Evaporation Sources

The thennal evaporation source was the earliest used to produce metal clusters in the gas phase [H, 12 and 13], mostly for clusters of the alkalis and other low melting point materials. In this technique, a bulk sample is simply... 

Kunkei, B. A., 1983, A Comparison of Evaporative Source Strength Models for Toxic Chemical Spills , AFGL-TR83-0307, ADA139431. 

Film deposition on a single crystal substrate can, in principle, lead to the formation of an epitaxed single crystal film. However, relatively limited use has been made of well-epitaxed single crystal films for catalysts for two reasons In many instances the single crystal substrate is only available with very limited dimensions so that the film catalyst is also correspondingly restricted in its area second, in most cases it is either inconvenient or impossible to design the single crystal substrate and the evaporation source... 

Fig. 4. Sliding cathode phototube (41) showing evaporation sources (1, 2) for depositing the alloy film on the photocathode (3), shielded partly as required by the glass screen (4). A quartz window (5) faces the cathode and connection is made to a gold film anode evaporated from (6).

The deposition geometry, i.e., the relative position of the substrate and sources, is of paramount importance when fabricating OLEDs (see Figure 7.4). For a substrate on a plane at right angles to a point evaporation source, the deposited film thickness d can be expressed by the following relationship ... 

Shadowing techniques. The principles of the present method is shown schematically In Figure 1. The evaporation source is a... 

This response is recorded, and then improved control parameters for a new test are estimated. This procedure is continued until a satisfactory result is achieved. At the end the controller is optimized so that its parameters exactly match the characteristics of the evaporator source. 

It is a long and frustrating process to adjust a controller to an evaporation source, requiring several minutes for stabilization and hours to obtain satisfactory results. Often the parameters selected for a certain rate are not suitable for an altered rate. Thus, a controller should ideally adjust itself, as the new controllers in INFICON coating measuring units do. At the beginning of installation and connection the user has the unit measure the characteristics of the evaporation source. Either a PID controller is used as the basis for slow sources or another type of controller for fast sources without significant dead time. 

However, the IC/5 offers all comfort functions available today measurement with up to eight sensors with AutoZero and AutoTune as virell as capability of simultaneous control of two evaporator sources. Moreover, it offers 24 material programs, with which 250 coatings in 50 processes can be programmed. To simplify operation and avoid errors, the unit also has a diskette drive. All types of crystal holders can be connected here. The thickness resolution is around 1 A, the rate resolution for rates between 0 and 99.9 A/s around 0.1 A/s and for rates between 100 and 999 A/s around 1 A/s. A particularly attractive option offered by the IC/5 is a microbalance... 

The thermal instability of Baj.xKxBiOj compounds makes it desirable to utilize low temperature deposition techniques. Use of a three cell evaporation source coupled with oxygen, ionized by an electron cyclotron resonance source and accelerated toward the... 

Table 8.1.4 Characteristics of Ultrafine Particles Formed by Evaporating Source Metals in an Atmosphere of N2 or NH3 at About I Torr...

The film thickness uniformity and film composition depend, in part, on the molecular or atomic flux variation across a substrate. This flux variation is a function of the directionality of the evaporation source (i.e., the molecular-beam distribution) and the orientation of the substrate relative to the source (7). In this section, the fundamental equations that describe the distribution of the incident flux will be introduced, along with the solution of these equations for the evaporation of group II-VI compound-semiconductor materials. 

Electron Beam Evaporation. Most electron beam evaporation sources have a probability distribution that can be approximated by the cosine law ... 

Figure 6. Molecular-beam distribution for electron beam evaporation source obeying the cosine law.

Evaporative sources of PCNs to air over the lakes were dominant, although minor contributions of combustion sources were indicated by the presence of combustion-related congeners CN44,29, and 54 [63]. 

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