The heteroepitaxial overgrowth of silicon by nearly lattice-matched compound semiconductors is reviewed in the context of the separation of the chemical problems associated with the initial sealing of the silicon surface by a contiguous epitaxial compound film from the problems associated with the generation of strain during heteroepitaxial growth. Of the mixed compound systems available dilute solid solutions of composition Al x Ga 1Ϫx N y P 1Ϫy and ZnS y Se 1Ϫy as well as ZnSi x Ge 1Ϫx P are suitable candidates for the exactly lattice-matched epitaxial overgrowth of silicon. Real-time process monitoring by nonintrusive methods is important for gaining an understanding of the epitaxial overgrowth mechanism and for controlling the film properties. A new method, p-polarized reflectance spectroscopy is introduced that provides detailed information about the growth rate per cycle, the bulk optical properties of the film and its topography. Submonolayer resolution is accomplished for thousands of Å of film growth by pulsed chemical beam epitaxy. While the cubic materials considered here generally afford easier control of the electrical and optical properties, the noncubic materials have advantages in the sealing of the silicon surface because of their anisotropic growth and the formation of metastable solid solutions that may permit the graded growth of compound films under exactly lattice-matched conditions. Therefore, no clear-cut preference in the materials selection for nearly lattice-matched overgrowth of silicon by compound semiconductors can be identified at this time
