Since a molecular-beam apparatus was first successfully used by Cho and Arthur in the late 1960s to crystallize and investigate GaAs epilayers, high vacuum epitaxial growth techniques using particle beams have developed rapidly. This development accelerated when different semiconductor devices with quantum- well structures were invented in the 1970s. The important implementation of these structures in devices like quantum-well lasers, high electron mobility tran- sistors or superlattice avalanche photodiodes gave added impetus to research work and to increasing production aims. Coincident with this development, orig- inal research papers and reviews devoted to problems concerning these growth techniques have also rapidly grown in number, and in addition they have become very disversified. At present several hundred original papers on this subject ap- pear in the literature each year. However, in contrast to this there is a lack of comprehensive monographs comprising the whole variety of problems related to epitaxial growth of semiconductor films from atomic and molecular beams. This book, which presents a review of the state of the art of molecular beam epitaxy (MBE), as applied to the growth of semiconductor films and multilayer structures, may serve the reader as a convenient general guide to the topics related to this crystallization technique.