Photochemical Vapor Deposition

Eden, J. G.

doi:10.1016/b978-0-08-052421-4.50013-7

Cited by 24 publications

(21 citation statements)

References 123 publications

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“…The mass spectra obtained at energies lower than 21 000 cm -1 outside this scan region are dominated mostly by Cr + and fragments of the Cp group, whereas Cr(Cp) 2 + is observed at <1/15 the intensity of the metal ion. However, numerous chromium-containing molecular species, including Cr(Cp) 2 + and Cr(Cp) + begin to appear in the scan to higher energies in the region 21 000-23 530 cm -1 . The appearance of other metalcontaining fragments including CrC 2 + and CrC 3 H 3 + is also evident although the spectra are still dominated by Cr + .…”

Section: Mass Spectra a General Trends And Observationsmentioning

confidence: 99%

“…The peaks are observed at 50, 52, 53, and 54 m/z and correspond to the most abundant isotopes of chromium. When maximizing the intensity of the minor fragments, the intensities of the dominant Cr + and Cr(Cp) 2 + become saturated. Mass spectra taken at three representative wavelengths are shown in Figure 1.…”

Section: Mass Spectra a General Trends And Observationsmentioning

confidence: 99%

“…In our studies of chromium metal deposition using tris(hexafluoroacetylacetonate)chromium, Cr(hfac) 3 , as the precursor, we discovered that chromium atoms are readily formed by photolysis but that significant amounts of the undesired diatomic photofragment CrF were also produced intramolecularly. 14,15 To avoid fluorine contamination of the deposit, we investigated other chromium precursors including chromocene, bis(cyclopentadienyl)chromium, Cr(Cp) 2 .…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5] Identification and quantification of the photofragments use luminescence spectroscopy and mass spectroscopy as the primary analytical methods. [6][7][8][9][10] Our interest in the photochemistry was sparked by our observations that both desired photofragments (i.e., those having the stoichiometry of the desired deposit) and undesired species (i.e., those that lead to contamination of the desired deposit) are produced by intramolecular processes in the gas phase.…”

Section: Introductionmentioning

confidence: 99%

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Wavelength Dependence of Photooxidation vs Photofragmentation of Chromocene

2001

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Photooxidation and metal-ligand photolysis reactions of bis(cyclopentadienyl)chromium, chromocene, in the range 24 390-15 630 cm -1 are studied in the gas phase by using time-of-flight mass spectroscopic detection. Photooxidation of the intact chromocene molecule unexpectedly dominates in the range 23 530-24 000 cm -1 . The relative importance of photooxidation compared to photofragmentation is strongly wavelength dependent. A prominent species at all wavelengths is the chromium ion, but in a wavelength region corresponding to the lowest energy ligand to metal charge transfer excited electronic state absorption, the strongest peak is from the chromocene ion. The excitation spectra are reported for three selected species: chromocene ion, mono-(cyclopentadienyl)chromium ion, and the chromium ion. The spectrum obtained by monitoring the metal ion contains sharp peaks that are assigned to neutral chromium atom resonances. Sharp losses of intensities in the molecular ion spectra are observed at these wavelengths. The wavelength dependencies of the photoreactions are interpreted and explained in terms of the identity of the initially populated excited electronic state and the ionization energy of the molecule. When the initially populated excited electronic state is the ligand to metal charge transfer state, the first photon causes minimal bond weakening and the second photon excites the intact chromocene above the ionization energy, resulting in efficient ionization of the parent molecule. When the initially populated state is a lower energy ligand field excited electronic state, bond weakening occurs and absorption of a second photon results in significant photodissociation producing intense fragment peaks dominated by the metal ion peak.

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Section: Mass Spectra a General Trends And Observationsmentioning

confidence: 99%

Section: Mass Spectra a General Trends And Observationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Wavelength Dependence of Photooxidation vs Photofragmentation of Chromocene

2001

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“…The deposition at very low temperature (300 to 450 K) is allowed but having a low deposition rate and poor uniformity. (Eden, 1991;Mahajan, 1996) …”

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confidence: 99%

Systematic Strategy for Modeling and Optimization of Thermal Systems With Design Uncertainties

Jaluria¹,

Gea²,

Lin³

2010

Frontiers in Heat and Mass Transfer

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Thermal systems play significant roles in the engineering practice and our lives. To improve those thermal systems, it is necessary to model and optimize the design and the operating conditions. More importantly, the design uncertainties should be considered because the failures of the thermal systems may be very dangerous and produce large loss. This review paper focuses on a systematic strategy of modeling and optimizing of the thermal systems with the considerations of the design uncertainties. To demonstrate the proposed strategy, one of the complicated thermal systems, Chemical Vapor Deposition (CVD), is simulated, parametrically modeled, and optimized. The operating conditions, inlet velocities and susceptor temperatures, are the most significant factors in the CVD and are chosen as the design variables. Several responses -including the percentage of the working area, the mean of the deposition rate, the root mean square of the deposition, and the surface kurtosis -are chosen based on the physical needs and statistical foundations, and are utilized to represent the productivity and the quality of the thin-film deposition. One of the Response Surface Method (RSM), the Radial Basis Function (RBF), is employed to formulate the objective and constraint functions for the optimization. However, it is not until the design uncertainties are considered that the thermal system designs have high risk of the violations of the performance constraints. The Reliability-Based Design Optimization (RBDO) algorithms are used to solve the optimization problems with the design uncertainties. The most famous RBDO methods are the Reliability Index Approach (RIA) and the Performance Measure Approach (PMA). In RBDO, probabilistic constraints are established with respect to either normally or non-normally distributed random variables. The optimal solutions are found subjected to the allowable level of the failure probabilities. The Monte Carlo Simulation (MCS) results can be used to evaluate the failure probabilities. As a result, the proposed systematic strategy of parametrically modeling and optimizing with design uncertainties can be applied to either experiments or simulations of other thermal systems to quantitatively represent the performances, improve their productivity, maintain the quality control, and reduce the probability of the system failure.

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Fundamentals of Oxide Manufacturing

Pawłowski¹

2018

Industrial Chemistry of Oxides for Emerging Applications

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Photochemical Vapor Deposition

Cited by 24 publications

References 123 publications

Wavelength Dependence of Photooxidation vs Photofragmentation of Chromocene

Wavelength Dependence of Photooxidation vs Photofragmentation of Chromocene

Systematic Strategy for Modeling and Optimization of Thermal Systems With Design Uncertainties

Fundamentals of Oxide Manufacturing

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