Vacuum deposition, definition

It has been observed by some experimenters, but not by the others, that the experimental lattice constant a in crystals of ordinary size was different from that, a + A a, found in extremely small crystals. A recent example72 refers to vacuum-deposited copper grains whose diameter D (they were, of course, not spherical) varied from 24 to 240 angstroms. The lattice constants calculated from the (111) reflexions increased from 3.577 to 3.6143 angstroms when the grain volume decreased, but the particle size had no definite effect on the reflexions from the 220 plane. 

In order to find the domain of LCVD, it is necessary to compare various vacuum deposition processes chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma chemical vapor deposition (PCVD), plasma-assisted CVD (PACVD), plasma-enhanced CVD (PECVD), and plasma polymerization (PP). All of these terms refer to methods or processes that yield the deposition of materials in a thin-film form in vacuum. There is no clear definition for these terms that can be used to separate processes that are represented by these terminologies. All involve the starting material in vapor phase and the product in the solid state. 

In simple equipment, only relatively wide transmission bands are selected by means of colored glass or interference filters. A working beam of narrow bandwidth is obtained by combining this with a mercury source. Interference filters give spectral bandwidths in the 3-10-nm range [42], [68]. These operate on the principle of multiple reflections between layers of dielectric material that have been produced in a definite sequence by vacuum deposition. The wave character of light leads to interference of the reflected beams at... 

A nonproportional sampler is suitable for near-constant flow conditions. The sample is simply drawn from the waste stream at a constant flow rate. Sampling lines should be as short as possible and free from sharp bends, which can lead to particle deposition. Proportional samplers are designed to collect either definite volumes at irregular time intervals or variable volumes at equal time intervals. Both types depend on flow rate. Examples of some of these are the vacuum and chain-driven wastewater samplers. Other types, which have cups mounted on motor driven wheels, vacuum suction samplers, and peristaltic pump samplers, are also available (26,27). 

Fig. 5.6. Reactive sputter process for depositing the compound film AB. (a) Balance of reactive gas flow Qtot, which is partially gettered at the target (Qt) and at the substrate (Qc) and partially pumped by the vacuum pump (Qp). The fraction of the target surface At that is covered by the compound AB is 6>t. The fraction of the collecting area Ac covered is Gc. j is the sputter current density, (b) Definition of particle fluxes that alter the target and collecting area coverage fractions 6>t and 6>c (see text), (modified from [70])...

In order to verify this claim and to definitively establish the role of absorbed water in the polyimide, the following experiment was performed. Ti/ thick Cu peel strips were deposited on polyimide coated substrates as before, but the vacuum chamber was purged with dry Nj or forming gas after completing the deposition and the samples were annealed at 350°C, in situ. 

The positron source, 120 kBq of Na, was deposited onto a Kapton foil covered with identical foil and sealed. The foil 8 pm thick absorbed 10% of positrons in polyimides Ps does not form and annihilation in the source envelope gave one component only = 374 ps, which must be taken into account. The source was sandwiched between two samples of the material studied and placed into a container in a vacuum chamber. The source-sample sandwich was viewed by two Pilot U scintillators coupled to XP2020Q photomultipliers. The resolution of our spectrometer with a stop window broadened to 80% (in order to register the greatest number of three-quantum decays) was 300 ps FWHM. The finite resolution had no influence on the results of our experiment as FWHM was still comparable to the channel definition At = 260 ps.The positron lifetime spectra were stored in 8000 channels of the Tennelec Multiport E analyser. 

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