Growth in High Vacuum

Technological developments in high vacuum evaporation techniques have been responsible for the rapid growth of the domestic citrus industry. These techniques were developed and refined, for the most part, during World War II and they made possible the manufacture and production of many perishable foods and medicines. Most notable for the domestic citrus industry was the development of frozen concentrated citrus juices which was made possible by the development of these high vacuum evaporators... 

Critical size / density Needle growth by agglomeration Figure 8.3 Sketch of the growth model for nanofibers via sublimation in high vacuum. 

The subject of metal surfaces should not be left without a mention of the very important role that clean tungsten in high vacuum has played as a model for understanding surface phenomena. However many interesting surfaces are so complicated (dirty) and thus so far from this model, that the model is of little use for this type of surface. But it has contributed to the growth of the "dean surface school who appear to believe that all one can hope to understand is a clean surface with at most a monolayer of a foreign species. 

Condensation, nucleation and growth phenomena have been investigated both theoretically and experimentally for films made under conditions typical for physical vapour deposition in high vacuum. A number of papers concerning this topic are listed in ref. [42]. 

Molecular beam epitaxy (MBE) is a radically different growth process which utilizes a very high vacuum growth chamber and sources which are evaporated from controlled ovens (15,16). This technique is well suited to growing thin multilayer stmctures as a result of very low growth rates and the abihty to abmpdy switch source materials in the reactor chamber. The former has impeded the use of MBE for the growth of high volume LEDs. 

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