Heteroepitaxy on Silicon by Molecular Beam Epitaxy

Abstract

AbstractIn recent years extensive research has been conducted on growing heteroepitaxial layers of insulators, metals, and other semiconductors on silicon. This work promises to extend the use of Si (or, at least, Si substrates) far beyond present day devices into hybred semiconductor devices, optoelectronics, ballistic electron devices, and three-dimensional device structures. However, the “art” of heteroepitaxy is still poorly understood and much work remains to be done to realize most practical applications. Molecular beam epitaxy (MBE) represents an attractive technique for research and development of heteroepitaxy because of its relatively low growth temperatures, flexibility in working with different materials, and by providing a good environment for in-situ observation of the heteroepitaxial process. Using examples from recent heteroepitaxial work by molecular beam epitaxy in the areas of CaF2, NiSi2 and CoSi2, and GaAs on Si, this paper discusses how heteroepitaxial quality is affected by the relative surface free energies and strain (due to both lattice and thermal expansion coefficient mismatch). The goal is to produce better heteroepitaxial layers for device applications by an improved understanding of the process.