problem solving oriented. Membrane modules are studied as black box systems, investigated by autopsies. Biofouling is not a simple process. Many factors influence each other in a non-linear fashion. These features make biofouling a subject which is not easy to study using a fundamental scientific approach. Nevertheless to solve or minimize the negative impacts of biofouling, a clear understanding of the interacting basic principles is needed. Recent research into microbiological characterizing of biofouling, small scale test units, application of in situ visualization methods, and model approaches allow such an integrated study of biofouling.

MOCVD Precursor Delivery Monitored and Controlled Using UV Spectroscopy

1997 ◽  
Vol 474 ◽  
Author(s):  
Brian J. Rappoli ◽  
William J. DeSisto ◽  
Tobin J. Marks ◽  
John A. Belot
Keyword(s):  
Thin Films ◽  
Gas Phase ◽  
Uv Spectroscopy ◽  
Mixed Metal Oxide ◽  
Feedback Control System ◽  
Metal Oxide Films ◽  
Mocvd Growth ◽  
Mocvd Precursor ◽  
Htsc Thin Films

ABSTRACTThe glyme adducts of bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionate)barium, Ba(hfac)2•glyme, are frequently employed as precursors in the MOCVD fabrication of HTSC thin films. The physical properties of these precursors can be modified by changing the glyme ligand in the barium complex. In this study, gas phase concentrations of two barium complexes as a function of purge time and bubbler temperature have been examined by in-situ UV spectroscopy. Also presented are the details of a UV spectrophotometric-based feedback control system designed to maintain constant gas phase concentration of 2,2,6,6-tetramethyl-3,5-heptadionate (thd) precursors, Cu(thd)2 and Y(thd)3, during MOCVD growth of mixed metal oxide films.

Chemical Vapor Functionalization of ZnO Nanocrystals

2010 ◽  
Vol 1260 ◽  
Author(s):  
Moazzam Ali ◽  
Marty D. Donakowski ◽  
Markus Winterer
Keyword(s):  
Gas Phase ◽  
Diffuse Reflectance ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Zno Nanocrystals ◽  
In Series ◽  
Lower Temperature ◽  
Diffuse Reflectance Infrared

AbstractChemical Vapor Functionalization (CVF) is a method in which nanocrystals undergo in situ functionalization in the gas phase. In CVF, two reactors are used in series. The first reactor consists of a hot quartz tube (1073 K) where ZnO nanocrystals are synthesized in the gas phase from diethylzinc and oxygen. The second reactor, connected at the exit of the first one and kept at lower temperature (673 K), is used as functionalization chamber. At the connecting point of the two reactors, vapors of organic functionalizing agents are injected which react with the surface of ZnO nanocrystals. ZnO nanocrystals have been functionalized by 1-hexanol, n-hexanoic acid, n-hexanal and 1-hexylamine. Functionalized ZnO nanocrystals have been characterized by Dynamic Light Scattering, X-ray Diffraction and Diffuse Reflectance Infrared Fourier Transform Spectroscopy.

FTIR In Situ Studies of the Gas Phase Reactions in Chemical Vapor Deposition of SiC

1995 ◽  
Vol 142 (7) ◽  
pp. 2357-2362 ◽  
Author(s):  
S. Jonas ◽  
W. S. Ptak ◽  
W. Sadowski ◽  
E. Walasek ◽  
C. Paluszkiewicz
Keyword(s):  
Chemical Vapor Deposition ◽  
Gas Phase ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Gas Phase Reactions ◽  
In Situ Studies

Effect of pressure on the gas-phase chemistry when using monomethylsilane and dimethylsilane in hot-wire chemical vapor deposition

2015 ◽  
Vol 93 (1) ◽  
pp. 82-90 ◽  
Author(s):  
Rim Toukabri ◽  
Yujun Shi
Keyword(s):  
Free Radical ◽  
Gas Phase ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Phase Reaction ◽  
Hot Wire ◽  
Gas Phase Reaction ◽  
Gas Phase Chemistry ◽  
Phase Chemistry

The effect of source gas pressure on the gas-phase reaction chemistry of dimethylsilane (DMS) and monomethylsilane (MMS) in the hot-wire chemical vapor deposition process has been studied by examining the secondary gas-phase reaction products in a reactor using a soft laser ionization source coupled with mass spectrometry. For DMS, the increase in sample pressure has resulted in the formation of small hydrocarbons, including ethene, acetylene, propene, and propyne. This leads to a switch from silylene dominant chemistry to a free radical dominant one with the pressure increase at low filament temperatures of 1200 and 1300 °C. At the lower pressure of 0.12 Torr, the formation of 1,1,2,2-tetramethyldisilane by dimethylsilylene insertion reaction into the Si–H bond in DMS is favored over trimethylsilane produced from a free radical recombination reaction for a short reaction time. However, when the pressure is increased by 10 times, the gas-phase chemistry becomes dominated by the formation of trimethylsilane. We have demonstrated that trapping of the corresponding active intermediates by the small hydrocarbons produced in situ is responsible for the observed switch. In the study with MMS, the gas-phase chemistry is dominated by the formation of 1,2-dimethyldisilane and 1,3-disilacyclobutane at both pressures of 0.48 and 1.2 Torr. Unlike DMS, the gas-phase reaction chemistry with MMS does not involve free radicals, which are the precursors to produce small hydrocarbons. The absence of small hydrocarbons formed in situ with MMS explains the preservation in chemistry upon the increase in pressure when MMS is used as a source gas.

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