GaAs on Si: progress and promise

Summary form only given, as follows. In spite of the large mismatch in lattice dimensions and thermal expansion properties, remarkable progress has been made in epitaxially depositing GaAs on Si substrates. The epitaxial layer quality, although clearly inferior to that of GaAs deposited on GaAs, is adequate for laboratory-scale fabrication of a variety of electronic and optoelectronic devices that exhibit reasonable performances. Two broad areas for applications of GaAs on Si are being considered. In one the Si serves to replace conventional GaAs substrate wafers with larger, stronger and less expensive Si substrates. The other, a longer range and more difficult application, involves fabrication of active devices both in the GaAs epitaxial layer and in the underlying Si substrate. An assessment of these applications with reference to the improvements in material quality that each requires is given.