Direct growth of GaAS layers on Si substrates and the applications to devices are reported. Instead of the large lattice mismatch of 4% between these materials and the polar on nonpolar problem, single domain GaAs layers with a mirror-like surface were grown on (100)-oriented Si substrates by heat treatment at high temperatures and a subsequent two-step growth sequence at low temperatures and then at the conventional growth temperature. RHEED and cross sectional TEM observation showed that the atoms in the first layer rearranged themselves when the wafer was reheated to the conventional growth temperature and most of the dislocations due to the lattice mismatch were confined near the GaAs/Si interface.
