Deposition setup

The deposition setup as shown in Figure 4a is the central part of the most commonly used planar diode deposition system. The power to the reactor system is delivered by means of a power supply connected to the reactor via appropriate dc or RF circuitry (matchboxes). Power supplies can consist of generator and amplifier combined in one apparatus, with a fixed RF frequency. More flexible is to have an RF generator coupled to a broadband amplifier [119, 120]. 

During deposition, there will be an optimum substrate temperature (or possibly a series of temperatures as the deposition progresses) for the formation of high quality crystals, exclusion of water, and adjustment of the crystal phase. These parameters will not be exactly the same for each deposition setup, but some t q)ical starting points are presented in Appendix B and in the literature (see, for example, [40] and [65]). Some experimentation is required to determine the optimum thickness, rate, and substrate temperature for a given deposition and material system. 

FIGURE 3.8 Schematics of previous (top) and recent (bottom) arrangement of the cluster deposition setup with laser ablation source and quadrupole mass spectrometer at the Argonne National Laboratory. Reprinted with permission from Refs. [Ill, 112]. Springer Science+Business Media. 

FIGURE 3.9 Schematic of the cluster deposition setup with ACIS at the Universitat Rostock. Reprinted with permission from Ref. [119]. Elsevier B.V. 

The low-energy cluster beam deposition setup at the Universitat Karlsruhe consists of three differential pumping stages as shown in Figure 3.20. Their source produces ions through electron impact induced ionization/desorption of powder in a... 

FIGURE 3.11 Schematic of cluster deposition setup at the Technische Universitat Munchen. Reprinted with permission from Ref. [48]. American Institute of Physics. 

Fig. 20.29 Diagrammatical representation of the deposition setup used for suspension-free spray deposition (Reprinted with permission from Sahner et al. 2009. Copyright 2009 Elsevier)...

A schematic sketch of the sample deposition setup is shown in Fig. 3.12. After mass selection by means of the QMS (see Sect. 3.1.2) the clusters leave the QMS trough an exit lens attached to the QMS body. In an UHV chamber cross (2 x 10 mbar without deposition, 5 x 10 mbar during deposition) the cluster beam is then guided through aAfo shield (5) with an aperture of 9 mm (fixed on a grounded Cu feedthrough... 

Figure 7.4. Electrospray sample deposition setup employed for preparation of MALDI sample slides. (Reproduced with permission ftom Axelsson, J. Hoberg, A.-M. Waterson, C. Myatt, P. Chield, G. Varney, J. Haddleton, D. Derrick, J. Improved reproducibility and increased signal intensity in MALDI as a result of electrospray sample preparation. Rapid Commun. Mass Spectrom. 1997, 11, 209-213.)...

Fig. 7. Fiber formation by MCVD, where V represents the O2—H2 flame, showing (a), tube setup (b), deposition and (c), coUapse.

An important method for producing semiconductor layers is the so-called molecular beam epitaxy (MBE) (see [3,12-14] and [15-19]). Here, atoms of the same or of a different material are deposited from the vapor source onto a faceted crystal surface. The system is always far from thermal equilibrium because the deposition rate is very high. Note that in this case, in principle, every little detail of the experimental setup may influence the results. 

Figure 5.21. Experimental setup (inset) showing the location of the working (WE), counter (CE) and reference (RE) electrodes and of the heating element (HE) thermal desorption spectra after gaseous oxygen dosing at 673 K and an 02 pressure of 4x1 O 6 Torr on Pt deposited on YSZ for various exposure times. Oxygen exposure is expressed in kilo-langmuirs (1 kL=l0 3 Torrs). Desorption was performed with linear heating rate, ()=1 K/s.4 S Reprinted with permission from Academic Press.

The experimental setup used for the first bipolar or wireless NEMCA study is shown in Figure 12.6.8 An YSZ disc with two terminal Au electrodes and one Pt catalyst film deposited on one side and a reference Au electrode on the other side is placed in a single-chamber reactor. Ethylene oxidation on the Pt catalyst film was chosen as a model reaction.8... 

For this purpose we studied a temperature-programmed interaction of CH with a-oxygen. Experiments were carried out in a static setup with FeZSM-5 zeolite catalyst containing 0.80 wt % Fe203. The setup was equipped with an on-line mass-spectrometer and a microreactor which can be easily isolated from the rest part of the reaction volume. The sample pretreatment procedure was as follows. After heating in dioxygen at 823 K FeZSM-5 cooled down to 523 K. At this temperature, N2O decomposition was performed at 108 Pa to provide the a-oxygen deposition on the surface. After evacuation, the reactor was cooled down to the room temperature, and CH4 was fed into the reaction volume at 108 Pa. 

