Thin-film molecular still

Another evaporation technique is molecular beam epitaxy (MBE). MBE produces extremely pure and very thin films with abrupt composition changes and is being considered for extremely exacting electronic and optoelectronic applications. PI However, the deposition rate is very slow and the process is still considered experimental. 

Figure 13.30. Molecular distillation and related kinds of equipment, (a) Principle of the operation of the falling film still (Chemical Engineers Handbook, McGraw-Hill, New York, 1973). (b) Thin-layer evaporator with rigid wiper blades (Luwa Co., Switzerland), (c) The Liprotherm rotating thin film evaporator, for performance intermediate to those of film evaporators and molecular stills (Sibtec Co., Stockholm), (d) Centrifugal molecular still [Hickman, Ind. Eng. Chem. 39, 686 (1947)].

Molecular beam methods are now widely used for the preparation of common semiconductors such as GaP and their intergrowth with other compounds. Thin films of iron phosphides of 0.5 to 25 J,m thickness can be electrodeposited from sulfate solutions. Depending on the deposition conditions (time, pH, temperature), the phosphides FeP, Fe2P, and/or FesP occur. The preparation of higher polyphosphides, for example, KP15, as thin films demonstrates the range of still yet unexplored preparative methods. This is also valid for the electrolysis of phosphates. The latter techniques is mostly suited for metal-rich phosphides. ... 

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