Silicon molecular beam epitaxy

Abstract

The silicon molecular beam epitaxy (MBE) technique has only been used in silicon device applications in the last 5 years. The potential of silicon epitaxial growth by vacuum evaporation of silicon was recognized much earlier, and experiments can be traced back even to the late 1950s. Although the study of silicon MBE techniques started at almost the same time as the chemical vapor deposition technique, it was not until 1977 that the first high quality silicon epitaxial samples were grown. Since then, it has been amply demonstrated that the silicon MBE technique is capable of producing epitaxial films suitable for silicon device applications. Because of the low growth temperature, flexible and precise doping capability and precise thickness control of silicon MBE, unique silicon devices have been produced. Considering the recent rapid progress in the technique, it is expected that in the near future silicon MBE will be applied to a much wider range of silicon devices including silicon integrated circuits. This reviewer takes a closer look at the basics of the silicon MBE system design, including such fundamental issues as the essential diagnostic methods for characterizing and monitoring an epitaxial film during its growth, the electrical and crystalline properties, and device applications based on both developments in this laboratory and results obtained by numerous other workers in silicon MBE. This review also includes a discussion of germanium MBE techniques needed to grow a high quality germanium epitaxial film. It has been found that germanium MBE requires as careful a process as that employed in silicon MBE.