In the ASTER system (see Section 1.2.4), experiments were performed in order to test this scaling law. To this end, a newly designed RF electrode assembly was retrofitted to a deposition chamber. With this electrode setup, it was possible to change the electrode distance from the outside, without breaking the vacuum. A large data set was taken, consisting of 420 data points [162] at three values of the pressure (0.1 < p < 0.45 mbar), five of the RF power (5 < P < 25 W), seven of the electrode distance (12 < L < 30 mm), and four of the RF frequency (13.56 < o)/2n < 50 MHz). 

With the setup described, a series of depositions was carried out [531, 548], in which the substrate temperature was varied between 125 and 650°C. the pressure between 0.007 and 0.052 mbar. the gas flow rate between 15 and 120 seem, and the dilution of the silane gas with hydrogen ([SiHaj/flSiHa] + [Hi])) between 0.1 and 1. Under these conditions the deposition rate varied between 1 and 2.5 nm/s [531 ]. Molenbroek et al. [530] reported a variation of the deposition rate between 1 and 9 nm/s for similar process conditions, at a filament temperature of 2000°C. 

QMS) and an ellipsometer complete the setup. The typical pressure is in the range of 0.15-0.5 mbar. The deposition chamber has a volume of 180 1. During processing it is pumped by a stack of two Roots blowers and one forepump (total pumping capacity is about 1500 m /h) otherwise it is pumped by a turbo pump (4501/s), with which a base pressure of 10 mbar is reached. 

The design and implementation of a portable fiber-optic cholinesterase biosensor for the detection and determination of pesticides carbaryl and dichlorvos was presented by Andreou81. The sensing bioactive material was a three-layer sandwich. The enzyme cholinesterase was immobilized on the outer layer, consisting of hydrophilic modified polyvinylidenefluoride membrane. The membrane was in contact with an intermediate sol-gel layer that incorporated bromocresol purple, deposited on an inner disk. The sensor operated in a static mode at room temperature and the rate of the inhibited reaction served as an analytical signal. This method was successfully applied to the direct analysis of natural water samples (detection and determination of these pesticides), without sample pretreatment, and since the biosensor setup is fully portable (in a small case), it is suitable for in-field use. 

Surface Acoustic Waves (SA Ws). The basic idea of this technique is to use the dependence of the frequency and propagation of surface acoustic waves on mass loading in a film. The porous film has to be deposited on a piezoelectric substrate (quartz), which is then placed into a physisorption setup to condense nitrogen at 77 K. Adsorption and condensation of N2 result in a shift of the oscillation frequency, and thus measurements of the oscillation frequency as a function of N2 partial pressure provide an adsorption-desorption isotherm.30 Although the technique has proven to provide a concise characterization of porous films,29,30 the requirement for the deposition directly onto the SAW piezoelectric substrate represents a certain restriction. 

The experimental setup was virtually identical to that depicted in Fig. 3.11 with two broadband superluminescent diodes (2 mW) operating at 1,310 and 1,550 nm, respectively, and an optical spectrum analyzer for transmitted spectrum monitoring with a resolution of 0.05 nm. A holder similar to that used for the deposition was used to host the coated LPG allowing also the conveying of pure distilled water or polluted water as the case. The temperature was held constant at 20°C. 

Liu et aU622] used a laser Doppler velocity and size (LDVS) measurement technique to determine the local size, velocity, and number flow density of droplets in the spray cone during spray deposition of a liquid steel. The experimental setup is schematically depicted in Fig. 6.7.1615] The measured results showed that smaller... 

In all three described setups, deposition on the inserts was 50% or less of the amount usually anticipated on an equal sized area without cell culture inserts. This difference may be explained by the changed distance between orifice plate and impaction surface in the cell culture insert. The collection efficacy of an impactor/impinger decreases with an increase in the ratio of the orifice plate to impaction plate distance over jet width. Observations indicate that although the inserts are not at an optimal distance from the orifice plate and are not exactly at the same position compared to the original collection stage, the cell culture inserts do function as an impaction surface for particles in a relevant size range. 

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